The d- and f-Block Elements: Class 12 Chemistry Chapter 4 Hinglish mein

Chemistry Part 1 · Hinglish notes, simulations aur practice · Official NCERT chapter PDF ↗

Published 12 Oct 2026 · Updated 12 Oct 2026

130 min
43 practice questions
46 MCQs

Is chapter mein aap kya seekhenge

Periodic table mein d- aur f-blocks dhoondho aur tay karo ki koi element transition element gina jaata hai ya nahi
d- aur f-block atoms aur ions ki ground-state configurations likho, aur chromium aur copper jaise exceptions samjhao
3d series mein atomisation enthalpy, size, ionisation enthalpy, oxidation states aur electrode potentials ke trends samjhao
Magnetic moments, colour, complex formation, catalysis, interstitial compounds aur alloys ko partly filled d orbitals se jodo
Potassium dichromate aur potassium permanganate ki preparation, structure aur oxidising reactions batao, aur unki ionic equations balance karo
Lanthanoids aur actinoids ko configuration, size, oxidation states aur reactivity mein compare karo
d- aur f-block elements aur unke compounds ke important uses batao

NCERT Chemistry Class 12, Chapter 4, pp. 89–117 par based original companion text. Yeh NCERT se juda nahi hai aur NCERT ne ise endorse nahi kiya hai.

Delhi ke Mehrauli mein ek iron pillar lagbhag solah sadiyon se khule mein khada hai aur us par mushkil se jang laga hai. Periodic table ke beech wale hisse mein iron ke saath copper, silver, gold, titanium aur platinum bhi hain: yahi metals tools, coins, wires, bridges aur jewellery mein lagte hain. Yeh chapter usi beech wale region, yaani d-block, ke baare mein hai, aur un do rows ke baare mein bhi jo main table ke neeche alag se chhapi hoti hain, yaani f-block.

d-block atoms mein jo electrons sabse aakhir mein aate hain, woh outermost shell ke neeche wale shell ke d subshell mein jaate hain, yaani $(n - 1) d$ subshell mein. f-block atoms mein woh aur bhi andar, $4 f$ ya $5 f$ subshell mein jaate hain. Chemists d-block elements ko transition elements (संक्रमण तत्व) aur f-block elements ko inner transition elements kehte hain. 4f elements lanthanoids hain aur 5f elements actinoids.

Definition

Transition element

Aisa element jiske atom mein, ya uske kisi common ion mein, d subshell adhoora bhara ho (IUPAC definition).

ExampleIron: $F e$ $3 d^{6} 4 s^{2}$ hai, aur $F e^{3 +}$ $3 d^{5}$ hai.

Yeh naam electrons ki hamari samajh se bhi purana hai. Pehle ke chemists in metals ko table ke left wale bahut reactive metals aur right wale elements ke beech ek bridge maante the. Position aur properties, dono mein yeh ek side se doosri side tak ek 'transition' dikhate the. Aaj yeh label electrons se tay hota hai, jaisa upar ki definition mein hai. Is test se teen jaane-pehchaane metals bahar ho jaate hain, zinc, cadmium aur mercury, jiski wajah Section 4.2 mein saaf hogi; phir bhi woh is chapter mein rehte hain, kyunki woh d-series ko poora karte hain.

f-block India ke liye bahut practical tareeke se important hai. Kerala aur Odisha ke coasts ki kaali ret mein monazite hota hai, ek mineral jismein cerium, lanthanum, neodymium aur actinoid thorium bharpoor hain. Neodymium motors aur earphones ke strong magnets mein jaata hai, aur thorium India ke nuclear power programme ke aakhri stage ka planned fuel hai.

Detail mein jaane se pehle dekh lo chapter kaise chalta hai: pehle d-block (Sections 4.1 se 4.4), jismein zyada dhyaan pehli row, scandium se zinc, par hai; phir f-block (Sections 4.5 aur 4.6); aur aakhir mein dono ke uses (Section 4.7).

4.1 Periodic Table mein Position

Periodic table dekho: d-block beech mein das columns ki chaudi patti hai, groups 3 se 12, jiske left mein s-block aur right mein p-block hai. Chauthe period se aage har period mein das d-block elements ki ek row hoti hai, kyunki ek d subshell mein das electrons aate hain.

3/4Lanthanoids (4f) aur actinoids (5f) ko nikaal kar neeche chhapa jaata hai, taaki table 32 columns chauda na ho.

Fig. 4.1Periodic table ke chaar blocks. f-block ki rows asal mein periods 6 aur 7 ke andar hoti hain.NCERT p. 89

Periodic table ki ek outline, chhote squares ke grid ki tarah. Pehle step mein sirf left ke do columns (s-block) aur right ke chhe columns (p-block) shaded hain. Doosre step mein periods 4 se 7 ke beech wale das columns d-block ke roop mein shaded hote hain; rows par 3d, 4d, 5d aur 6d likha hai aur 3d row ke pehle aur aakhri squares par Sc aur Zn mark hain. Teesre step mein table ke neeche chaudah squares ki do alag rows shaded hoti hain, jin par 4f lanthanoids aur 5f actinoids likha hai; star marks unhe periods 6 aur 7 ke group 3 mein unki jagah se jodte hain. Aakhri step mein group 12 column ke chaaron taraf dashed box hai aur ek note kehta hai ki iska d shell hamesha bhara rehta hai.

3d series (period 4): scandium ( $Z = 21$ ) se zinc ( $Z = 30$ ) tak.
4d series (period 5): yttrium ( $Z = 39$ ) se cadmium ( $Z = 48$ ) tak.
5d series (period 6): lanthanum ( $Z = 57$ ), phir hafnium ( $Z = 72$ ) se mercury ( $Z = 80$ ) tak.
6d series (period 7): actinium ( $Z = 89$ ), phir rutherfordium ( $Z = 104$ ) se copernicium ( $Z = 112$ ) tak.

5d aur 6d series ke beech ke gaps mein hi f-block fit hota hai. Lanthanum ke baad chaudah electrons 4f subshell bharte hain (cerium se lutetium), phir hafnium se 5d series dobara shuru hoti hai. Actinium ke baad 5f subshell thorium se lawrencium tak bharta hai. In 28 elements ko main table ke andar chhapne se woh bahut chauda ho jaata, isliye unhe neeche apni alag do rows milti hain.

4.2 d-Block Elements ki Electronic Configurations

Ek d-series mein aage badhne par har step par nuclear charge ek se badhta hai, aur extra electron aam taur par $(n - 1) d$ subshell mein jaata hai, jabki bahar wale $n s$ subshell mein ek ya do electrons rehte hain. Isliye outer electrons ka general pattern hai

General outer configuration

(n - 1) d^{1 – 10} n s^{1 – 2}

(4.1)

3d row ke do atoms is pattern ko todte hain (Fig. 4.2). 3d se pehle 4s bharne ke hisaab se chromium ke liye $3 d^{4} 4 s^{2}$ aur copper ke liye $3 d^{9} 4 s^{2}$ aana chahiye, lekin asli ground states $3 d^{5} 4 s^{1}$ aur $3 d^{10} 4 s^{1}$ hain. 3d aur 4s levels energy mein itne paas hain ki ek chhota sa bonus bhi balance badal sakta hai. Half-filled ( $d^{5}$ ) ya completely filled ( $d^{10}$ ) set ko yeh bonus milta hai: extra exchange energy aur symmetrical electron cloud. Ek electron ko 4s se 3d mein le jaane se yeh bonus bahut kam keemat par mil jaata hai.

Table 4.13d series ki ground-state configurations (argon core ke bahar)NCERT Table 4.1 · p. 90

Element	$Z$	Outer configuration
Sc	21	$3 d^{1} 4 s^{2}$
Ti	22	$3 d^{2} 4 s^{2}$
V	23	$3 d^{3} 4 s^{2}$
Cr	24	$3 d^{5} 4 s^{1}$ ( $3 d^{4} 4 s^{2}$ nahi)
Mn	25	$3 d^{5} 4 s^{2}$
Fe	26	$3 d^{6} 4 s^{2}$
Co	27	$3 d^{7} 4 s^{2}$
Ni	28	$3 d^{8} 4 s^{2}$
Cu	29	$3 d^{10} 4 s^{1}$ ( $3 d^{9} 4 s^{2}$ nahi)
Zn	30	$3 d^{10} 4 s^{2}$

3/3Copper bhi isi tarah poora $3 d^{10}$ set paata hai: $3 d^{10} 4 s^{1}$ .

Fig. 4.2Jab isse half-filled ya filled set poora hota hai, to ek 4s electron 3d mein chala jaata hai.NCERT p. 90

Do orbital box diagrams aamne-saamne, har ek mein paanch 3d boxes aur ek 4s box, jinmein electron arrows hain. Left mein chromium chaar single up-arrows 3d mein aur ek pair 4s mein ke saath shuru hota hai, jis par expected 3d4 4s2 likha hai. Doosre step mein 4s ka down-arrow khaali paanchve 3d box mein kood jaata hai aur up ho jaata hai, jisse chhe unpaired electrons ke saath 3d5 4s1 banta hai, jis par half-filled 3d likha hai. Right mein copper chaar paired 3d boxes, ek single aur ek 4s pair ke saath shuru hota hai; teesre step mein ek 4s electron single 3d box mein chala jaata hai, jisse 3d10 4s1 banta hai, jis par completely filled 3d likha hai.

4d aur 5d series mein surprises aur badh jaate hain, aur sab 'half ya full' rule follow nahi karte. Palladium sabse aage jaata hai: yeh apna outer s subshell poori tarah khaali kar deta hai ( $4 d^{10} 5 s^{0}$ ), aur aisa karne wala yeh akela d-block atom hai. Niobium ( $4 d^{4} 5 s^{1}$ ) aur ruthenium ( $4 d^{7} 5 s^{1}$ ) koi simple rule follow nahi karte; woh bas dikhate hain ki dono levels kitni baareeki se balanced hain. Table mein irregular cases diye gaye hain.

Table 4.24d aur 5d series ki irregular configurations: simple filling (expected) vs asli ground state (actual)NCERT p. 91

Element	Expected	Actual
Nb	$4 d^{3} 5 s^{2}$	$4 d^{4} 5 s^{1}$
Mo	$4 d^{4} 5 s^{2}$	$4 d^{5} 5 s^{1}$
Ru	$4 d^{6} 5 s^{2}$	$4 d^{7} 5 s^{1}$
Rh	$4 d^{7} 5 s^{2}$	$4 d^{8} 5 s^{1}$
Pd	$4 d^{8} 5 s^{2}$	$4 d^{10} 5 s^{0}$
Ag	$4 d^{9} 5 s^{2}$	$4 d^{10} 5 s^{1}$
Pt	$5 d^{8} 6 s^{2}$	$5 d^{9} 6 s^{1}$
Au	$5 d^{9} 6 s^{2}$	$5 d^{10} 6 s^{1}$

Har series ke right wale end par group 12 hai: zinc, cadmium, mercury aur copernicium, sab $(n - 1) d^{10} n s^{2}$ . Jab yeh metals react karte hain, to sirf apne s electrons dete hain, isliye unke ions mein bhi d set poora rehta hai. Yahi electron-based wajah hai ki IUPAC definition unhe bahar rakhti hai, halaanki hum unhe unke padosiyon ke saath padhte hain.

Do alag metals ke do aqueous ions dekho, $V^{2 +}$ aur $C r^{3 +}$ . Dono violet hain, dono mein teen unpaired electrons hain, aur dono $d^{3}$ hain. Yeh koi sanyog nahi hai. $(n - 1) d$ orbitals ek andar wale shell ke hain, phir bhi unke lobes atom ke kinare tak pahunchte hain. Wahan woh padosi atoms, ions aur molecules ko chhoote hain, aur woh bhi inhe chhoote hain. Isliye metal kaunsa hai, usse zyada aksar d electrons ki ginti tay karti hai ki ek ion kaisa dikhta hai aur kaisa behave karta hai.

Yeh periodic table ki ek jaani-pehchaani aadat ko ulta kar deta hai. s- aur p-blocks mein hum chemistry group-wise seekhte hain, kyunki ek column ke elements ek doosre jaise hote hain. d-block mein row ke saath padosi, jaise iron, cobalt aur nickel, aksar ek group ke members se zyada milte-julte hain. Unmein bas andar wale d subshell mein chhupe ek electron ka farak hota hai. Section 4.3 pehli row aur uski family wali khoobiyon ko follow karta hai: high melting points, kai oxidation states, paramagnetism, coloured ions, complexes aur catalysis.

Example 4.1NCERT Example 4.1 · p. 91

Gold haan, mercury nahi

Gold ( $Z = 79$ ) ka outer configuration $5 d^{10} 6 s^{1}$ hai aur mercury ( $Z = 80$ ) ka $5 d^{10} 6 s^{2}$ . Dono atoms ka 5d subshell poora bhara hai. Samjhao ki gold ko transition element kyun gina jaata hai lekin mercury ko nahi.

Pehle khud try karo. Phir solution ek-ek step karke kholo.

Quick check

3 mein se 1

Chromium (

Z = 24

) ka ground-state configuration kaunsa hai?

[A r] 3 d^{4} 4 s^{2}

[A r] 3 d^{6}

[A r] 3 d^{3} 4 s^{2} 4 p^{1}

[A r] 3 d^{5} 4 s^{1}

Answer dekho

Answer (D) $[A r] 3 d^{5} 4 s^{1}$

Ek 4s electron ko 3d mein le jaane se half-filled

3 d^{5}

set milta hai, aur yeh bonus chhoti si energy cost se bhaari padta hai. 'Expected'

3 d^{4} 4 s^{2}

lalchaane wala galat answer hai.

4.3 Transition Elements (d-Block) ki General Properties

Yahan se Section 4.4 ke end tak hum pehli row, scandium se zinc, ko follow karte hain, aur bhaari rows ko sirf comparison ke liye laate hain. Common baat simple hai: lagbhag har property jo hum dekhenge, is par depend karti hai ki atom ya ion mein kitne d electrons hain, aur woh kitni mazbooti se bandhe hain.

4.3.1 Physical Properties

Steel ka chammach, copper wire ya titanium ka chashme ka frame uthao, to tum ek typical transition metal pakde ho: yeh chamakta hai, heat aur electric current le jaata hai, tootne ke bajaye mud jaata hai, aur iska wire kheencha ja sakta hai. Room temperature par in mein se zyadatar metals apne atoms ko jaani-pehchaani metallic arrangements mein se kisi ek mein pack karte hain (body-centred cubic, hexagonal close-packed ya cubic close-packed). Manganese apna ek complicated cubic structure apnata hai, zinc aur cadmium thoda distorted hexagonal packing use karte hain, aur mercury to solid bhi nahi hai.

Sabse khaas baat hai ki yeh kitne mazboot hain. Zinc, cadmium aur mercury ko chhod do, to yeh scratch nahi hote, pighalne ke liye bahut high temperature chahiye, aur pighalne ke baad bhi mushkil se evaporate hote hain. Wajah bonding hai. s-block metal mein har atom apne sirf ek ya do s electrons ko electrons ke 'sea' ke saath share karta hai. Transition metal apne unpaired $(n - 1) d$ electrons bhi de sakta hai, aur padosi d orbitals overlap karke extra bonding dete hain. Enthalpy of atomisation (परमाणुकरण एन्थैल्पी), $Δ_{a} H^{\circ}$ , yaani ek mole solid ko free gaseous atoms mein badalne ke liye chahiye energy, is bond strength ko seedha naapti hai.

Table 4.33d metals ke melting points aur enthalpies of atomisation (rounded data-table values)NCERT p. 92

Metal	m.p. / K	$Δ_{a} H^{\circ}$ / kJ mol⁻¹
Sc	1814	378
Ti	1941	473
V	2183	514
Cr	2180	397
Mn	1519	281
Fe	1811	416
Co	1768	425
Ni	1728	430
Cu	1358	337
Zn	693	130

Table ko upar se neeche padho. Jaise-jaise unpaired d electrons ki ginti badhti hai, bond strength badhti hai, aur row ke beech ke paas peak karti hai, jahan har d orbital mein lagbhag ek unpaired electron hota hai. Uske baad electrons pair hone lagte hain aur bonding ke liye kam free bachte hain, isliye values phir girti hain. Manganese smooth curve ko todta hai: iski $3 d^{5} 4 s^{2}$ arrangement d electrons ko kaske pakadti hai, isliye woh metallic bonding mein kam yogdaan dete hain. Zinc, jiske saare d electrons paired aur andar dabe hain, sirf 4s se bond karta hai aur iski value sabse kam hai.

Bhaari rows aur bhi mazboot hain. Molybdenum aur tungsten ko atomise karne ke liye lagbhag $658$ aur $849 k J m o l^{- 1}$ chahiye, jabki unke upar wale chromium ko $397 k J m o l^{- 1}$ ; tungsten $3695 K$ par pighalta hai, kisi bhi doosre metal se zyada. Bade 4d aur 5d orbitals behtar overlap karte hain, isi wajah se 4d aur 5d compounds mein metal–metal bonds itne aksar milte hain. Bahut badi enthalpy of atomisation metal ko react karne se bhi rokti hai: platinum aur gold ka 'noble' character kuch hadd tak isi wajah se hai, jaisa Section 4.3.5 dikhata hai.

Example 4.2NCERT Example 4.2 · p. 95

Vanadium itna mazboot kyun juda rehta hai

Potassium, calcium aur vanadium ki enthalpies of atomisation lagbhag $89$ , $178$ aur $514 k J m o l^{- 1}$ hain. Teeno period 4 mein hain. Trend samjhao.

Pehle khud try karo. Phir solution ek-ek step karke kholo.

4.3.2 Transition Metals ke Atomic aur Ionic Sizes mein Variation

d-series mein aage badhne par har step nucleus mein ek proton aur $(n - 1) d$ subshell mein ek electron jodta hai. Ek hi d subshell ke electrons ek doosre ko kamzor screen karte hain, kyunki d orbitals alag-alag directions mein point karte hain. Isliye outer electrons ko dheere-dheere badhta effective nuclear charge mehsoos hota hai aur atoms chhote hote hain, lekin sirf dheere-dheere: metallic radius titanium ke $147 p m$ se nickel ke $125 p m$ tak girta hai. Same charge wale ions bhi row mein isi tarah chhote hote hain.

Group mein neeche jaane par hum ummeed karte hain ki atoms bade honge, kyunki har row ek poora naya shell jodti hai. 3d se 4d row tak aisa hota bhi hai. Lekin 4d se 5d row tak size mushkil se badalta hai: zirconium ka metallic radius $160 p m$ hai aur hafnium ka $159 p m$ . Lanthanum aur hafnium ke beech chaudah electrons 4f subshell mein jaate hain. 4f electrons d electrons se bhi kharab shield karte hain, isliye un chaudah elements mein atoms lagaatar sikudte hain. Yeh lanthanoid contraction us badhat ko lagbhag poori tarah cancel kar deta hai jo extra shell se honi chahiye thi (Fig. 4.3).

4/4Asal mein woh apne 4d partners ke barabar hain: lanthanoid contraction ne extra shell ko cancel kar diya hai.

Fig. 4.3Ek group ke 4d aur 5d members lagbhag same size ke hote hain.NCERT Fig. 4.3 · p. 94

Scale par bane circles ka ek grid. Upar ki row group 4 hai aur neeche ki row group 5; columns 3d, 4d aur 5d series hain. Pehle step mein sirf 3d atoms dikhte hain: titanium 147 picometres aur vanadium 135 picometres. Doosre step mein bade 4d atoms dikhte hain: zirconium 160 aur niobium 147 picometres. Teesre step mein 5d column ke dashed circles woh bada size dikhate hain jo hum hafnium aur tantalum ke liye expect karte. Aakhri step mein asli hafnium (159) aur tantalum (147) ke circles dikhte hain, 4d atoms jitne hi bade, aur unke beech equals sign hai.

Iske nateeje bade hain. Zirconium aur hafnium, ya niobium aur tantalum, size aur chemistry mein itne milte-julte hain ki woh ek hi minerals mein saath milte hain aur unhe alag karna bahut mushkil hai. Contraction 5d metals ko bahut dense bhi bana deta hai: osmium aur iridium, lagbhag $22.6 g c m^{- 3}$ ke saath, sabse dense known elements hain.

3d row mein har atom pichhle wale se thoda chhota lekin thoda bhaari hota hai, isliye har cubic centimetre mein zyada mass pack hota hai. Titanium ( $4.51 g c m^{- 3}$ ) itna halka hai ki aircraft frames aur artificial hips mein lagta hai, jabki copper $8.96 g c m^{- 3}$ tak pahunchta hai.

4.3.3 Ionisation Enthalpies

Nuclear charge badhne ke saath har d-series mein ionisation enthalpies bhi badhti hain, lekin main-group period ke mukable kahin dheere. Sodium se argon tak first ionisation enthalpy teen guna ho jaati hai; scandium ( $633 k J m o l^{- 1}$ ) se zinc ( $906 k J m o l^{- 1}$ ) tak yeh aadhe se bhi kam badhti hai. Naye 3d electrons 4s electron ke region ke andar baithte hain aur use extra protons se kaafi achhe se screen karte hain, isliye sabse bahar wale electron ko sirf dheere-dheere badhta pull mehsoos hota hai.

Ek rule bahut confusion bachata hai: jab 3d atom cation banata hai, to 4s electrons pehle nikalte hain. Atom charged hote hi 3d level energy mein 4s se neeche aa jaata hai. Isliye row ka har $M^{2 +}$ aur $M^{3 +}$ ion ek bare $[A r] 3 d^{n}$ ion hai, jismein koi 4s electron nahi.

Values irregular kyun hain? Teen factors subshell mein electron ki energy tay karte hain: nucleus ki taraf uska attraction, doosre electrons se uska repulsion, aur exchange energy (विनिमय ऊर्जा). Yeh ek stabilisation hai jo degenerate orbitals mein parallel spins wale electrons ko milta hai; Hund's rule ke peeche yahi quantum wajah hai. Yeh lagbhag parallel spins ke pairs ki ginti ke saath badhta hai:

Parallel spins ke pairs

N_{pairs} = \frac{p (p - 1)}{2}

(4.2)

jahan

$p$: degenerate orbitals ke ek set mein same spin wale electrons ki ginti

Definition

Exchange energy

Degenerate orbitals ke set mein parallel spin wale electrons ko milne wali extra stability; yeh lagbhag parallel-spin pairs ki ginti ke proportional hoti hai.

Example $d^{5}$ ion mein $5 \times 4 / 2 = 10$ pairs hain; $d^{4}$ ion mein sirf 6.

2/4Ek electron hatane par 6 pairs bachte hain: exchange stabilisation ke chaar pairs kho jaate hain, isliye yeh ionisation mehngi hai.

Fig. 4.4

d^{5}

se ek electron hatane par chaar parallel pairs toot jaate hain;

d^{6}

se ek hatane par ek bhi nahi.

Ek row mein paanch d-orbital boxes. Boxes ke neeche curved lines up-spin electrons ke har pair ko jodti hain. Pehle step mein paanchon boxes mein ek-ek up-arrow hai (Mn2+, d5) aur das jodne wale curves hain; counter par 10 parallel pairs likha hai. Doosre step mein ek electron hataya jaata hai (Mn3+, d4); usse jude chaar curves gayab ho jaate hain aur counter 6 dikhata hai, saath mein note 4 pairs gaye. Teesre step mein boxes mein paanch up-arrows aur pehle box mein ek down-arrow hai (Fe2+, d6), abhi bhi 10 pairs. Aakhri step mein down-arrow hataya jaata hai (Fe3+, d5); saare das curves bache rehte hain aur note kehta hai koi nahi.

Isse data ke saaf breaks samajh aate hain. Chromium aur copper ki second ionisation enthalpy kaafi zyada hai, kyunki $C r^{+}$ ( $3 d^{5}$ ) aur $C u^{+}$ ( $3 d^{10}$ ) ko ek stable set se electron dena padta hai. Manganese ki second value chromium se kam hai, kyunki $M n^{+}$ ( $3 d^{5} 4 s^{1}$ ) ke paas abhi bhi khone ke liye 4s electron hai. Third ionisation ke liye iron ( $2957 k J m o l^{- 1}$ ) ko extra proton ke bawajood manganese ( $3248 k J m o l^{- 1}$ ) se kam energy chahiye: Fig. 4.4 iski wajah dikhata hai. Zinc ki second value kam hai (yeh $d^{10}$ banata hai), lekin iski third value row mein sabse zyada hai, kyunki ise woh poora set todna padta hai.

To ionisation enthalpies kahani ka ek hissa batati hain ki kaunsi oxidation states tak pahunchna aasaan hai: nickel, copper aur zinc ki third values itni zyada hain ki woh shayad hi kabhi +2 se aage jaate hain. Poori kahani yeh nahi bata saktin, kyunki asli substance mein ion banne par energy release bhi hoti hai, hydration, crystal formation ya ligands se bonding ke through; Section 4.3.5 in terms ko saath jodta hai. Tab tak neeche ka explorer tumhe row mein numbers compare karne deta hai.

Interactive3d trends explorer

Scandium se zinc tak das 3d metals ka bar chart. Nau buttons plot hone wali property chunte hain: enthalpy of atomisation, first, second aur third ionisation enthalpies, metallic radius, do standard electrode potentials M2+/M aur M3+/M2+, density aur melting point. Jin bars ki reliable value nahi hai, woh gaps ki tarah dikhte hain. Bar par tap karne se element, units ke saath uski value, aur trend todne wale elements ke liye ek line ki explanation dikhti hai, jaise manganese ka half-filled 3d set ya zinc ka full 3d set. Chart ke neeche ek summary line batati hai ki chuni gayi property mein kaunsa pattern dhoondhna hai.

Fig. 4.5Scandium se zinc tak plot karne ke liye ek property chuno, phir value aur woh kyun alag hai padhne ke liye kisi bar par tap karo.

Quick check

3 mein se 1

Ek aur electron khone ke liye kis ion ko sabse zyada energy chahiye?

F e^{2 +}

(

d^{6}

)

C r^{2 +}

(

d^{4}

)

V^{2 +}

(

d^{3}

)

M n^{2 +}

(

d^{5}

)

Answer dekho

Answer (D) $M n^{2 +}$ ( $d^{5}$ )

M n^{2 +}

ko ionise karne se half-filled set toot jaata hai aur chaar exchange pairs kho jaate hain, isliye inmein manganese ki third ionisation enthalpy sabse zyada hai.

F e^{2 +}

lalchaane wala galat answer hai: usmein protons zyada hain, lekin uska chhatha electron paired hai aur aasaani se nikal jaata hai.

4.3.4 Oxidation States

Kisi chemist se transition metals ki ek khoobi poochho, to aksar jawab milega 'variable oxidation states'. Jaise vanadium +2, +3, +4 aur +5 mein milta hai, aur state badalne par uske compounds violet se green, phir blue, phir yellow ho jaate hain. States aam taur par ek unit se alag hoti hain, kyunki d electrons ek-ek karke dheere-dheere badhti keemat par hataye ja sakte hain. p-block mein steps aam taur par do ke hote hain: tin +2 aur +4 dikhata hai, thallium +1 aur +3, kyunki ns² pair ya to rehta hai (inert-pair effect) ya pair ki tarah hi jaata hai.

Har metal ki states plot karo (Fig. 4.6), to result ek pahaadi jaisa dikhta hai, jiske top par manganese hai: +2 se +7 tak har state. Left slope chadhna supply ka mamla hai. Metal zyada se zyada apne saare 4s aur 3d electrons de ya share kar sakta hai, isliye ceiling har step par ek badhti hai. Yeh $S c C l_{3}$ mein +3, $T i C l_{4}$ mein +4, $V_{2} O_{5}$ mein +5, $C r O_{3}$ mein +6 aur $K M n O_{4}$ mein +7 hai. Scandium ke paas aise sirf teen electrons hain aur woh hamesha teeno use karta hai, isliye uski state lagbhag badalti hi nahi.

Manganese ke baad supply badhti rehti hai lekin ceiling gir jaati hai. Iron ko +8 ke liye apne aathon outer electrons chahiye aur woh kabhi wahan nahi pahunchta, halaanki uske bhaari rishtedaar ruthenium aur osmium pahunchte hain ( $R u O_{4}$ , $O s O_{4}$ ). Iron ki roz ki states +2 aur +3 hain. Badhta nuclear charge d electrons ko aur kaske pakadta hai, aur jaise-jaise woh pair hote hain, bonds mein share karne ke liye kam half-empty orbitals bachte hain. Copper aur zinc tak d set lagbhag ya poora bhar jaata hai, aur bas +2 (copper ke liye +1 bhi) bachta hai.

3/3Roz ke compounds ki sabse common states squares se mark hain.

Fig. 4.63d metals ki oxidation states: maximum manganese par +7 tak badhta hai, phir girta hai.NCERT Table 4.3 · p. 96

Ek chart jiske neeche das 3d metals aur side mein oxidation states +1 se +7 hain. Pehle step mein line se jude filled blue dots har metal ki highest state mark karte hain: scandium se manganese tak 3, 4, 5, 6 aur 7, phir 6, 4, 4, 2 aur 2. Ek dashed grey line 4s plus 3d electrons ki ginti mark karti hai, jo manganese ke baad bhi badhti rehti hai jabki highest state girti hai. Doosre step mein open circles baaki saari known states jodte hain, aur titanium se manganese tak +2 se maximum tak har value bhar dete hain. Aakhri step mein orange squares sabse common states mark karte hain, jaise chromium ke liye +3 aur +6 aur manganese ke liye +2, +4 aur +7.

Group mein neeche jaane par d-block p-block ka ulta karta hai. Wahan bhaari elements lower states pakde rehte hain (lead +4 se zyada +2 pasand karta hai); yahan bhaari elements high states mein zyada aaraam se rehte hain. Chromium(VI) oxide, $C r O_{3}$ , reduce hone ko itna betaab hai ki ethanol mein aag laga sakta hai, phir bhi molybdenum(VI) aur tungsten(VI) ke oxides stable, unreactive solids hain.

Doosre extreme par, metal zero oxidation state mein bhi ho sakta hai. Nickel tetracarbonyl, $N i (C O)_{4}$ , ek volatile liquid jo nickel ko purify karne mein use hota hai, aur chromium hexacarbonyl, $C r (C O)_{6}$ , iske examples hain. CO ek khaas ligand hai: metal ko electron pair dene ke saath-saath yeh electron density ko apne khaali orbitals mein wapas le leta hai (yeh π-acceptor hai), jisse metal par bahut zyada negative charge jama nahi hota. Unit 5 yeh bonding samjhata hai.

Example 4.3NCERT Example 4.3 · p. 97

Titanium +4 par kyun ruk jaata hai

Titanium kabhi +4 se upar ki oxidation state nahi dikhata, lekin manganese +7 tak pahunchta hai. Samjhao.

Pehle khud try karo. Phir solution ek-ek step karke kholo.

4.3.5 $M^{2 +} / M$ Standard Electrode Potentials ke Trends

Standard electrode potential $E^{\circ} (M^{2 +} / M)$ batata hai ki metal kitni aasaani se apne aqueous dipositive ion mein badalta hai. Ise padhne ka ek useful tareeka hai ise teen energy steps ka final result maanna (Fig. 4.7): solid ko todkar atoms banao ( $Δ_{a} H^{\circ}$ , chadhaai), har atom se do electrons nikaalo ( $Δ_{i} H_{1} + Δ_{i} H_{2}$ , khadi chadhaai), aur water molecules ko ion ke chaaron taraf aane do (hydration enthalpy $Δ_{h y d} H^{\circ}$ , khadi utraai). Total jitna zyada chadhaai wala, change utna mushkil, aur $E^{\circ}$ utna kam negative (ya zyada positive) hota hai.

4/4Net: zinc +723, copper +940. Zyada chadhaai wala net change copper ko positive $E^{\circ}$ deta hai.

Fig. 4.7Metal ko aqueous ions mein badalna: copper ka net step zinc se lagbhag

217 k J m o l^{- 1}

zyada chadhaai wala hai (values kJ mol⁻¹ mein).NCERT Fig. 4.4 · p. 98

Do seedhi jaise energy diagrams aamne-saamne, left mein zinc aur right mein copper, same scale par. Pehle step mein ek chhota arrow solid metal se gaseous atom tak chadhta hai: zinc ke liye +130 kilojoules per mole aur copper ke liye +337. Doosre step mein ek lamba arrow gaseous 2+ ion tak chadhta hai: zinc ke liye +2639 aur copper ke liye +2703. Teesre step mein ek blue arrow hydrated ion tak utarta hai: zinc ke liye minus 2046 aur copper ke liye minus 2100. Aakhri step mein ek dashed arrow solid metal ko hydrated ion se jodta hai: net change zinc ke liye +723 aur copper ke liye +940 hai, isliye copper ka final level upar hai.

Yeh cycle overall trend samjhata hai: row mein aage dono ionisation steps mehnge hote jaate hain, isliye $E^{\circ}$ lagaatar kam negative hota jaata hai. Yeh copper ki anokhi baat bhi samjhata hai. Copper akela 3d metal hai jiska $E^{\circ} (M^{2 +} / M)$ positive ( $+ 0.34 V$ ) hai: ise atomise hone mein bahut keemat chukaani padti hai aur $C u^{+}$ ke $3 d^{10}$ set se second electron khone mein aur bhi zyada, aur hydration yeh wapas nahi chuka paata. Copper ko dilute hydrochloric ya sulphuric acid mein daalo, to hydrogen ke bubbles nahi aate. Ise ghulane ke liye aisa acid chahiye jo khud oxidising agent ho, jaise nitric acid ya garam, concentrated sulphuric acid; tab copper $H^{+}$ ko reduce karne ke bajaye acid ko reduce karta hai (nitrogen oxides ya sulphur dioxide mein).

Teen values smooth trend se neeche hain, padosiyon ke hisaab se jitni honi chahiye usse zyada negative:

Manganese: $M n^{2 +}$ ek half-filled $d^{5}$ ion hai, aur manganese ko atomise karna aasaan hai.
Zinc: $Z n^{2 +}$ ek full $d^{10}$ ion hai, aur zinc ki enthalpy of atomisation row mein sabse kam hai.
Nickel: hydration step kaafi zyada energy deta hai, kyunki chhota $N i^{2 +}$ ion water molecules ko bahut mazbooti se pakadta hai.

4.3.6 $M^{3 +} / M^{2 +}$ Standard Electrode Potentials ke Trends

$M^{3 +} / M^{2 +}$ couple +3 aur +2 states ko seedha compare karta hai. Kam ya negative $E^{\circ}$ ka matlab hai ki $M^{2 +}$ ion aasaani se electron de deta hai (reducing agent); bada positive value matlab $M^{3 +}$ ion utsukta se electron pakadta hai (oxidising agent). Har value d-electron count se padhi ja sakti hai.

Scandium: $S c^{3 +}$ ka khaali $d^{0}$ (argon) configuration hai, isliye $S c^{2 +}$ lagbhag exist hi nahi karta; value bahut kam hai.
Vanadium ( $- 0.26 V$ ) aur chromium ( $- 0.41 V$ ): $V^{2 +}$ aur $C r^{2 +}$ reducing hain. $C r^{2 +}$ ( $d^{4}$ ) khaas taur par $C r^{3 +}$ ( $d^{3}$ ) banne ko utsuk hai, jiske teen d electrons complex mein lower-energy d set (Unit 5 ka $t_{2 g}$ set) ko theek aadha bharte hain.
Manganese ( $+ 1.54 V$ ): $M n^{3 +}$ ( $d^{4}$ ) ek electron lekar half-filled $d^{5}$ $M n^{2 +}$ ban jaata hai, isliye yeh strong oxidising agent hai.
Iron ( $+ 0.77 V$ ): $F e^{2 +}$ ( $d^{6}$ ) ek electron khokar half-filled $d^{5}$ tak pahunchta hai, isliye value comparatively kam hai.
Cobalt ( $+ 1.92 V$ ): $C o^{3 +}$ itna strongly oxidising hai ki water mein yeh dheere-dheere khud water ko oxidise kar deta hai.
Zinc: $Z n^{3 +}$ ion ke liye $d^{10}$ set todna padta; yeh unknown hai.

Example 4.4NCERT Example 4.4 · p. 98

Do d⁶ ions, ulta behaviour

$F e^{2 +}$ aur $C o^{3 +}$ dono mein chhe d electrons hain. Water mein $F e^{2 +}$ ek mild reducing agent hai lekin $C o^{3 +}$ ek powerful oxidising agent hai ( $E^{\circ}$ : $F e^{3 +} / F e^{2 +} = + 0.77 V$ , $C o^{3 +} / C o^{2 +} = + 1.92 V$ ). Samjhao.

Pehle khud try karo. Phir solution ek-ek step karke kholo.

4.3.7 Higher Oxidation States ki Stability ke Trends

High oxidation states ko aise partners chahiye jo electron density ko zor se apni taraf kheench sakein. Sabse achhe do hain fluorine aur oxygen, dono chhote aur highly electronegative. Har metal ka highest fluoride aur highest oxide compare karne se pata chalta hai ki har partner metal ko kitna aage le ja sakta hai.

Table 4.4Har 3d metal ka highest fluoride aur highest oxide (brackets mein metal ki oxidation state)NCERT Tables 4.5, 4.6 · p. 99

Metal	Highest fluoride	Highest oxide
Ti	$T i F_{4}$ (+4)	$T i O_{2}$ (+4)
V	$V F_{5}$ (+5)	$V_{2} O_{5}$ (+5)
Cr	$C r F_{5}$ (+5)	$C r O_{3}$ (+6)
Mn	$M n F_{4}$ (+4)	$M n_{2} O_{7}$ (+7)
Fe	$F e F_{3}$ (+3)	$F e_{2} O_{3}$ (+3)
Co	$C o F_{3}$ (+3)	$C o_{3} O_{4}$ (mixed +2, +3)
Ni	$N i F_{2}$ (+2)	$N i O$ (+2)
Cu	$C u F_{2}$ (+2)	$C u O$ (+2)

Yahi do partners kyun jeette hain? High oxidation state wale metal par bada positive charge hota hai. Use rakhne wala compound tabhi stable hai jab bahut energy wapas mile: compound ionic ho to badi lattice energy, jaise $C o F_{3}$ , ya molecular ho to strong bonds, jaise $V F_{5}$ . Chhota, highly electronegative fluorine dono deta hai. Phir bhi table ka fluoride column uski limits dikhata hai, aur baaki halogens aur bhi peeche hain:

Fluorine kahan rukta hai. Yeh sirf vanadium tak group number ke barabar chalta hai: $S c F_{3}$ , $T i F_{4}$ , $V F_{5}$ . Chromium ka highest fluoride $C r F_{5}$ hai, aur manganese ka sirf $M n F_{4}$ . Manganese(VII) fluorine se sirf oxygen ki madad se milta hai, oxofluoride $M n O_{3} F$ mein. Iron se aage koi simple fluoride +3 se aage nahi jaata, aur $C o F_{3}$ cobalt(III) ka akela halide hai.
Bhaari halogens aur peeche hain. Chlorine, bromine aur iodine akele vanadium ko +5 par nahi rakh sakte; vanadium(V) unke saath sirf oxohalides, $V O X_{3}$ , mein milta hai.
Iodide aur high states mein takkar. Iodide aasaani se oxidise hota hai, isliye strongly oxidising metal ion use khatam kar deta hai. Copper(II) iodide exist nahi karta: $C u^{2 +}$ mein iodide daalne par white copper(I) iodide aur free iodine milte hain.
Fluoride aur low states mein bhi takkar. Copper(I) fluoride unknown hai, halaanki copper(I) chloride, bromide aur iodide jaane-pehchaane solids hain.

Neeche likha copper(II)–iodide reaction analysis mein kaam aata hai: isse nikli iodine ko thiosulphate se titrate karke pata chalta hai ki kisi alloy ya ore mein kitna copper hai.

\begin{aligned} 2 C u^{2 +} + 4 I^{-} \\ \overset{}{\to} 2 C u I (s) \\ + I_{2} \end{aligned}

(4.3)

$C u I$ aur $C u_{2} O$ jaise solid copper(I) compounds stable hain, phir bhi $C u^{+}$ ion water mein tik nahi sakta. Yeh disproportionate hota hai: har do ions mein se ek $C u^{2 +}$ banta hai aur doosra copper metal (Example 4.9 isko number deta hai). Faisla water karta hai. Doubly charged ion water molecules ko singly charged ion se kahin zyada zor se kheenchta hai, aur $C u^{2 +}$ ke hydration se nikli energy copper ka second electron hatane ki keemat se zyada hoti hai.

Oxygen aur bhi aage jaata hai. Oxide column mein neeche highest state $M n_{2} O_{7}$ (+7) tak group number ke saath chalti hai, manganese ke best fluoride se teen units upar. Zaroori partners gino. Ek fluorine atom ek bond banata hai, isliye manganese(VII) ko ek chhote atom ke chaaron taraf saat fluorine atoms thoonsne padte. Ek doubly bonded oxygen metal ke do electrons ka hisaab rakhta hai, isliye chaar oxygen atoms kaafi hain, aur woh tetrahedron ke corners par aaraam se fit ho jaate hain.

Yeh tetrahedral $M O_{4}$ unit high states ki pehchaan hai. Yeh vanadate ( $V O_{4}^{3 -}$ , V +5), chromate ( $C r O_{4}^{2 -}$ , Cr +6), manganese oxoanions $M n O_{4}^{3 -}$ , $M n O_{4}^{2 -}$ aur $M n O_{4}^{-}$ (+5, +6 aur +7), aur khud $M n_{2} O_{7}$ mein dikhta hai, jo aise do tetrahedra hain jo ek corner oxygen share karte hain. Manganese ke baad oxygen ki madad bhi kaafi nahi rehti. Iron ka highest ordinary oxide $F e_{2} O_{3}$ hai, aur iron(VI) sirf ferrate ion, $F e O_{4}^{2 -}$ , ke roop mein exist karta hai, jo strong alkali mein kuch der tikta hai aur phir $F e_{2} O_{3}$ aur oxygen mein toot jaata hai. Acid solution mein chhote oxocations bhi high states sambhalte hain: $T i O^{2 +}$ (+4), blue $V O^{2 +}$ (+4) aur pale yellow $V O_{2}^{+}$ (+5).

Example 4.5NCERT Example 4.5 · p. 100

Kaunsa oxoion chloride ko oxidise kar sakta hai?

Acid solution mein $E^{\circ}$ $V O_{2}^{+} / V O^{2 +}$ ke liye $+ 1.00 V$ , $C r_{2} O_{7}^{2 -} / C r^{3 +}$ ke liye $+ 1.33 V$ aur $M n O_{4}^{-} / M n^{2 +}$ ke liye $+ 1.51 V$ hai, jabki $E^{\circ} (C l_{2} / C l^{-}) = + 1.36 V$ . (a) Standard conditions mein teen oxoions mein se kaunsa chloride ions ko oxidise kar sakta hai? (b) Vanadium se manganese tak oxidising power kyun badhti hai?

Pehle khud try karo. Phir solution ek-ek step karke kholo.

4.3.8 Chemical Reactivity aur $E^{\circ}$ Values

Iron ka ek tukda aur titanium ka ek tukda thande dilute hydrochloric acid mein daalo. Iron mein bubbles uthte hain, lekin titanium achhoota dikhta hai, halaanki uska $E^{\circ} (M^{2 +} / M)$ ( $- 1.63 V$ ) iron ( $- 0.44 V$ ) se kahin zyada negative hai. Electrode potentials sirf ek sawaal ka jawab dete hain: reaction ho sakta hai ya nahi. Woh kitni tezi se hota hai, yeh alag baat hai, aur titanium, vanadium ki tarah, ek patli, mazboot oxide film se protected hai jo thande, non-oxidising acids ko metal se door rakhti hai. Sirf $E^{\circ}$ se dekho, to copper ko chhod kar pehli row ka har metal $1 M$ $H^{+}$ mein ghul jaana chahiye. Block mein aur neeche, platinum aur gold har single acid ko jhel lete hain aur sirf aqua regia jaise mixtures mein ghulte hain.

Section 4.3.6 ki $M^{3 +} / M^{2 +}$ values ions ko isi tarah sort karti hain. Ek extreme par $T i^{2 +}$ , $V^{2 +}$ aur $C r^{2 +}$ itne strong reducing agents hain ki $H^{+}$ se bhi electrons le lete hain, isliye unke acidified solutions dheere-dheere hydrogen chhodte hain. Doosre extreme par $M n^{3 +}$ aur $C o^{3 +}$ row ke aqua ions mein sabse strong oxidising agents hain. Beech mein $F e^{2 +}$ aur $F e^{3 +}$ water mein aaraam se saath rehte hain. Chromium(II) ke liye:

\begin{aligned} 2 C r^{2 +} (a q) \\ + 2 H^{+} (a q) \\ \overset{}{\to} 2 C r^{3 +} (a q) \\ + H_{2} (g) \end{aligned}

(4.4)

Example 4.6NCERT Example 4.6 · p. 101

Copper ki nobility ko number dena

Yeh rounded data (kJ mol⁻¹) use karke difference $E^{\circ} (C u^{2 +} / C u) - E^{\circ} (Z n^{2 +} / Z n)$ estimate karo: $Δ_{a} H^{\circ}$ : Zn 130, Cu 337; $Δ_{i} H_{1} + Δ_{i} H_{2}$ : Zn 2639, Cu 2703; $Δ_{h y d} H^{\circ} (M^{2 +})$ : Zn −2046, Cu −2100. $Δ G \approx Δ H$ maano (entropy ignore karo).

Pehle khud try karo. Phir solution ek-ek step karke kholo.

Example 4.7NCERT Example 4.7 · p. 101

Protons zyada, phir bhi ionise karna aasaan

Iron mein manganese se ek proton zyada hai, phir bhi iski third ionisation enthalpy kam hai (Fe $2957$ , Mn $3248 k J m o l^{- 1}$ ), aur $E^{\circ} (F e^{3 +} / F e^{2 +}) = + 0.77 V$ , $E^{\circ} (M n^{3 +} / M n^{2 +}) = + 1.54 V$ se kahin neeche hai. Dono facts samjhao.

Pehle khud try karo. Phir solution ek-ek step karke kholo.

Quick check

2 mein se 1

Inmein se kaunsa ion dilute acid se hydrogen nikalega?

F e^{3 +}

M n^{2 +}

C u^{2 +}

C r^{2 +}

Answer dekho

Answer (D) $C r^{2 +}$

C r^{2 +}

ek strong reducing agent hai (

E^{\circ} (C r^{3 +} / C r^{2 +}) = - 0.41 V

), isliye yeh

H^{+}

H_{2}

mein reduce kar sakta hai, jaisa (4.4) mein hai. Baaki pehle se stable hain ya oxidising hain.

4.3.9 Magnetic Properties

Ek salt ki chhoti tube ko strong electromagnet ke poles ke beech latkao aur switch on karo (Fig. 4.8). Zyadatar transition metal salts field ke andar kheeche jaate hain: woh paramagnetic (अनुचुंबकीय) hain. Kuch, jaise zinc salts, halke se field se bahar dhakele jaate hain: woh diamagnetic hain. Iron, cobalt aur nickel metals kahin zyada zor se respond karte hain, kyunki padosi atoms ke chhote-chhote magnets ek saath line up ho jaate hain; woh strongly attract hote hain aur magnetised reh sakte hain. Yeh ferromagnetism asal mein paramagnetism hi hai, jo atoms ke poore regions ke milkar kaam karne se kai guna badh jaata hai.

Definition

Paramagnetic

Magnetic field ke andar kheencha jaata hai, kyunki substance mein unpaired electrons hote hain jinke magnetic moments field ke saath line up ho jaate hain.

Example $C u S O_{4} \cdot 5 H_{2} O$ ( $C u^{2 +}$ $d^{9}$ hai).

Definition

Diamagnetic

Magnetic field se halka sa repel hota hai; iske saare electrons paired hote hain.

Example $Z n S O_{4} \cdot 7 H_{2} O$ ( $Z n^{2 +}$ $d^{10}$ hai).

Yeh pull aata kahan se hai? Ek unpaired electron chhote bar magnet ki tarah behave karta hai, kuch apne spin ki wajah se aur kuch nucleus ke around apni motion ki wajah se, jabki do paired electrons ek doosre ko cancel kar dete hain. Pehli row ke metals ke compounds mein ligands orbital motion ko kaafi had tak jakad dete hain (chemists kehte hain yeh quenched hai), isliye lagbhag saara magnetism spins se aata hai. Tab spin-only magnetic moment sirf $n$ , yaani unpaired electrons ki ginti, par depend karta hai:

Spin-only formula

μ = \sqrt{n (n + 2)} B M

(4.5)

jahan

$n$: unpaired electrons ki ginti
$B M$: Bohr magneton, electron ke magnetic moment ki natural unit, $9.27 \times 10^{- 24} J T^{- 1}$

Table 4.5Spin-only magnetic moments (examples ke roop mein high-spin aqua ions)NCERT Table 4.7 · p. 102

$n$	$μ$ / BM	Examples
0	0	$S c^{3 +}$ , $C u^{+}$ , $Z n^{2 +}$
1	1.73	$T i^{3 +}$ , $C u^{2 +}$
2	2.83	$V^{3 +}$ , $N i^{2 +}$
3	3.87	$V^{2 +}$ , $C r^{3 +}$ , $C o^{2 +}$
4	4.90	$C r^{2 +}$ , $M n^{3 +}$ , $F e^{2 +}$
5	5.92	$M n^{2 +}$ , $F e^{3 +}$

Pehli row ke zyadatar ions ke measured moments in values ke kareeb hote hain, isliye magnetic measurement unpaired electrons ginne ka ek jaldi wala tareeka hai; sabse chhota non-zero moment, 1.73 BM, ka matlab theek ek. Jahan measured value zyada hai, wahan kuch orbital motion bachi rehti hai: aqueous $F e^{2 +}$ lagbhag $5.4 B M$ dikhata hai aur $C o^{2 +}$ lagbhag $4.4$ se $5.2 B M$ ke beech, dono apni spin-only values se zyada. Fig. 4.8 ka balance aise moments naapne ka tareeka hai.

2/3 $M n^{2 +}$ ( $d^{5}$ , paanch unpaired electrons) field mein kheencha jaata hai: reading badhti hai.

Fig. 4.8Paramagnetic sample field mein kheencha jaata hai aur zyada bhaari lagta hai; diamagnetic sample bahar dhakela jaata hai aur halka lagta hai.

Upar ek digital balance wire se ek lambi sample tube pakde hue hai. Tube ka neeche wala hissa electromagnet ke north aur south poles ke beech latka hai. Pehle step mein magnet off hai aur display par same likha hai. Doosre step mein dashed field lines poles ko jodti hain; manganese(II) salt wali tube neeche field mein kheench li jaati hai aur display par bhaari likha hai. Teesre step mein uski jagah zinc(II) salt use hota hai; tube thoda sa field se upar uthti hai aur display par halka likha hai.

Neeche ka explorer tumhe koi bhi 3d atom ya ion banane deta hai, dekho kaise uske electrons Hund's rule se orbital boxes bharte hain, aur unpaired electrons aur spin-only moment padh lo.

Interactived-electron explorer

Paanch 3d boxes aur ek 4s box wala orbital box diagram. Das buttons scandium se zinc tak element chunte hain aur paanch buttons 0 se +4 tak charge chunte hain; jo charges argon core todte, woh disabled hain. Boxes Hund's rule ke hisaab se up aur down arrows se bharte hain, aur configuration likh kar dikhaya jaata hai, neutral atoms ke liye chromium aur copper ke exceptions ke saath. Readouts d electrons ki ginti, unpaired electrons, parallel spins ke pairs, Bohr magnetons mein spin-only magnetic moment, ion paramagnetic hai ya diamagnetic, aur kya woh d–d colour dikha sakta hai, yeh batate hain; jahan common aqua ion hai, wahan uska observed colour bhi. Ek note half-filled aur filled sets jaise special cases samjhata hai.

Fig. 4.9Sc se Zn tak ek element aur ek charge chuno. 4s electrons pehle nikalte hain; phir unpaired electrons, spin-only moment aur ion coloured hona chahiye ya nahi, padho.

Example 4.8NCERT Example 4.8 · p. 102

Vanadium ion pehchaano

Ek vanadium compound ka measured magnetic moment $2.8 B M$ hai. Unpaired electrons ki ginti aur vanadium ki likely oxidation state nikaalo.

Pehle khud try karo. Phir solution ek-ek step karke kholo.

Quick check

3 mein se 1

Water mein

N i^{2 +}

(

Z = 28

) ka spin-only magnetic moment kitna hai, BM mein?

Answer dekho

Answer 2.83 BM

N i^{2 +}

[A r] 3 d^{8}

hai: teen filled orbitals aur do half-filled, isliye

n = 2

aur

μ = \sqrt{2 \times 4} = 2.83 B M

4.3.10 Coloured Ions ka Banna

Transition metal salts ke solutions paint box jaise dikhte hain: blue copper sulphate, green nickel chloride, pink cobalt nitrate. Water molecules (ya doosre ligands) se ghire ion mein paanchon d orbitals ki energies barabar nahi rehtin; woh ek lower aur ek upper set mein split ho jaate hain (Unit 5 iski wajah samjhata hai). Lower set ka electron upper set mein jump kar sakta hai agar woh theek sahi energy ki light absorb kare, yeh hai d–d transition. Zyadatar ions ke liye yeh energy visible range mein aati hai.

Hum woh light dekhte hain jo absorb nahi hoti, isliye solution ka colour absorbed colour ka complement hota hai (Fig. 4.10). Energy gap ka size metal, uske charge aur uske ligands par depend karta hai, isliye ligands badalne par same metal ka colour badal sakta hai: aqueous $C u^{2 +}$ halka blue hai, lekin ammonia daalo to $[C u (N H_{3})_{4}]^{2 +}$ banne se gehra blue-violet ho jaata hai. Jis ion mein koi d electron nahi ( $S c^{3 +}$ , $T i^{4 +}$ ) ya poora set hai ( $Z n^{2 +}$ , $C u^{+}$ ), usmein koi d–d jump possible nahi, isliye uske compounds white aur solutions colourless hote hain.

3/4Aar-paar nikli light mein yellow-green nahi hota, isliye solution purple dikhta hai.

Fig. 4.10Ion d electron ko upar uthane ke liye visible light ka ek band absorb karta hai; solution bacha hua, complementary colour dikhata hai.NCERT p. 103

Left mein ek energy diagram dikhata hai ki water mein ion ke d orbitals teen ke lower set aur do ke upper set mein split hain, jinke beech delta naam ka energy gap hai. Beech mein white light ka ek band, chhe coloured stripes ki tarah bana, Ti3+ solution wale beaker mein jaata hai. Pehle step mein electron lower set mein hai. Doosre step mein woh upper set mein jump karta hai, aur beaker se nikalti light ki yellow aur green stripes gayab hain, jis par yellow-green absorbed likha hai. Teesre step mein right mein ek aankh bachi hui light dekhti hai, jis par dikhe purple likha hai. Aakhri step mein beaker mein Sc3+ hai, jismein koi d electron nahi: kuch absorb nahi hota, chhaon stripes nikal jaati hain aur aankh ise colourless dekhti hai.

Table 4.63d series ke kuch aqua ions ke colours, d electrons ki ginti ke hisaab seNCERT Table 4.8 · p. 103

$d^{n}$	Water mein ion	Colour
$d^{0}$	$S c^{3 +}$ , $T i^{4 +}$	colourless
$d^{1}$	$T i^{3 +}$	purple
$d^{1}$	$V O^{2 +}$ (V +4)	blue
$d^{2}$	$V^{3 +}$	green
$d^{3}$	$V^{2 +}$ , $C r^{3 +}$	violet
$d^{4}$	$C r^{2 +}$	blue
$d^{5}$	$M n^{2 +}$	bahut halka pink
$d^{5}$	$F e^{3 +}$	yellow (hydrolysis se)
$d^{6}$	$F e^{2 +}$	halka green
$d^{7}$	$C o^{2 +}$	pink
$d^{8}$	$N i^{2 +}$	green
$d^{9}$	$C u^{2 +}$	blue
$d^{10}$	$Z n^{2 +}$	colourless

4.3.11 Complex Compounds ka Banna

Blood ka laal rang ek complex se aata hai. Haemoglobin mein har iron(II) ion ko ek flat ring ke chaar nitrogen atoms aur protein ka ek paanchva nitrogen pakadte hain, aur ek chhathi position bachti hai jahan oxygen molecule jud sakta hai. Complex aisi hi koi unit hai: ek central metal ion jisse kai molecules ya anions, yaani ligands, bonded hain, aur jo apne colour, charge aur reactions wali nayi species ki tarah behave karti hai. Transition metals inhe bahut badi sankhya mein banate hain, jaise $[C o (N H_{3})_{6}]^{3 +}$ , $[N i (C N)_{4}]^{2 -}$ , $[F e (H_{2} O)_{6}]^{2 +}$ aur $[A g (N H_{3})_{2}]^{+}$ , jo Tollens' reagent ka silver complex hai; vitamin B $_{12}$ ek cobalt complex ke around bana hai.

Transition metal ions itne achhe host kyun hain? Har ligand electrons ka ek pair donate karta hai, isliye best hosts woh hain jo electron pairs ko zor se kheenchein aur unhe rakhne ki jagah ho. Transition metal ions chhote aur aksar highly charged hote hain, jisse unka pull strong hota hai, aur unke paas pairs accept karne ke liye suitable energy ke khaali d orbitals hote hain. Unit 5 poori tarah in compounds par hai.

4.3.12 Catalytic Properties

Transition metal catalysts tumhare chaaron taraf hain. Car ke catalytic converter mein platinum, palladium aur rhodium ki patli film carbon monoxide, unburnt fuel aur nitrogen oxides ko carbon dioxide, water aur nitrogen mein badal deti hai. Nitric acid plants mein platinum–rhodium alloy ki gauze ammonia ko oxidise karti hai, aur us enzyme ke centre mein molybdenum aur iron atoms hain jisse soil bacteria nitrogen fix karte hain. (Section 4.7 mein aur industrial examples hain.) Catalyst reaction ko ek aasaan raasta deta hai, aur transition metals yeh do tareekon se de sakte hain.

Milne ki jagah. Reactants ke molecules catalyst surface ke metal atoms se chipak jaate hain, aur metal ke 3d aur 4s electrons use karke temporary bonds banate hain. Paas-paas pakde rehne se reactants kahin zyada baar milte hain, aur unke andar ke bonds khinchkar kamzor ho jaate hain, isliye kam activation energy chahiye.
Electron shuttle. Jo ion do oxidation states ke beech aasaani se switch karta hai, woh ek reactant se electrons lekar doosre ko de sakta hai, aur kam energy wala raasta khol deta hai.

Doosri tarah ka ek saaf example hai peroxodisulphate se iodide ka oxidation. Dono reactants negative ions hain jo ek doosre ko repel karte hain, isliye direct reaction slow hai. $F e^{3 +}$ ki thodi si matra electrons shuttle karke ise tez kar deti hai (Fig. 4.11):

overall

\begin{aligned} S_{2} O_{8}^{2 -} + 2 I^{-} \\ \overset{}{\to} 2 S O_{4}^{2 -} \\ + I_{2} \end{aligned}

do catalysed steps

\begin{aligned} 2 F e^{3 +} + 2 I^{-} \\ \overset{}{\to} 2 F e^{2 +} + I_{2} \\ 2 F e^{2 +} + S_{2} O_{8}^{2 -} \\ \overset{}{\to} 2 F e^{3 +} \\ + 2 S O_{4}^{2 -} \end{aligned}

4/4Iron regenerate ho jaata hai, isliye thodi si matra kaam karti rehti hai.

Fig. 4.11Iron +3 aur +2 ke beech switch karta hai, aur electrons iodide se peroxodisulphate tak le jaata hai.NCERT p. 104

Pehle step mein do negative ions, iodide aur peroxodisulphate, aamne-saamne hain, aur ek double-headed arrow par repel: slow likha hai. Baad ke steps mein ek gol cycle dikhta hai jiske top par 2Fe3+ aur bottom par 2Fe2+ hai. Doosre step mein circle ka left half highlight hota hai: iodide left se aata hai aur iodine bankar nikalta hai, jabki Fe3+ Fe2+ ban jaata hai. Teesre step mein right half highlight hota hai: peroxodisulphate aata hai aur do sulphate ions bankar nikalta hai, jabki Fe2+ wapas Fe3+ ban jaata hai. Aakhri step mein dono halves highlight hain aur centre mein catalyst wapas likha hai.

4.3.13 Interstitial Compounds ka Banna

Steel thode se carbon wala iron hai, aur woh carbon atoms iron atoms ki jagah nahi lete: woh packed iron atoms ke beech ke chhote gaps mein ghus jaate hain. Hydrogen, boron, carbon aur nitrogen atoms itne chhote hain ki aisa kar sakein. Yeh kai transition metals ke saath interstitial compounds (अंतराकाशी यौगिक) banate hain: tungsten carbide ( $W C$ ), titanium nitride ( $T i N$ ), cementite ( $F e_{3} C$ ) aur palladium hydride ( $P d H_{x}$ , jiska $x$ lagbhag 0.7 tak pahunch sakta hai).

Definition

Interstitial compound

Aisa compound jismein H, B, C ya N jaise chhote atoms metal ke crystal lattice ke holes mein baithe hote hain; iska composition aksar variable hota hai aur yeh metal ka kaafi character bana kar rakhta hai.

ExampleTungsten carbide, $W C$ , jo drill tips mein use hota hai.

Kitne guests hain, yeh is par depend karta hai ki kitne holes bhare hain. Isliye formulas aksar fractional hote hain (jaise $P d H_{0.7}$ ) aur metal ki oxidation state ke baare mein kuch nahi batate, aur bonding mixed hoti hai, kuch metallic aur kuch covalent. Guest atoms wedges ki tarah kaam karte hain jo metal atoms ki layers ko ek doosre par phisalne se rokte hain, aur isi se samajh aata hai ki yeh materials kis kaam ke hain:

yeh bahut hard hote hain; kuch carbides aur borides diamond ke kareeb pahunchte hain, isliye cutting tools ki tips tungsten carbide ki hoti hain aur drill bits par sunehre rang ki $T i N$ coating hoti hai;
yeh parent metal se zyada temperature par pighalte hain;
yeh chemical attack jhel lete hain;
phir bhi yeh metals ki tarah electricity conduct karte hain.

2/3C ya N jaise chhote atoms holes mein ghus jaate hain, jisse solid zyada hard aur high-melting ho jaata hai.

Fig. 4.12Chhote atoms holes bharte hain (interstitial compounds); same size ke atoms jagah badalte hain (substitutional alloys).NCERT p. 104

Bees bade circles ka ek square array layers mein packed metal atoms dikhata hai. Pehle step mein us par pure metal likha hai. Doosre step mein chaar bade atoms ke beech ke kuch gaps mein chhote dark circles dikhte hain, jin par likha hai interstitial: chhote H, C, N holes mein ghuse, harder, inert. Teesre step mein chhote atoms chale jaate hain aur chaar bade circles dashed orange outline ke saath bane hain, jin par likha hai alloy: same size ka metal kuch jagah leta, aur dashed: naya.

4.3.14 Alloy Formation

India ke ₹1 aur ₹2 ke coins, stainless-steel ka sink aur brass ka diya, sab alloys (मिश्रातु) hain: aise metallic materials jo ek metal ko doosre elements ke saath pighla kar banaye jaate hain. Sabse simple tarah, substitutional alloy, mein mile hue metal ke atoms crystal mein host ki kuch jagahein random taur par le lete hain. Yeh tabhi chalta hai jab dono tarah ke atoms size mein kareeb hon, metallic radius mein lagbhag 15 % ke andar, aur transition metals apne milte-julte radii aur bonding ki wajah se bahut aasaani se mix ho jaate hain. Chromium ( $129 p m$ ) iron ( $126 p m$ ) se lagbhag 2 % alag hai, aur zinc ( $137 p m$ ) copper ( $128 p m$ ) se lagbhag 7 %.

Definition

Alloy

Ek metal ko ek ya zyada doosre elements ke saath milaakar bana metallic material; substitutional alloy mein same size ke atoms lattice mein ek doosre ki jagah le lete hain.

ExampleStainless steel: lagbhag 18 % chromium aur 8 % nickel wala iron.

Alloying aam taur par metal ko zyada hard banata hai, aur aksar uska melting point badha deta hai. Steels dikhate hain ki kuch per cent kitna kar sakta hai. Chromium aur nickel stainless steel dete hain, tungsten aur vanadium tool steels ko laal-garam hone par bhi hard rakhte hain, aur manganese railway crossings ka mazboot steel banata hai. Transition metals main-group metals ke saath bhi alloy banate hain. Copper aur zinc se lamps aur fittings ka brass banta hai, aur copper aur tin se bronze, yaani paramparik thaliyon aur katoriyon ka kansa bell-metal. Thode copper ke saath zinc-rich alloy Karnataka ke Bidri ware ka base hai, jismein silver ki inlay hoti hai.

Try karke dekho

Kya alloy ko jang lagta hai?

Tumhe chahiye

ek iron nail aur sandpaper ka ek tukda
stainless-steel ka chammach ya ₹1 ka sikka
do chhote cups, paani aur namak

Pehle guess karo

Kis sample par pehle jang dikhega?

Stainless-steel ke chammach par, kyunki usmein zyada metals hainIron nail parDono par ek saathKisi par nahi: namak wala paani jang nahi lagata

Ek aam iron nail ko halka sa sandpaper se ragdo taaki uski surface par khula metal ho. Alloy sample ke liye ek saaf stainless-steel ka chammach (ya ₹1 ka sikka) lo.
Do chhote cups aadhe paani se bharo aur har ek mein ek chammach namak ghol do.
Nail ko ek cup mein aur chammach ya sikke ko doosre mein daalo, taaki har ek aadha paani mein ho.
Chaar din tak roz dono ko dekho aur note karo ki kahin jang hai ya nahi, paani ka colour kya hai, aur badlaav kahan se shuru hota hai.

Table 4.7Jang par nazar

Din	Iron nail	Alloy
Din 1
Din 2
Din 4

Tumhari entries apne aap save hoti hain.

Ek-do din mein nail par orange-brown jang dikhne lagta hai, khaas kar water line ke paas, jabki stainless steel chamakta rehta hai. Lagbhag 18 % chromium, jo substitutional alloy ki tarah iron lattice mein baitha hai, surface par chromium oxide ki ek invisible, khud ko theek karne wali layer banata hai jo oxygen aur water ko iron se door rakhti hai. Alloying sirf hardness nahi, chemical behaviour bhi badalta hai.

4.4 Transition Elements ke Kuch Important Compounds

Do purple aur orange salts, potassium permanganate aur potassium dichromate, chemistry ke sabse useful oxidising agents mein se hain. Unse milne se pehle hume ek aur idea chahiye aur un oxides par ek nazar jinse yeh bante hain.

Definition

Disproportionation

Aisa redox reaction jismein ek hi species ek saath oxidise aur reduce hoti hai, aur ek product higher aur ek lower oxidation state mein milta hai.

Example $2 C u^{+}$ → $C u^{2 +}$ + $C u$

Example 4.9NCERT Example 4.9 · p. 105

Kya Cu⁺ water mein tikta hai?

$E^{\circ} (C u^{+} / C u) = + 0.52 V$ aur $E^{\circ} (C u^{2 +} / C u^{+}) = + 0.15 V$ diye hain; dikhao ki $C u^{+}$ water mein disproportionate hota hai aur $298 K$ par equilibrium constant estimate karo.

Pehle khud try karo. Phir solution ek-ek step karke kholo.

4.4.1 Metals ke Oxides aur Oxoanions

Zyadatar transition metals oxygen mein garam karne par dhundhle pad jaate hain ya jal jaate hain, aur kai metals kai oxides banate hain; unke highest oxides $M n_{2} O_{7}$ tak group number ke saath chalte hain, jaisa Section 4.3.7 ne dikhaya. Aisi series mein jo badalta hai woh hai oxide ka character. Manganese ke do oxides compare karo. $M n O$ ek green ionic solid hai jo acids mein ghulkar $M n^{2 +}$ salts deta hai, yaani basic oxide jaisa behaviour; scandium ko chhod kar pehli row ke har metal ka aisa ionic monoxide hota hai. $M n_{2} O_{7}$ ek dark, oily covalent liquid hai jo water ke saath react karke permanganic acid, $H M n O_{4}$ , deta hai, yaani non-metal oxide jaisa behaviour.

Farak metal par charge ka hai. Chhote charge wala metal ion ionic lattice mein aaraam se baithta hai, aur uske oxide ions $H^{+}$ pakadne ke liye free hote hain: oxide basic hai. +6 ya +7 wala metal centre oxygen ke electrons ko itni zor se apni taraf kheenchta hai ki bonds covalent ho jaate hain aur metal non-metal jaisa behave karta hai: oxide acidic hai. Beech mein oxides amphoteric hote hain. Chromium poori range dikhata hai: $C r O$ basic hai, $C r_{2} O_{3}$ amphoteric aur $C r O_{3}$ acidic, jo water ke saath chromic aur dichromic acids ( $H_{2} C r O_{4}$ , $H_{2} C r_{2} O_{7}$ ) deta hai. Vanadium teen steps mein yahi karta hai. $V_{2} O_{3}$ basic hai, aur $V_{2} O_{4}$ weakly basic, jo acids mein blue $V O^{2 +}$ ki tarah ghulta hai. $V_{2} O_{5}$ amphoteric hai lekin zyadatar acidic: alkalis ke saath vanadate ( $V O_{4}^{3 -}$ ) deta hai lekin acids ke saath $V O_{2}^{+}$ . Covalent bonding $C r O_{3}$ aur $V_{2} O_{5}$ jaise high oxides ke low melting points mein bhi dikhti hai.

Compare

Oxidation state ke saath oxide ka character badalta hai

Low state (+2)

$M n O$ , $C r O$ , $V O$
zyadatar ionic
basic: acids mein ghulte hain

Beech wali (+3, +4)

$C r_{2} O_{3}$ , $V_{2} O_{4}$ , $M n O_{2}$
kuch had tak covalent
amphoteric ya weakly basic

High (+5 se +7)

$V_{2} O_{5}$ , $C r O_{3}$ , $M n_{2} O_{7}$
covalent, kam melting point
acidic: oxoacids dete hain

Potassium dichromate

Potassium dichromate, $K_{2} C r_{2} O_{7}$ , laboratory mein chromium(VI) ka sabse pasandeeda salt hai. Yeh chamda tan karne mein use hone wale chromium salts ka starting material hai (Kanpur aur Chennai ke aas-paas ek bada industry) aur dyes aur doosre organic compounds banane mein oxidant hai. Yeh volumetric analysis mein primary standard bhi hai, kyunki iske crystals pure aur stable hote hain aur hawa se paani absorb nahi karte. Sodium salt water mein kahin zyada ghulta hai aur organic chemistry mein oxidant ke roop mein use hota hai.

Step by step

Chromite ore se potassium dichromate tak

Step 1 / 3

Ore ko roast karo

Powdered chromite, $F e C r_{2} O_{4}$ , ko achhi hawa ki supply mein sodium carbonate ke saath garam kiya jaata hai. Oxygen chromium ko +3 se +6 tak le jaata hai, jisse soluble yellow sodium chromate banta hai, jabki iron insoluble $F e_{2} O_{3}$ ban jaata hai. (Equation 4.6)

1 / 3

roasting

\begin{aligned} 4 F e C r_{2} O_{4} \\ + 8 N a_{2} C O_{3} \\ + 7 O_{2} \\ \overset{}{\to} 8 N a_{2} C r O_{4} \\ + 2 F e_{2} O_{3} \\ + 8 C O_{2} \end{aligned}

(4.6)

acidify karna

\begin{aligned} 2 N a_{2} C r O_{4} \\ + 2 H^{+} \\ \overset{}{\to} N a_{2} C r_{2} O_{7} \\ + 2 N a^{+} + H_{2} O \end{aligned}

(4.7)

cation badalna

\begin{aligned} N a_{2} C r_{2} O_{7} \\ + 2 K C l \\ \overset{}{\to} K_{2} C r_{2} O_{7} \\ + 2 N a C l \end{aligned}

(4.8)

Yellow chromate solution mein acid daalo to woh orange ho jaata hai; alkali daalo to yellow wapas aa jaata hai (Fig. 4.13). Koi electrons idhar-udhar nahi hote: dono ions mein chromium +6 hai, aur yeh switch ek acid–base reaction hai jismein do chromate ions ek shared oxygen se jud jaate hain.

yellow ⇌ orange

\begin{aligned} 2 C r O_{4}^{2 -} + 2 H^{+} \\ \overset{}{⇌} C r_{2} O_{7}^{2 -} \\ + H_{2} O \end{aligned}

(4.9)

3/3 $C r_{2} O_{7}^{2 -}$ : ek corner share karte do tetrahedra, jinka Cr–O–Cr angle lagbhag 126° hai.

Fig. 4.13Acid do chromate tetrahedra ko ek oxygen se jodta hai; alkali unhe phir alag kar deta hai.NCERT p. 106

Pehle step mein do alag chromate ions bane hain, har ek mein chromium atom tetrahedron ke corners par chaar oxygen atoms se bonded hai, aur tetrahedron ke edges dashed hain; har ek par CrO4 2 minus, alkali: yellow likha hai. Doosre step mein dono units khisak kar ek oxygen par mil jaate hain; right wale unit ka extra oxygen upar tair kar fade ho jaata hai, jis par H2O nikla likha hai, aur naye ion par Cr2O7 2 minus, acid daalne par orange likha hai. Aakhri step mein shared oxygen par ek arc 126 degrees mark karta hai aur label par likha hai shared corner O: do tetrahedra, ek shared oxygen.

Sodium aur potassium dichromate dono acid solution mein strong oxidising agents hain, jahan orange dichromate reduce hokar green $C r^{3 +}$ banta hai:

$E^\circ = +1.33\unit{V}$

\begin{aligned} C r_{2} O_{7}^{2 -} + 14 H^{+} \\ + 6 e^{-} \\ \overset{}{\to} 2 C r^{3 +} \\ + 7 H_{2} O \end{aligned}

(4.10)

Kisi bhi reaction ki poori equation likhne ke liye reductant ki half-equation lo, use itne se multiply karo ki woh chhe electrons chhode, (4.10) mein jodo aur jo dono sides par aaye use cancel karo. Iron(II) har ion par ek electron deta hai, isliye chhe chahiye; iodide, hydrogen sulphide aur tin(II) har formula unit par do dete hain, isliye teen chahiye. Jaise iron(II) ke saath:

\begin{aligned} C r_{2} O_{7}^{2 -} + 14 H^{+} \\ + 6 F e^{2 +} \\ \overset{}{\to} 2 C r^{3 +} \\ + 6 F e^{3 +} \\ + 7 H_{2} O \end{aligned}

(4.11)

Neeche ka redox combiner kai reductants ke liye yeh hisaab-kitaab karta hai. Ek oxidant aur ek reductant chuno, aur yeh half-equations ko scale karke jodta hai, check karta hai ki atoms aur charges balance hain, aur $E^{\circ}$ values se batata hai ki reaction hona chahiye ya nahi.

InteractiveRedox combiner

Buttons ke do groups. Pehla oxidising agent chunta hai: acidified dichromate ya acidified permanganate. Doosra reducing agent chunta hai: iron(II), iodide, hydrogen sulphide, tin(II), oxalate, sulphite, nitrite, hydrogen peroxide, ethanol ya chloride. Panel dono half-equations unke electrons ke saath, electrons match karne ke liye zaroori multipliers, aur hydrogen ions aur water cancel karne ke baad balanced overall ionic equation dikhata hai. Ek check line confirm karti hai ki har element aur total charge balance hai. Aakhri line do electrode potentials se standard cell potential deti hai aur batati hai ki standard conditions mein reaction feasible hai ya nahi; chloride ke saath dichromate feasible nahi hai lekin permanganate hai.

Fig. 4.14Acid mein dichromate ya permanganate aur ek reducing agent chuno; half-equations electrons ke hisaab se match karke jodi jaati hain.

Example

Breath test

Purani breath-alcohol tubes mein silica gel par acidified potassium dichromate hota hai. Saans ka ethanol crystals ko orange se green kar deta hai, jabki khud oxidise hokar ethanoic acid ban jaata hai. Balanced ionic equation likho aur pata karo ki ek mole ethanol ke saath kitne moles dichromate react karte hain.

Pehle khud try karo. Phir solution ek-ek step karke kholo.

Potassium permanganate

Potassium permanganate, $K M n O_{4}$ , pyrolusite, yaani mineral manganese dioxide, se banta hai. Raasta green potassium manganate se hokar jaata hai, jismein manganese +6 hai.

Step by step

Pyrolusite se potassium permanganate tak

Step 1 / 3

Alkaline fusion

$M n O_{2}$ ko potassium hydroxide aur ek oxidising agent, hawa ya $K N O_{3}$ , ke saath fuse kiya jaata hai. Manganese +4 se +6 par jaata hai aur melt $K_{2} M n O_{4}$ ki wajah se dark green ho jaata hai. (Equation 4.12)

1 / 3

\begin{aligned} 2 M n O_{2} + 4 K O H \\ + O_{2} \\ \overset{}{\to} 2 K_{2} M n O_{4} \\ + 2 H_{2} O \end{aligned}

(4.12)

\begin{aligned} 3 M n O_{4}^{2 -} + 4 H^{+} \\ \overset{}{\to} 2 M n O_{4}^{-} \\ + M n O_{2} \\ + 2 H_{2} O \end{aligned}

(4.13)

\begin{aligned} 2 M n^{2 +} \\ + 5 S_{2} O_{8}^{2 -} \\ + 8 H_{2} O \\ \overset{}{\to} 2 M n O_{4}^{-} \\ + 10 S O_{4}^{2 -} \\ + 16 H^{+} \end{aligned}

(4.14)

Potassium permanganate ke purple crystals itne gehre hote hain ki lagbhag kaale dikhte hain. Yeh sirf moderately soluble hai, room temperature par 100 g water mein lagbhag 6 se 7 g. Lekin iska colour itna tez hai ki ek crystal poori baalti ke paani ko rang deta hai. Lagbhag $513 K$ se upar garam karne par solid oxygen chhodta hai aur manganate aur manganese dioxide bachte hain:

\begin{aligned} 2 K M n O_{4} \\ \overset{}{\to} K_{2} M n O_{4} \\ + M n O_{2} + O_{2} \end{aligned}

(4.15)

Manganate aur permanganate dono mein chaar oxygen atoms manganese ke around tetrahedron ke corners par baithe hain. Mn–O bonds mein oxygen p orbitals aur manganese d orbitals ke overlap se π bonding bhi hai. (Solid $K M n O_{4}$ ka crystal structure bhi potassium perchlorate jaisa hai, jiska $C l O_{4}^{-}$ ion bhi tetrahedral hai.) d-electron count magnetism tay karta hai. Green manganate (Mn +6, $d^{1}$ ) mein ek unpaired electron hai aur yeh paramagnetic hai. Permanganate (Mn +7, $d^{0}$ ) mein koi nahi hai aur yeh diamagnetic hai, bas ek kamzor paramagnetism ko chhod kar jo temperature ke saath badalta hai. Isse ek paheli bachti hai. $d^{0}$ ion d–d colour nahi dikha sakta, phir bhi permanganate gehra purple aur dichromate orange hai. Inka colour ek alag process, charge transfer, se aata hai, jismein light ek electron ko oxygen se metal par le jaati hai. Ise, aur kamzor paramagnetism ko, samjhane ke liye molecular orbital theory chahiye, jo tum aage ke courses mein padhoge.

Permanganate kya banega, yeh solution ki acidity par depend karta hai (Fig. 4.15). Teen half-equations, unke electrode potentials ke saath, dikhati hain ki $H^{+}$ concentration result ko kitni zor se mod deta hai:

acid

\begin{aligned} M n O_{4}^{-} + 8 H^{+} \\ + 5 e^{-} \\ \overset{}{\to} M n^{2 +} \\ + 4 H_{2} O \\ E^{\circ} = + 1.51 V \end{aligned}

(4.16)

MnO₂ ki taraf

\begin{aligned} M n O_{4}^{-} + 4 H^{+} \\ + 3 e^{-} \\ \overset{}{\to} M n O_{2} \\ + 2 H_{2} O \\ E^{\circ} = + 1.69 V \end{aligned}

(4.17)

strong alkali

\begin{aligned} M n O_{4}^{-} + e^{-} \\ \overset{}{\to} M n O_{4}^{2 -} \\ E^{\circ} = + 0.56 V \end{aligned}

(4.18)

4/4Strongly alkaline solution mein yeh sirf ek leta hai, aur green manganate banta hai.

Fig. 4.15Ek oxidant, teen products: medium ke hisaab se permanganate 5, 3 ya 1 electrons leta hai.NCERT p. 107

Left mein ek permanganate ion hai, chaar oxygens ke saath manganese, jis par +7, purple likha hai. Doosre step mein acid aur plus 5 electrons likha ek arrow Mn2+ tak jaata hai, jis par +2, pale pink likha hai. Teesre step mein neutral aur plus 3 electrons likha doosra arrow MnO2 tak jaata hai, jis par +4, brown solid likha hai. Aakhri step mein strong alkali aur plus 1 electron likha teesra arrow MnO4 2 minus tak jaata hai, jis par +6, green likha hai.

Electrode potentials batate hain ki kya ho sakta hai, yeh nahi ki kitni jaldi. $E^{\circ} = + 1.51 V$ ke saath, jo $O_{2} / H_{2} O$ couple ke $+ 1.23 V$ se kaafi upar hai, acidified permanganate ko aas-paas ke water ko oxidise karke oxygen chhodni chahiye. Phir bhi laboratory mein iski bottle hafton chalti hai: reaction sirf garam solution mein ya tab dikhta hai jab use catalyse karne ke liye kuch $M n^{2 +}$ maujood ho. Oxalate titrations dono tareeke use karti hain. Permanganate ki pehli boondein dheere-dheere colour khoti hain, isliye flask ko lagbhag $333 K$ tak garam kiya jaata hai; thoda $M n^{2 +}$ ban jaane ke baad har boond turant decolourise ho jaati hai.

Permanganate reducing agents ki ek lambi list ko oxidise karta hai, aur medium tay karta hai ki khud manganese kitna reduce hoga. Table 4.8, Equation 4.21 ke baad, un reactions ko jama karta hai jo tumhe sabse zyada milenge. Koi bhi equation likhne ke liye us medium ki permanganate half-equation lo aur reductant ki half-equation utni baar lo jitni electrons cancel karne ke liye chahiye, phir jodo. Acid mein do examples:

iron(II)

\begin{aligned} M n O_{4}^{-} + 8 H^{+} \\ + 5 F e^{2 +} \\ \overset{}{\to} M n^{2 +} \\ + 5 F e^{3 +} \\ + 4 H_{2} O \end{aligned}

(4.19)

oxalate, garam

\begin{aligned} 2 M n O_{4}^{-} + 16 H^{+} \\ + 5 C_{2} O_{4}^{2 -} \\ \overset{}{\to} 2 M n^{2 +} \\ + 10 C O_{2} \\ + 8 H_{2} O \end{aligned}

(4.20)

Neutral ya halke alkaline solution mein, jahan manganese $M n O_{2}$ par ruk jaata hai, kuch reductants acid se zyada aage tak oxidise hote hain. Iodide classic case hai: iodine par rukne ke bajaye yeh seedha iodate tak jaata hai.

neutral

\begin{aligned} 2 M n O_{4}^{-} + I^{-} \\ + H_{2} O \\ \overset{}{\to} 2 M n O_{2} \\ + I O_{3}^{-} \\ + 2 O H^{-} \end{aligned}

(4.21)

Table 4.8Common reducing agents ke saath permanganate kya karta hai (acid mein Mn aakhir mein

M n^{2 +}

banta hai, neutral solution mein

M n O_{2}

)NCERT p. 107

Reducing agent	Medium	Kis mein oxidise hota hai
$F e^{2 +}$ (halka green)	acid	$F e^{3 +}$ (yellow)
$I^{-}$	acid	$I_{2}$
$C_{2} O_{4}^{2 -}$	acid, garam	$C O_{2}$
$H_{2} S$	acid	sulphur (ek halka yellow solid)
$S O_{3}^{2 -}$	acid	$S O_{4}^{2 -}$
$N O_{2}^{-}$	acid	$N O_{3}^{-}$
$I^{-}$	neutral	$I O_{3}^{-}$
$S_{2} O_{3}^{2 -}$	neutral	$S O_{4}^{2 -}$
$M n^{2 +}$	neutral	$M n O_{2}$

Titrations ke liye isse do practical baatein nikalti hain. Permanganate ko dilute sulphuric acid se acidify kiya jaata hai, hydrochloric acid se kabhi nahi, kyunki yeh chloride ko bhi chlorine mein oxidise kar dega (Example 4.5) aur titre zyada aayega. Aur kisi indicator ki zaroorat nahi: excess ki pehli boond ek halka, tikne wala pink chhod deti hai. Laboratory ke bahar bhi yahi oxidising power kai kaam aati hai. Dilute solutions, jo India mein lal dawa ke naam se bikte hain, kuon ko disinfect karte hain aur phal-sabziyan dhone mein kaam aate hain. Industry permanganate se textile fibres bleach karti hai aur oils ka colour nikaalti hai, aur organic chemists alkenes, alcohols aur benzene rings ki side chains ko oxidise karne ke liye is par bharosa karte hain.

Example

Tablet mein kitna iron hai?

Ek iron supplement tablet ko dilute sulphuric acid mein ghol kar $100.0 m L$ banaya jaata hai. Iske $25.0 m L$ hisse ko halka permanent pink tak pahunchne ke liye $0.00500 M$ $K M n O_{4}$ ka $10.8 m L$ lagta hai. Poore tablet mein iron(II) ka mass nikaalo ( $M_{Fe} = 55.85 g m o l^{- 1}$ ).

Pehle khud try karo. Phir solution ek-ek step karke kholo.

Try karke dekho

Permanganate ka colour udao

Tumhe chahiye

potassium permanganate ke kuch crystals (chemist ki dukaan par disinfectant ke roop mein milte hain)
paani ke do saaf glass
ek vitamin C tablet, ya aadhe nimbu ka ras
ek chammach aur ek jodi gloves

Pehle guess karo

Kuchli hui vitamin C milaate hue purple colour ka kya hoga?

Yeh halka pad jaayega, kyunki vitamin C permanganate ko reduce karta hai.Yeh gehra green ho jaayega.Yeh aur gehra purple ho jaayega.Kuch nahi badlega.

Ek glass paani mein potassium permanganate ke do-teen crystals gholo. Agar colour bahut gehra ho, to use itna dilute karo ki saaf, halka purple ho jaaye.
Aadha doosre glass mein daalo aur comparison ke liye alag rakh do.
Vitamin C tablet ko kuchlo. Pehle glass mein ek chutki daalo, hilao aur ek minute ruko. Phir ek-ek chutki karke aur daalo.
Har baar daalne ke baad colour note karo, doosre glass se compare karte hue.

Table 4.9Maine kya dekha

Glass	Colour	Dhundhla?
Bina chhue
Thoda vitamin C
Zyada vitamin C

Tumhari entries apne aap save hoti hain.

Purple halka padta jaata hai, kabhi-kabhi ek bhoore stage se hokar, jab tak liquid lagbhag colourless na ho jaaye, jabki bina chhua glass purple rehta hai. Ascorbic acid electrons deta hai aur manganese(VII) reduce hota hai: jahan solution kaafi acidic hai wahan lagbhag colourless $M n^{2 +}$ mein, aur jahan nahi hai wahan brown $M n O_{2}$ mein, jo liquid ko dhundhla kar deta hai. Yahi permanganate titration ki chemistry hai: colour khud batata hai ki saara reducing agent kab khatam hua.

Quick check

4 mein se 1

Potassium dichromate ke orange solution mein boond-boond sodium hydroxide daala jaata hai. Tumhe kya dikhta hai?

C r^{3 +}

banne se yeh green ho jaata hai.Chromate banne se yeh yellow ho jaata hai; chromium +6 hi rehta hai.Yeh purple ho jaata hai.Yeh orange hi rehta hai: pH ka koi asar nahi.

Answer dekho

Answer (B) Chromate banne se yeh yellow ho jaata hai; chromium +6 hi rehta hai.

pH badhane se (4.9) ulta ho jaata hai: dichromate toot kar yellow chromate ban jaata hai. Yeh acid–base change hai, reduction nahi, isliye green

C r^{3 +}

nahi aata.

4.5 Lanthanoids

Main table ke neeche chaudah-chaudah elements ki do rows hain. Pehli lanthanum ke baad aati hai (cerium se lutetium) aur 4f subshell bharti hai; doosri actinium ke baad aati hai (thorium se lawrencium) aur 5f bharti hai. Lanthanum aur actinium apne baad wale elements se itne milte-julte hain ki unhe hamesha unke saath hi discuss kiya jaata hai, aur chemists lanthanum ya kisi bhi lanthanoid ke liye symbol Ln use karte hain.

Dono rows bahut alag behave karti hain. Lagbhag har lanthanoid compound mein $L n^{3 +}$ ion hota hai, isliye row mein aage badhne par us ion ke size ke alawa bahut kam badalta hai, har step par thoda sa. Agar tum pata karna chaho ki sirf size chemistry par kaise asar daalta hai, to isse behtar elements ka set mushkil se milega, aur yeh kisi bhi d-series ke members se zyada ek jaise hain. Actinoids itne saaf-suthre nahi hain: ek element se agle tak woh bonding mein alag-alag sankhya ke electrons use karte hain, aur sab radioactive hain, jisse unhe study karna mushkil hai. Hum lanthanoids se shuru karte hain.

Table 4.10Lanthanum aur lanthanoids: xenon core ke bahar configurations, aur

r

, yaani

L n^{3 +}

ion ka radiusNCERT Table 4.9 · p. 110

Ln (Z)	Atom	$L n^{3 +}$	$r$ / pm
La (57)	$5 d^{1} 6 s^{2}$	$4 f^{0}$	103
Ce (58)	$4 f^{1} 5 d^{1} 6 s^{2}$	$4 f^{1}$	101
Pr (59)	$4 f^{3} 6 s^{2}$	$4 f^{2}$	99
Nd (60)	$4 f^{4} 6 s^{2}$	$4 f^{3}$	98
Pm (61)	$4 f^{5} 6 s^{2}$	$4 f^{4}$	97
Sm (62)	$4 f^{6} 6 s^{2}$	$4 f^{5}$	96
Eu (63)	$4 f^{7} 6 s^{2}$	$4 f^{6}$	95
Gd (64)	$4 f^{7} 5 d^{1} 6 s^{2}$	$4 f^{7}$	94
Tb (65)	$4 f^{9} 6 s^{2}$	$4 f^{8}$	92
Dy (66)	$4 f^{10} 6 s^{2}$	$4 f^{9}$	91
Ho (67)	$4 f^{11} 6 s^{2}$	$4 f^{10}$	90
Er (68)	$4 f^{12} 6 s^{2}$	$4 f^{11}$	89
Tm (69)	$4 f^{13} 6 s^{2}$	$4 f^{12}$	88
Yb (70)	$4 f^{14} 6 s^{2}$	$4 f^{13}$	87
Lu (71)	$4 f^{14} 5 d^{1} 6 s^{2}$	$4 f^{14}$	86

Aakhri column ke radii six-coordinate ions ke hain, nearest picometre tak rounded; doosre coordination numbers par based tables thodi alag values deti hain, lekin trend same rehta hai.

4.5.1 Electronic Configurations

Har lanthanoid atom ke bahar $6 s^{2}$ hota hai. Uske neeche 4f subshell cerium se lutetium tak bharta hai, lekin poori tarah regular nahi. Lanthanum, cerium, gadolinium aur lutetium ek electron 5d mein daalte hain, aur apne 4f sets khaali, lagbhag khaali, half-filled ( $4 f^{7}$ ) ya full ( $4 f^{14}$ ) rakhte hain. Tripositive ions kahin zyada saaf hain. Har lanthanoid $L n^{3 +}$ banata hai, aur us state mein series $4 f^{0}$ (La) se $4 f^{14}$ (Lu) tak chalti hai, har element par ek 4f electron zyada.

4.5.2 Atomic aur Ionic Sizes

Lanthanum se lutetium tak atoms aur ions lagaatar chhote hote hain: $L n^{3 +}$ radius lagbhag $103$ se $86 p m$ tak girta hai (Fig. 4.16). Ionic radii smoothly girti hain; metallic radii kam regularly girti hain, kyunki europium aur ytterbium metallic bonding ke liye sirf do electrons use karte hain aur isliye unke atoms kaafi bade hain.

Definition

Lanthanoid contraction

4f series, La se Lu, mein atoms aur ions ka dheere-dheere chhota hona, kyunki 4f electrons badhte nuclear charge ko bahut kamzor screen karte hain.

Example $L a^{3 +}$ lagbhag $103 p m$ , $L u^{3 +}$ lagbhag $86 p m$ .

3/3Kul milaakar, $L a^{3 +}$ se $L u^{3 +}$ tak radius lagbhag 17 pm sikudta hai.

Fig. 4.16Series mein

L n^{3 +}

ions ka radius lagbhag 17 pm girta hai (vertical axis 80 pm se shuru hoti hai).NCERT Fig. 4.6 · p. 109

Ek bar chart jiske neeche lanthanum se lutetium tak pandrah elements aur side mein picometres mein ionic radius hai; axis 80 picometres se shuru hoti hai. Pehle step mein lanthanum se gadolinium tak ke bars dikhte hain, har ek pichhle se thoda chhota. Doosre step mein terbium se lutetium tak ke bars jud jaate hain, aur girawat jaari rehti hai. Aakhri step mein ek dashed arrow lanthanum bar ke top (103 likha) se lutetium bar ke top (86 likha) tak jaata hai, saath mein note hai ki lagbhag 17 picometres chhota.

Ions kyun sikudte hain? Series mein har step nucleus mein ek proton aur 4f subshell mein ek electron jodta hai. 4f electron ek phaile hue, kai lobes wale region mein faila hota hai aur doosre electrons ko extra proton se theek se screen nahi kar paata, d-series mein d electron se bhi kharab. Isliye har step par effective nuclear charge thoda badhta hai aur poora electron cloud andar kheench jaata hai.

Iske nateeje f-block se kahin aage tak jaate hain:

5d metals lagbhag apne upar wale 4d metals jitne hi bade hain (zirconium $160 p m$ , hafnium $159 p m$ ), isliye zirconium aur hafnium nature mein saath milte hain aur unhe alag karna bahut mushkil hai.
Lanthanoids khud size mein itne kam alag hain ki unhe alag karne mein dashakon ki dheeraj bhari mehnat lagi; ab ion exchange aur solvent extraction in chhote farakon ka fayda uthate hain.
Hydroxides $L n (O H)_{3}$ ka basic character lanthanum se lutetium tak ghatta hai, kyunki chhota ion apne hydroxide ions ko zyada covalently pakadta hai.

4.5.3 Oxidation States

Har lanthanoid $L n^{3 +}$ banata hai. Kuch +2 ya +4 ions bhi banate hain, aur aisa karke lagbhag hamesha khaali, half-filled ya full 4f set tak pahunchte hain. Kyunki +3 inki ghar wali state hai, yeh anokhe ions wapas usmein jaane ko utsuk rehte hain, jisse yeh useful oxidising ya reducing agents bante hain.

Table 4.11+3 state ke bahar ke lanthanoid ionsNCERT p. 109

Ion	f count	Behaviour
$C e^{4 +}$	$4 f^{0}$	strong oxidant ( $E^{\circ} \approx + 1.74 V$ ); yeh water par itna dheere attack karta hai ki cerium(IV) sulphate titrant ki tarah kaam aata hai
$T b^{4 +}$	$4 f^{7}$	oxidant, jaise $T b O_{2}$ aur $T b F_{4}$ mein
Pr, Nd, Dy (+4)	–	sirf kuch solids mein, jaise oxide $P r O_{2}$
$E u^{2 +}$	$4 f^{7}$	mild reductant ( $E^{\circ} (E u^{3 +} / E u^{2 +}) \approx - 0.35 V$ )
$Y b^{2 +}$	$4 f^{14}$	zyada strong reductant ( $E^{\circ} \approx - 1.05 V$ )
$S m^{2 +}$	$4 f^{6}$	bahut strong reductant ( $E^{\circ} \approx - 1.55 V$ )

Samarium ek useful chetavni hai. Iska +2 ion $4 f^{6}$ hai, koi special configuration nahi, phir bhi $S m^{2 +}$ exist karta hai (samarium(II) iodide, $S m I_{2}$ , organic synthesis mein use hone wala reducing agent hai): special stability ek guide hai, law nahi.

4.5.4 General Characteristics

Taaza kata lanthanoid metal naram aur silvery-white hota hai, lekin hawa se surface react karne par chamak jaldi fiki pad jaati hai. Yeh heat aur electricity achhe se conduct karte hain aur common metallic structures apnate hain. Row mein inki properties dheere-dheere badalti hain: lanthanum se lutetium tak hardness do guna se zyada ho jaati hai, aur melting points lagbhag $1190 K$ (La) se lagbhag $1930 K$ (Lu) tak chadhte hain. Exceptions europium aur ytterbium hain, kabhi-kabhi samarium aur thulium bhi. Inki densities aur melting points padosiyon se mel nahi khaate, kyunki yeh metallic bond ko sirf do-do electrons dete hain.

Glass-blowers apni aankhen neodymium wale glass ke goggles se bachate hain, jo garam glass ki yellow chamak ka ek patla band absorb karta hai. Yeh patlapan lanthanoid colours ki pehchaan hai. Kai $L n^{3 +}$ ions crystals aur solution mein coloured hote hain, kyunki ek electron 4f orbitals ke beech jump kar sakta hai; lekin 4f orbitals itne andar dabe hain ki ligands unhe mushkil se chhoo paate hain, isliye har ion chaude bands ke bajaye sharp lines mein absorb karta hai. Bina 4f electron ( $L a^{3 +}$ ) ya full set ( $L u^{3 +}$ ) ke aisa koi jump possible nahi, aur yeh ions colourless hote hain. Yahi count magnetism bhi tay karta hai: $f^{0}$ ions ( $L a^{3 +}$ , $C e^{4 +}$ ) aur $f^{14}$ ions ( $Y b^{2 +}$ , $L u^{3 +}$ ) ko chhod kar har lanthanoid ion paramagnetic hai.

+3 itna universal kyun hai? Pehle do electrons ki keemat lagbhag calcium jitni hai (lagbhag $600$ aur $1200 k J m o l^{- 1}$ ). Teesre ki keemat zyada hai, lekin chhota, triply charged ion crystal lattice ya water mein itni energy release karta hai ki keemat wasool ho jaati hai. Third ionisation enthalpy wahan sabse kam hai jahan electron khone se special f set bachta hai: lanthanum ( $4 f^{0}$ bachta hai), gadolinium ( $4 f^{7}$ ) aur lutetium ( $4 f^{14}$ ) par isme dip aata hai. Section 4.3.3 wali exchange energy phir kaam kar rahi hai, ab f subshell mein.

Saare lanthanoids reactive metals hain. Inki $E^{\circ} (L n^{3 +} / L n)$ values ek patle band mein hain, lagbhag $- 2.2$ se $- 2.4 V$ (europium, lagbhag $- 2.0 V$ par, alag hai), magnesium ke $- 2.37 V$ ke kareeb. Practice mein shuru ke members lagbhag calcium jitni tezi se react karte hain aur baad wale aluminium jaise. Table inke reactions ka saar deti hai. Oxides $L n_{2} O_{3}$ aur hydroxides $L n (O H)_{3}$ alkaline earth metals ke oxides-hydroxides ki tarah basic hain.

Table 4.12Lanthanoids ke reactionsNCERT Fig. 4.7 · p. 111

Kiske saath	Conditions	Product
oxygen	jalta hai	$L n_{2} O_{3}$
water	garam	$L n (O H)_{3}$ + $H_{2}$
dilute acids	room temperature	$L n^{3 +}$ salts + $H_{2}$
halogens	jalta hai	$L n X_{3}$
hydrogen	halka garam karna	hydrides
carbon	lagbhag 2773 K	$L n_{3} C$ , $L n_{2} C_{3}$ , $L n C_{2}$
nitrogen	garam karna	$L n N$
sulphur	garam karna	$L n_{2} S_{3}$

India mein Indian Rare Earths Limited coastal sands ke monazite se yeh elements nikaalti hai, aur yeh kai jagah kaam aate hain. Neodymium–iron–boron magnets electric motors, wind turbines aur earphones chalate hain. Single lanthanoid oxides se bane phosphors screens aur lamps mein chamakte hain, aur mixed lanthanoid oxides petroleum ko crack karke petrol banane mein madad karte hain. Lanthanoids alloy steels mein bhi milaaye jaate hain. Mischmetall lagbhag 95 % lanthanoid metals (zyadatar cerium aur lanthanum) aur lagbhag 5 % iron ka alloy hai. Yeh gas lighters ka 'flint' hai aur shells aur bullets ke magnesium alloys mein jaata hai.

4.6 Actinoids

Actinoids thorium ( $Z = 90$ ) se lawrencium ( $Z = 103$ ) tak chalte hain. Har ek radioactive hai. Thorium aur uranium ke isotopes itne lambe jeene wale hain ki woh Earth ke banne ke samay se bache hain; sabse bhaari actinoids kuch ghante ya usse kam tikte hain aur ek baar mein sirf kuch atoms, ya zyada se zyada nanograms, hi banaye gaye hain. Uranium ke aage sab kuch reactors ya accelerators mein artificially banaya jaata hai, isi wajah se unki kaafi chemistry abhi bhi samjhi ja rahi hai. Thorium India ke liye khaas important hai: desh ke paas monazite mein bade reserves hain, aur iske nuclear programme ka teesra stage thorium-232 se uranium-233 breed karne ke liye design kiya gaya hai.

4.6.1 Electronic Configurations

Har actinoid atom ke bahar $7 s^{2}$ hota hai, lekin uske neeche 5f aur 6d levels energy mein itne paas hain ki electrons 5f mein utne saaf tareeke se nahi baithte jitna lanthanoids mein 4f bharta hai. Thorium ( $6 d^{2} 7 s^{2}$ ) mein ek bhi 5f electron nahi hai, halaanki uske upar wale lanthanoid cerium mein 4f mein ek pehle se hai. Protactinium ( $5 f^{2} 6 d^{1} 7 s^{2}$ ) se aage 5f bharta hai, aur nobelium ( $5 f^{14} 7 s^{2}$ ) par poora hota hai. Special f counts phir details tay karte hain: curium $[R n] 5 f^{7} 6 d^{1} 7 s^{2}$ hai, jo agla electron 6d mein daal kar half-filled 5f set bachata hai, bilkul waise jaise gadolinium $5 d^{1}$ ke saath $4 f^{7}$ rakhta hai. Lawrencium ko aam taur par $[R n] 5 f^{14} 6 d^{1} 7 s^{2}$ likha jaata hai, halaanki experiments batate hain ki uska aakhri electron shayad asal mein 7p mein hai.

5f orbitals ki shapes 4f orbitals jaisi hi hain lekin woh utne andar dabe nahi hain. 4f electrons bhare hue 5s aur 5p shells ke andar, padosi atoms se chhupe rehte hain. 5f electrons zyada bahar tak phailte hain aur bonding mein hissa le sakte hain. Dono families ke zyadatar farak isi ek fact se nikalte hain.

4.6.2 Ionic Sizes

Actinoids mein actinoid contraction hota hai: unke atoms aur $M^{3 +}$ ions series mein sikudte hain, bilkul lanthanoids ki tarah. Ek element se agle tak sikudan lanthanoids se zyada hai, kyunki 5f electrons nuclear charge ko 4f electrons se bhi kamzor shield karte hain.

Definition

Actinoid contraction

Atomic number badhne ke saath actinoid atoms aur $M^{3 +}$ ions ka lagaatar chhota hona; ek element se agle tak ka step lanthanoid contraction se bada hai kyunki 5f electrons kamzor shield karte hain.

4.6.3 Oxidation States

Actinoid oxidation states plot karo (Fig. 4.17) to phir ek pahaadi dikhti hai, jaise 3d metals ke liye dikhi thi. Highest state thorium par +4 se protactinium par +5, uranium par +6, aur neptunium aur plutonium par +7 tak chadhti hai, phir girti hai. Curium se aage +3 hi rule hai, aur nobelium to +2 pasand karta hai, jisse uska $5 f^{14}$ set full rehta hai. Lagbhag sab +3 ions bhi bana sakte hain. Shuru ke actinoids itne vary isliye karte hain kyunki unke 5f, 6d aur 7s levels energy mein paas-paas hain, isliye bonding mein alag-alag sankhya ke electrons use ho sakte hain. Water mein +3 aur +4 states ke ions hydrolyse hone lagte hain, aur uranium(VI) aur plutonium(VI) linear oxocations $U O_{2}^{2 +}$ aur $P u O_{2}^{2 +}$ ki tarah dikhte hain.

3/3Curium se aage +3 haavi hai; Md aur No +2 ions bhi banate hain.

Fig. 4.17Shuru ke actinoids kai oxidation states dikhate hain; baad wale +3 par tik jaate hain (aur Md aur No ke liye +2).NCERT Table 4.11 · p. 112

Ek chart jiske neeche actinium se lawrencium tak pandrah elements aur side mein oxidation states +2 se +7 hain; ek shaded band +3 mark karta hai. Pehle step mein har element ka +3 par ek purple dot hai, jis par sab mein +3 likha hai (thorium sirf kabhi-kabhi). Doosre step mein blue dots shuru ke actinoids ki higher states jodte hain: thorium +4, protactinium +4 aur +5, uranium +4 se +6, neptunium aur plutonium +4 se +7, americium +4 se +6, aur label par kai states, early actinoids likha hai. Aakhri step mein curium aur berkelium ko +4 dots milte hain, aur mendelevium aur nobelium ke liye +2 par green rings jud jaate hain.

Akela uranium dikhata hai ki yeh chemistry kitni vividh hai: acid solution mein yeh laal-sa $U^{3 +}$ , green $U^{4 +}$ aur yellow $U O_{2}^{2 +}$ ke roop mein mil sakta hai, har ek ke apne reactions ke saath. Isliye actinoids, lanthanoids ke ulat, ek typical state se samjhaaye nahi ja sakte; khaas kar series ke pehle half mein har element ko alag se seekhna padta hai.

4.6.4 General Characteristics aur Lanthanoids se Comparison

Actinoid metals lanthanoids ki tarah silvery hain, lekin baaki baaton mein kam uniform. Inki metallic radii element se element lanthanoid radii ke mukable kahin zyada uchhalti hain, isliye yeh metals structures ki anokhi variety mein crystallise hote hain. Akele plutonium ki room temperature aur melting point ke beech chhe solid forms hain. Chemically yeh lanthanoids se bhi zyada reactive hain, sabse zyada fine powders ke roop mein, jo hawa mein aag pakad sakte hain. Kuch reagents ke saath yeh aise behave karte hain:

acids: hydrochloric acid sabko ghol deta hai, lekin nitric acid zyadatar ko mushkil se chhoota hai, kyunki yeh un par protective oxide film chadha deta hai;
water: ubalta paani inhe oxide aur hydride ke mixture mein badal deta hai;
non-metals: zyadatar kaafi moderate temperatures par inse jud jaate hain;
alkalis: koi reaction nahi.

Kam dabe 5f orbitals se do aur farak nikalte hain. Pehla, shuru ke actinoids shuru ke lanthanoids se zyada aasaani se electrons khote hain. Inki ionisation enthalpies sirf mote taur par pata hain, lekin saaf taur par kam hain. Series mein shuru mein juda 5f electron nucleus se 4f electron ke mukable door rehta hai, isliye uske aur nuclear charge ke beech zyada inner electrons hote hain. Woh kam mazbooti se pakda jaata hai aur bonding mein aasaani se use hota hai. Doosra, inka magnetism predict karna zyada mushkil hai. Magnetic susceptibility abhi bhi lagbhag unpaired 5f electrons ki ginti ke saath badhti-ghatti hai, jaise lanthanoids mein, lekin values aam taur par kam hain.

Compare

Lanthanoids aur actinoids aamne-saamne

Lanthanoids (4f)

outer $6 s^{2}$ ; 4f Ce se Lu tak bharta hai
lagaatar, smooth contraction
lagbhag sirf +3; kuch +2 ya +4
zyadatar non-radioactive (Pm ko chhod kar)
f orbitals andar dabe: f bonding bahut kam
ek doosre se bahut milte-julte

Actinoids (5f)

outer $7 s^{2}$ ; shuru mein 5f aur 6d mein muqabla
har element par bada contraction
pehle half mein kai states (+7 tak)
sab radioactive
5f orbitals kam dabe: bonding mein hissa lete hain
sirf doosre half mein lanthanoid jaise, halaanki padosi phir bhi ek doosre se milte hain

Lanthanoid contraction par itna dhyaan aur actinoid contraction par itna kam kyun? Dono apne baad wale elements ko sikodte hain. Lekin lanthanoids ke baad jaane-pehchaane 5d metals aate hain, hafnium se mercury, jinke size aur chemistry ko contraction badal deta hai. Actinoids ke baad wale elements ek baar mein sirf kuch atoms banaye gaye hain, isliye actinoid contraction ke paas samjhane ko bahut kam chemistry hai.

Example 4.10NCERT Example 4.10 · p. 113

Terbium +4 tak kyun pahunch sakta hai

Terbium ( $Z = 65$ ) $[X e] 4 f^{9} 6 s^{2}$ hai. +3 ke alawa yeh $T b O_{2}$ aur $T b F_{4}$ jaise terbium(IV) compounds banata hai. Samjhao, aur predict karo ki terbium(IV) oxidising agent ki tarah kaam karega ya reducing agent ki tarah.

Pehle khud try karo. Phir solution ek-ek step karke kholo.

4.7 d- aur f-Block Elements ke Kuch Applications

Kitchen mein chaaron taraf dekho, tumhe d- aur f-blocks kaam karte milenge: steel ka chaaku, stainless sink, deewar par white paint, torch ki battery aur phone speaker ka magnet. In saare materials mein steel sabse zyada matra mein banta hai, aur yeh construction ki reedh ki haddi hai. Steel plant blast furnace mein iron ore ko reduce karta hai aur extra carbon aur doosri impurities ko jala deta hai. Phir woh chahe gaye grade ke liye carbon ke saath chromium, manganese, nickel ya doosre metals naap kar milaata hai.

Kai compounds ka ek khaas kaam hota hai. Titanium dioxide, $T i O_{2}$ , paint, paper aur toothpaste ka chamakdaar white pigment hai. Manganese dioxide dry cells ke andar ka oxidant hai, aur zinc, nickel aur cadmium doosri batteries mein jaate hain; cobalt, nickel aur manganese ab lithium-ion cells ke cathodes bharte hain. Silver bromide, $A g B r$ , light mein kaala padta hai, jisse photographic film possible hui. Copper, silver aur gold ko aaj bhi 'coinage metals' kaha jaata hai. Lekin roz ke coins ab cupronickel ya stainless steel jaise saste alloys se bante hain, aur gold aur silver coins zyadatar collectors khareedte hain. Sabse badh kar, transition metals aur unke compounds chemical industry ke kuch sabse bade processes ko catalyse karte hain:

Table 4.13Transition metal catalysts use karne wale kuch industrial processesNCERT p. 114

Process	Catalyst	Badlaav
Contact process	$V_{2} O_{5}$	$S O_{2}$ se $S O_{3}$ (sulphuric acid ke liye)
Haber process	finely divided iron	nitrogen aur hydrogen se ammonia
Oils ka hydrogenation	nickel	liquid oils se solid fats
Ziegler–Natta	$T i C l_{4}$ aur $A l (C_{2} H_{5})_{3}$	ethene se polythene
Wacker process	$P d C l_{2}$	ethene se ethanal
Reppe synthesis	nickel complexes	ethyne se benzene aur doosri rings

f-block isme strong neodymium magnets, glass polish karne ke liye cerium-based powders, energy-saving lamps aur LED screens ke phosphors, aur nuclear fuels thorium aur uranium jodta hai.

Flash cards · 9

Kaun kya karta hai?

1 / 9

Quick check

2 mein se 1

Har catalyst ko uske industrial process se match karo.

Left mein koi item tap karo, phir right mein uska match.

Answer dekho

Answer

$V_{2} O_{5}$ : Contact process
iron : Haber process
nickel : oils ka hydrogenation
$P d C l_{2}$ : Wacker process

Vanadium(V) oxide

S O_{3}

banata hai, iron ammonia banata hai, nickel oils mein hydrogen jodta hai, aur palladium chloride ethene ko ethanal mein oxidise karta hai.

Recap

Summary aur key points

d-block (groups 3–12) chaar series mein $(n - 1) d$ orbitals bharta hai; f-block 4f (lanthanoids) aur 5f (actinoids) bharta hai (Section 4.1).
Transition element ke atom ya common ion mein adhoora d subshell hota hai; Zn, Cd aur Hg mein nahi (Section 4.2).
Outer configurations $(n - 1) d^{1 – 10} n s^{1 – 2}$ follow karti hain, Cr $3 d^{5} 4 s^{1}$ aur Cu $3 d^{10} 4 s^{1}$ jaise exceptions ke saath; ions pehle ns electrons khote hain (Section 4.2, Section 4.3.3).
Metallic bonding $(n - 1) d$ electrons use karti hai, jisse high melting points aur enthalpies of atomisation milti hain jo row ke beech mein peak karti hain (Section 4.3.1).
Row mein radii dheere-dheere ghatti hain; lanthanoid contraction 4d aur 5d members ko lagbhag same size ka bana deta hai (Section 4.3.2).
Ionisation enthalpies dheere badhti hain; $d^{5}$ aur $d^{10}$ par breaks exchange energy se aate hain (Section 4.3.3).
Oxidation states ek se alag hoti hain; maximum Mn (+7) tak 4s + 3d electrons ke barabar hota hai, phir girta hai (Section 4.3.4).
Electrode potentials atomisation, ionisation aur hydration ko dikhate hain; sirf copper ka $E^{\circ} (M^{2 +} / M)$ positive hai (Section 4.3.5, Section 4.3.6).
Oxygen aur fluorine highest states ko stabilise karte hain; oxygen behtar karta hai kyunki woh multiple bonds banata hai (Section 4.3.7).
Unpaired d electrons se paramagnetism ( $μ = \sqrt{n (n + 2)}$ BM) aur d–d transitions se colour aata hai (Section 4.3.9, Section 4.3.10).
Transition metals complexes banate hain, reactions catalyse karte hain, aur interstitial compounds aur alloys banate hain (Section 4.3.11, Section 4.3.12, Section 4.3.14).
$K_{2} C r_{2} O_{7}$ (chromite se) aur $K M n O_{4}$ (pyrolusite se) strong oxidants hain jinke products pH par depend karte hain (Potassium dichromate, Potassium permanganate).
Lanthanoids mainly +3 aur lagaatar contraction dikhate hain; actinoids radioactive hain, zyada states dikhate hain aur har element par zyada sikudte hain (Section 4.5, Section 4.6).
Steels, pigments, batteries, catalysts aur nuclear fuels in elements ke khaas uses hain (Section 4.7).

Apna NCERT exercise question dhoondo

Hamare practice questions ncert.ai ke liye likhe gaye hain aur NCERT exercises ko follow karte hain. Apni textbook ke question se match karne wala question dhoondo; uska answer uske saath hai.

Tumhari NCERT textbook mein	Yahan practice question
NCERT Exercises Q4.1	Practice Q1
NCERT Exercises Q4.2	Practice Q2
NCERT Exercises Q4.3	Practice Q3
NCERT Exercises Q4.4	Practice Q4
NCERT Exercises Q4.5	Practice Q5
NCERT Exercises Q4.6	Practice Q6
NCERT Exercises Q4.7	Practice Q7
NCERT Exercises Q4.8	Practice Q8
NCERT Exercises Q4.9	Practice Q9
NCERT Exercises Q4.10	Practice Q10
NCERT Exercises Q4.11	Practice Q11
NCERT Exercises Q4.12	Practice Q12
NCERT Exercises Q4.13	Practice Q13
NCERT Exercises Q4.14	Practice Q14
NCERT Exercises Q4.15	Practice Q15
NCERT Exercises Q4.16	Practice Q16
NCERT Exercises Q4.17	Practice Q17
NCERT Exercises Q4.18	Practice Q18
NCERT Exercises Q4.19	Practice Q19
NCERT Exercises Q4.20	Practice Q20
NCERT Exercises Q4.21	Practice Q21
NCERT Exercises Q4.22	Practice Q22
NCERT Exercises Q4.23	Practice Q23
NCERT Exercises Q4.24	Practice Q24
NCERT Exercises Q4.25	Practice Q25
NCERT Exercises Q4.26	Practice Q26
NCERT Exercises Q4.27	Practice Q27
NCERT Exercises Q4.28	Practice Q28
NCERT Exercises Q4.29	Practice Q29
NCERT Exercises Q4.30	Practice Q30
NCERT Exercises Q4.31	Practice Q31
NCERT Exercises Q4.32	Practice Q32
NCERT Exercises Q4.33	Practice Q33
NCERT Exercises Q4.34	Practice Q34
NCERT Exercises Q4.35	Practice Q35
NCERT Exercises Q4.36	Practice Q36
NCERT Exercises Q4.37	Practice Q37
NCERT Exercises Q4.38	Practice Q38

Quick check: MCQs

4.1 Periodic Table mein Position3 questions
4.2 d-Block Elements ki Electronic Configurations3 questions
4.3.1 Physical Properties3 questions
4.3.3 Ionisation Enthalpies3 questions
4.3.4 Oxidation States3 questions
4.3.6 $\ce{M^3+}/\ce{M^2+}$ Standard Electrode Potentials ke Trends3 questions
4.3.7 Higher Oxidation States ki Stability ke Trends3 questions
4.3.8 Chemical Reactivity aur $E^\circ$ Values2 questions
4.3.9 Magnetic Properties3 questions
4.3.10 Coloured Ions ka Banna3 questions
4.3.14 Alloy Formation4 questions
Potassium permanganate4 questions
4.5.4 General Characteristics4 questions
4.6.4 General Characteristics aur Lanthanoids se Comparison3 questions
4.7 d- aur f-Block Elements ke Kuch Applications2 questions

Glossary · 15

Key terms (English + Hindi)

actinoidऐक्टिनॉयडaiktinoid: Chaudah 5f elements mein se ek, thorium se lawrencium; sab radioactive hain.Chapter mein pehli baar yahan aaya →
actinoid contractionऐक्टिनॉयड आकुंचनaiktinoid aakunchan: Actinoids mein size ki kami, jo har element par lanthanoid contraction se zyada hai.Chapter mein pehli baar yahan aaya →
alloyमिश्रातुmishraatu: Ek metal ka doosre elements ke saath metallic mixture, jaise brass (Cu–Zn).Chapter mein pehli baar yahan aaya →

d–d transition: Visible light absorb karne par metal ion ke split d-orbital sets ke beech electron ka jump; zyadatar transition metal colours ki wajah yahi hai.Chapter mein pehli baar yahan aaya →
diamagneticप्रतिचुंबकीयpratichumbakiya: Magnetic field se halka sa repel hota hai; saare electrons paired.Chapter mein pehli baar yahan aaya →
disproportionationअसमानुपातनasamanupatan: Aisa reaction jismein ek hi species oxidise aur reduce dono hoti hai, jaise $2 C u^{+} \overset{}{\to} C u^{2 +} + C u$ .Chapter mein pehli baar yahan aaya →

enthalpy of atomisationपरमाणुकरण एन्थैल्पीparmanukaran enthalpy: Ek mole element ko alag-alag gaseous atoms mein badalne par enthalpy change.Chapter mein pehli baar yahan aaya →
exchange energyविनिमय ऊर्जाvinimay urja: Degenerate orbitals mein parallel spins wale electrons ko milne wali stabilisation, lagbhag aise pairs ki ginti ke proportional.Chapter mein pehli baar yahan aaya →

inner transition elementआंतर संक्रमण तत्वaantar sankraman tatva: f-block element, jismein 4f ya 5f subshell bhar raha hota hai.Chapter mein pehli baar yahan aaya →
interstitial compoundअंतराकाशी यौगिकantarakashi yaugik: Aisa compound jismein chhote atoms (H, B, C, N) metal lattice ke holes mein baithe hote hain, jaise $W C$ .Chapter mein pehli baar yahan aaya →

lanthanoidलैन्थेनॉयडlanthenoid: Chaudah 4f elements mein se ek, cerium se lutetium (lanthanum ko inke saath padha jaata hai).Chapter mein pehli baar yahan aaya →
lanthanoid contractionलैन्थेनॉयड आकुंचनlanthenoid aakunchan: La se Lu tak size mein lagaatar kami, jo 4f electrons ki kamzor shielding se hoti hai.Chapter mein pehli baar yahan aaya →

paramagneticअनुचुंबकीयanuchumbakiya: Unpaired electrons ki wajah se magnetic field ke andar kheencha jaata hai.Chapter mein pehli baar yahan aaya →

spin-only magnetic momentकेवल प्रचक्रण चुंबकीय आघूर्णkeval prachakran chumbakiya aaghurn: $μ = \sqrt{n (n + 2)}$ BM, sirf $n$ unpaired electrons ke spins se aane wala moment.Chapter mein pehli baar yahan aaya →

transition elementसंक्रमण तत्वsankraman tatva: Aisa element jiske atom ya common ion mein adhoora d subshell ho; yaani group 12 ko chhod kar d-block.Chapter mein pehli baar yahan aaya →

The d- and f-Block Elements: Class 12 Chemistry Chapter 4 Hinglish mein

Is chapter mein aap kya seekhenge

4.1 Periodic Table mein Position

4.2 d-Block Elements ki Electronic Configurations

4.3 Transition Elements (d-Block) ki General Properties

4.3.1 Physical Properties

4.3.2 Transition Metals ke Atomic aur Ionic Sizes mein Variation

4.3.3 Ionisation Enthalpies

4.3.4 Oxidation States

4.3.5 $M^{2 +} / M$ Standard Electrode Potentials ke Trends

4.3.6 $M^{3 +} / M^{2 +}$ Standard Electrode Potentials ke Trends

4.3.7 Higher Oxidation States ki Stability ke Trends

4.3.8 Chemical Reactivity aur $E^{\circ}$ Values

4.3.9 Magnetic Properties

4.3.10 Coloured Ions ka Banna

4.3.11 Complex Compounds ka Banna

4.3.12 Catalytic Properties

4.3.13 Interstitial Compounds ka Banna

4.3.14 Alloy Formation

4.4 Transition Elements ke Kuch Important Compounds

4.4.1 Metals ke Oxides aur Oxoanions

Potassium dichromate

Potassium permanganate

4.5 Lanthanoids

4.5.1 Electronic Configurations

4.5.2 Atomic aur Ionic Sizes

4.5.3 Oxidation States

4.5.4 General Characteristics

4.6 Actinoids

4.6.1 Electronic Configurations

4.6.2 Ionic Sizes

4.6.3 Oxidation States

4.6.4 General Characteristics aur Lanthanoids se Comparison

4.7 d- aur f-Block Elements ke Kuch Applications

Summary aur key points

Practice questions answers ke saath (NCERT “Exercises”)

Apna NCERT exercise question dhoondo

Quick check: MCQs

Key terms (English + Hindi)

Tum chapter ke end tak pahunch gaye

4.1 Periodic Table mein Position

4.2 d-Block Elements ki Electronic Configurations

4.3 Transition Elements (d-Block) ki General Properties

4.3.1 Physical Properties

4.3.2 Transition Metals ke Atomic aur Ionic Sizes mein Variation

4.3.3 Ionisation Enthalpies

4.3.4 Oxidation States

4.3.5 MX2+/M Standard Electrode Potentials ke Trends

4.3.6 MX3+/MX2+ Standard Electrode Potentials ke Trends

4.3.7 Higher Oxidation States ki Stability ke Trends

4.3.8 Chemical Reactivity aur E∘ Values

4.3.9 Magnetic Properties

4.3.10 Coloured Ions ka Banna

4.3.11 Complex Compounds ka Banna

4.3.12 Catalytic Properties

4.3.13 Interstitial Compounds ka Banna

4.3.14 Alloy Formation

4.4 Transition Elements ke Kuch Important Compounds

4.4.1 Metals ke Oxides aur Oxoanions

Potassium dichromate

Potassium permanganate

4.5 Lanthanoids

4.5.1 Electronic Configurations

4.5.2 Atomic aur Ionic Sizes

4.5.3 Oxidation States

4.5.4 General Characteristics

4.6 Actinoids

4.6.1 Electronic Configurations

4.6.2 Ionic Sizes

4.6.3 Oxidation States

4.6.4 General Characteristics aur Lanthanoids se Comparison

4.7 d- aur f-Block Elements ke Kuch Applications

Apna NCERT exercise question dhoondo

Quick check: MCQs

Tum chapter ke end tak pahunch gaye

4.3.5 $M^{2 +} / M$ Standard Electrode Potentials ke Trends

4.3.6 $M^{3 +} / M^{2 +}$ Standard Electrode Potentials ke Trends

4.3.8 Chemical Reactivity aur $E^{\circ}$ Values