JEE Mains Chemistry · Teaching notes

The d- and f-Block Elements — JEE Mains Chemistry

The d- and f-Block Elements has 214 past-year questions from 2021 to 2026, and 46 of them ask for a number rather than an option. About half of those numbers are a spin-only magnetic moment: find the ion a clue points to, count its unpaired d or f electrons, and use √(n(n+2)) BM. The rest is recall with a few rules behind it: ions lose their s electrons first, a higher oxidation state makes an oxide more acidic and an ion a stronger oxidant, and the medium decides what permanganate and dichromate turn into. The cation tests of salt analysis are here too, because most of them are d-block chemistry.

Every subtopic, worked example, formula and trap in one printable document — answers shown, ready to share.

All 214 past questions JEE Mains Chemistry strategy JEE Mains home

Subtopic notes

Formula & revision sheet

8 formulas · 13 reference tables · 42 gotchas across all subtopics — the exam-eve cheat-sheet

Electronic Configuration and General Properties

Formulas (1)

Configurations of d-block atoms and ions · d electrons in a 3d ion $n_d(\mathrm{M^{n+}}) = Z - 18 - n \qquad (n \ge 2)$

Reference tables (2)

Ionisation enthalpies across the 3d series10 rows

Metal	First IE (kJ/mol)	Second IE (kJ/mol)	Third IE (kJ/mol)	What it shows
Sc	631	1235	2389	Sc³⁺ is d⁰, so +3 is easy and is its only state
Ti	656	1309	2652	A steady rise with the nuclear charge
V	650	1414	2828	A steady rise with the nuclear charge
Cr	653	1592	2987	Low first IE (lone 4s); high second IE (breaks 3d⁵) Highest second IE from Sc to Fe, but its third IE is below Mn's.
Mn	717	1509	3248	High third IE: Mn²⁺ is 3d⁵
Fe	762	1561	2957	Low third IE: Fe²⁺ loses one electron to reach 3d⁵
Co	758	1644	3232	Rises again after the dip at Fe
Ni	736	1752	3393	Rises again after the dip at Fe
Cu	745	1958	3554	Highest second IE of the series: Cu⁺ is 3d¹⁰
Zn	906	1734	3833	Highest first IE: a filled 4s² over a filled 3d¹⁰

Values rounded to the nearest kJ/mol. The kinks, not the exact numbers, decide the questions.

Melting points, atomisation, density, catalysts and interstitial compounds10 rows

Metal	Atomisation enthalpy (kJ/mol)	Metallic radius (pm)	Density (g/cm³)	Point tested
Sc	326	164	2.99	Largest atom of the series
Ti	473	147	4.51	Ti⁴⁺ in TiCl₄ is d⁰: the Ziegler–Natta catalyst is diamagnetic
V	515	135	6.11	Highest atomisation enthalpy of the 3d series
Cr	397	129	7.19	Smallest radius among Sc, Ti, V, Cr, Mn and Zn
Mn	281	137	7.21	A dip: 3d⁵ holds its d electrons out of the bonding
Fe	416	126	7.87	Catalyst of the Haber process
Co	425	125	8.90	Dense, high-melting
Ni	430	125	8.91	Catalyst for hydrogenating oils
Cu	339	128	8.96	Densest of the listed 3d metals
Zn	126	137	7.14	Lowest atomisation enthalpy: soft, low-melting Zn, Cd and Hg have filled d subshells; they are the soft end of each series.

The atomisation enthalpy tracks the number of unpaired d electrons that join the metallic bond.

Watch out for (6)

Ions lose 4s before 3d
→ Configurations of d-block atoms and ions
The 4d series has more exceptions than the 3d
→ Configurations of d-block atoms and ions
Cr beats Mn on the second IE only
→ Ionisation enthalpies across the 3d series
Cr is not the highest second IE of the whole series
→ Ionisation enthalpies across the 3d series
A catalyst weakens bonds and uses 4s electrons too
→ Melting points, atomisation, density, catalysts and interstitial compounds
The group-7/group-8 order flips in the 5d series
→ Melting points, atomisation, density, catalysts and interstitial compounds

Oxidation States and Electrode Potentials

Formulas (1)

Why Cu²⁺ is the stable copper ion in water · Iodometry of copper(II) $\mathrm{2Cu^{2+} + 4I^{-} \rightarrow Cu_2I_2 + I_2} \qquad \mathrm{I_2 + 2S_2O_3^{2-} \rightarrow 2I^{-} + S_4O_6^{2-}}$

Reference tables (2)

Oxidation states of the 3d metals10 rows

Metal	Oxidation states	Most stable in water	Highest fluoride and oxide
Sc	+3	+3	$\mathrm{ScF_3}$ , $\mathrm{Sc_2O_3}$ The only 3d metal with a single oxidation state besides 0.
Ti	+2, +3, +4	+4	$\mathrm{TiF_4}$ , $\mathrm{TiO_2}$
V	+2, +3, +4, +5	+4 (as $\mathrm{VO^{2+}}$ ) and +5	$\mathrm{VF_5}$ , $\mathrm{V_2O_5}$
Cr	+2, +3, +4, +5, +6	+3	$\mathrm{CrF_6}$ , $\mathrm{CrO_3}$
Mn	+2, +3, +4, +5, +6, +7	+2	$\mathrm{MnF_4}$ , $\mathrm{Mn_2O_7}$ Highest oxide (+7) and highest fluoride (+4) differ by 3.
Fe	+2, +3 (+4 and +6 rare)	+3 in air, +2 without it	$\mathrm{FeF_3}$ , $\mathrm{Fe_2O_3}$
Co	+2, +3, +4	+2	$\mathrm{CoF_3}$ , $\mathrm{Co_3O_4}$
Ni	+2, +3, +4	+2	$\mathrm{NiF_2}$ , NiO
Cu	+1, +2	+2	$\mathrm{CuF_2}$ , CuO
Zn	+2	+2	$\mathrm{ZnF_2}$ , ZnO

The number of states peaks at Mn; the ends of the series (Sc, Zn) show one.

E° values: which ions reduce acid and which oxidise9 rows

Metal	E° of M²⁺/M (V)	E° of M³⁺/M²⁺ (V)	What it means
Ti	−1.63	−0.37	Ti²⁺ is a reductant and liberates hydrogen
V	−1.18	−0.26	V²⁺ is a reductant and liberates hydrogen
Cr	−0.90	−0.41	Cr²⁺ is a strong reductant: it becomes Cr³⁺, d³
Mn	−1.18	+1.57	Mn³⁺ is a strong oxidant: it becomes Mn²⁺, d⁵
Fe	−0.44	+0.77	Fe³⁺ is a mild oxidant; lower than Mn because Fe³⁺ is d⁵
Co	−0.28	+1.97	Co³⁺ is the strongest oxidant of the series in water
Ni	−0.25	No simple Ni³⁺ in water	Ni²⁺ is the stable ion
Cu	+0.34	No Cu³⁺ in water	The only positive M²⁺/M value: Cu gives no hydrogen with dilute acid Cu has the highest M²⁺/M value of the 3d series.
Zn	−0.76	No Zn³⁺ in water	Zn²⁺ (d¹⁰) is the only ion

Negative M³⁺/M²⁺: the 2+ ion reduces acid. Large positive M³⁺/M²⁺: the 3+ ion is a strong oxidant.

Watch out for (6)

The d-block trend runs the other way from the p-block
→ Oxidation states of the 3d metals
Scandium has no +4
→ Oxidation states of the 3d metals
Iron's M³⁺/M²⁺ value is not above manganese's
→ E° values: which ions reduce acid and which oxidise
Count the free ion unless a complex is named
→ E° values: which ions reduce acid and which oxidise
The hydration enthalpy of Cu²⁺ is larger, not smaller
→ Why Cu²⁺ is the stable copper ion in water
Cu₂I₂ and CuI are one compound
→ Why Cu²⁺ is the stable copper ion in water

Magnetic Moment and Colour

Formulas (1)

The spin-only magnetic moment · Spin-only magnetic moment $\mu = \sqrt{n(n+2)}\ \text{BM}$

Reference tables (1)

Colours of the aqueous 3d ions17 rows

Ion	d configuration	Unpaired electrons (free ion)	Colour in water
$\mathrm{Sc^{3+}}$	3d⁰	0	Colourless
$\mathrm{Ti^{4+}}$	3d⁰	0	Colourless
$\mathrm{Ti^{3+}}$	3d¹	1	Purple
$\mathrm{V^{4+}}$	3d¹	1	Blue
$\mathrm{V^{3+}}$	3d²	2	Green
$\mathrm{V^{2+}}$	3d³	3	Violet
$\mathrm{Cr^{3+}}$	3d³	3	Violet
$\mathrm{Mn^{3+}}$	3d⁴	4	Violet V²⁺, Cr³⁺ and Mn³⁺ are all violet.
$\mathrm{Cr^{2+}}$	3d⁴	4	Blue
$\mathrm{Mn^{2+}}$	3d⁵	5	Pink
$\mathrm{Fe^{3+}}$	3d⁵	5	Yellow
$\mathrm{Fe^{2+}}$	3d⁶	4	Green
$\mathrm{Co^{3+}}$	3d⁶	4	Blue
$\mathrm{Co^{2+}}$	3d⁷	3	Pink
$\mathrm{Ni^{2+}}$	3d⁸	2	Green
$\mathrm{Cu^{2+}}$	3d⁹	1	Blue
$\mathrm{Zn^{2+}}$	3d¹⁰	0	Colourless

Same colour does not mean same d count: Fe²⁺ (d⁶), Ni²⁺ (d⁸) and V³⁺ (d²) are all green.

Watch out for (4)

Past d⁵ the electrons pair up
→ The spin-only magnetic moment
Take the 4s electrons off first
→ The spin-only magnetic moment
Intensely coloured is not paramagnetic
→ Colours of the aqueous 3d ions
Copper is colourless as Cu⁺
→ Colours of the aqueous 3d ions

Oxides of Transition Metals

Reference tables (2)

Basic, amphoteric and acidic oxides9 rows

Oxide	Metal oxidation state	Character	With acid or alkali
$\mathrm{V_2O_3}$	+3	Basic	Dissolves in acid to give $\mathrm{V^{3+}}$ salts
$\mathrm{V_2O_4}$	+4	Less basic (weakly amphoteric)	Dissolves in acid to give $\mathrm{VO^{2+}}$ salts
$\mathrm{V_2O_5}$	+5	Amphoteric, mainly acidic	$\mathrm{VO_4^{3-}}$ in alkali, $\mathrm{VO_2^{+}}$ in acid The contact-process catalyst, but not a basic oxide.
CrO	+2	Basic	Dissolves in acid to give $\mathrm{Cr^{2+}}$
$\mathrm{Cr_2O_3}$	+3	Amphoteric	Reacts with both acid and alkali
$\mathrm{CrO_3}$	+6	Acidic	With water gives chromic acid, $\mathrm{H_2CrO_4}$
MnO	+2	Basic	Dissolves in acid to give $\mathrm{Mn^{2+}}$
$\mathrm{Mn_2O_7}$	+7	Acidic	With water gives permanganic acid, $\mathrm{HMnO_4}$
ZnO	+2	Amphoteric	Zincate, $\mathrm{[Zn(OH)_4]^{2-}}$ , in excess alkali

Down each metal's column of oxides, the character moves from basic to acidic as the oxidation state rises.

Structure of Mn₂O₇ and the mixed oxides6 rows

Oxide	Metal oxidation state	Structure or make-up	Point tested
$\mathrm{Mn_2O_7}$	+7	Two $\mathrm{MnO_4}$ tetrahedra sharing one O	6 terminal Mn=O, 1 bridging O, covalent green oil Mn is tetrahedral, not octahedral, and there is no Mn–Mn bond.
$\mathrm{CrO_3}$	+6	Chains of $\mathrm{CrO_4}$ tetrahedra sharing corners	Acidic, strong oxidant
$\mathrm{Mn_3O_4}$	+2 and +3	MnO· $\mathrm{Mn_2O_3}$	Mixed oxide; paramagnetic
$\mathrm{Fe_3O_4}$	+2 and +3	FeO· $\mathrm{Fe_2O_3}$	Mixed oxide; magnetite, strongly magnetic
$\mathrm{Co_3O_4}$	+2 and +3	CoO· $\mathrm{Co_2O_3}$	Mixed oxide
$\mathrm{Fe_2O_3}$	+3	One oxidation state	Not a mixed oxide

A formula M₃O₄ with an average state of +8/3 hides a +2 and a +3 metal.

Watch out for (4)

V₂O₄ with acid gives VO²⁺
→ Basic, amphoteric and acidic oxides
Ionic character falls as the oxidation state rises
→ Basic, amphoteric and acidic oxides
Mn₂O₇ is covalent, not ionic
→ Structure of Mn₂O₇ and the mixed oxides
An M₂O₃ or M₃O₄ formula alone does not decide 'mixed'
→ Structure of Mn₂O₇ and the mixed oxides

Potassium Dichromate and Chromium Compounds

Formulas (3)

From chromite ore to K₂Cr₂O₇, and chromate against dichromate · The chromate–dichromate equilibrium $\mathrm{2CrO_4^{2-} + 2H^{+} \rightleftharpoons Cr_2O_7^{2-} + H_2O} \qquad \text{Cr stays } +6$
Acidified dichromate as an oxidising agent · Electron balance with dichromate $6 \times n\left(\mathrm{Cr_2O_7^{2-}}\right) = (\text{electrons lost per reductant}) \times n(\text{reductant})$
The chromyl chloride test and blue CrO₅ · Oxidation state of Cr in CrO₅ $x + 1(-2) + 4(-1) = 0 \;\Rightarrow\; x = +6$

Watch out for (6)

Chromate to dichromate is not a redox change
→ From chromite ore to K₂Cr₂O₇, and chromate against dichromate
Only the potassium salt is a primary standard
→ From chromite ore to K₂Cr₂O₇, and chromate against dichromate
Electrons per what?
→ Acidified dichromate as an oxidising agent
The green paper is not proof of SO₂ alone
→ Acidified dichromate as an oxidising agent
CrO₅ is +6, not +10
→ The chromyl chloride test and blue CrO₅
The formula is CrO₂Cl₂
→ The chromyl chloride test and blue CrO₅

Potassium Permanganate and Manganese Compounds

Formulas (2)

Making KMnO₄: manganate, permanganate and disproportionation · Disproportionation of manganate $\mathrm{3\overset{+6}{Mn}O_4^{2-} + 4H^{+} \rightarrow 2\overset{+7}{Mn}O_4^{-} + \overset{+4}{Mn}O_2 + 2H_2O}$
Permanganate as an oxidant: acid against neutral · Two media, two products $\text{acid: } \mathrm{Mn^{+7} \rightarrow Mn^{2+}}\ (5e^{-}) \qquad \text{neutral/faintly alkaline: } \mathrm{Mn^{+7} \rightarrow MnO_2}\ (3e^{-})$

Watch out for (4)

Manganate +6, permanganate +7
→ Making KMnO₄: manganate, permanganate and disproportionation
Peroxodisulphate goes all the way to permanganate
→ Making KMnO₄: manganate, permanganate and disproportionation
Permanganate oxidises; it never reduces
→ Permanganate as an oxidant: acid against neutral
Count the water of crystallisation when the question does
→ Permanganate as an oxidant: acid against neutral

Lanthanoids and Actinoids

Reference tables (3)

Lanthanoid configurations and 4f counts15 rows

Element (Z)	Atom	M³⁺ ion	Other common ion
La (57)	[Xe]5d¹6s²	4f⁰, colourless	Shows only +3
Ce (58)	[Xe]4f¹5d¹6s²	4f¹	Ce⁴⁺, 4f⁰
Pr (59)	[Xe]4f³6s²	4f²	Pr⁴⁺, 4f¹
Nd (60)	[Xe]4f⁴6s²	4f³	Nd²⁺ 4f⁴; Nd⁴⁺ 4f²
Pm (61)	[Xe]4f⁵6s²	4f⁴	Shows only +3
Sm (62)	[Xe]4f⁶6s²	4f⁵	Sm²⁺, 4f⁶
Eu (63)	[Xe]4f⁷6s²	4f⁶	Eu²⁺, 4f⁷ Eu²⁺ and Gd³⁺ are the two 4f⁷ ions.
Gd (64)	[Xe]4f⁷5d¹6s²	4f⁷	Shows only +3
Tb (65)	[Xe]4f⁹6s²	4f⁸	Tb⁴⁺, 4f⁷
Dy (66)	[Xe]4f¹⁰6s²	4f⁹	Dy⁴⁺, 4f⁸
Ho (67)	[Xe]4f¹¹6s²	4f¹⁰	Shows only +3
Er (68)	[Xe]4f¹²6s²	4f¹¹	Shows only +3
Tm (69)	[Xe]4f¹³6s²	4f¹²	Tm²⁺, 4f¹³
Yb (70)	[Xe]4f¹⁴6s²	4f¹³	Yb²⁺, 4f¹⁴
Lu (71)	[Xe]4f¹⁴5d¹6s²	4f¹⁴, colourless	Shows only +3

The +3 ion always has Z − 57 electrons in 4f; the ions in the last column reach 4f⁰, 4f⁷ or 4f¹⁴, or come close.

Lanthanoid ions outside the +3 state7 rows

Ion	4f configuration	Why it exists	Behaviour
Ce⁴⁺	4f⁰	Noble-gas (Xe) core	Strong oxidant; E° = +1.74 V back to Ce³⁺ The noble-gas core favours forming Ce⁴⁺, but Ce³⁺ is still the more stable state in water.
Tb⁴⁺	4f⁷	Half-filled 4f	Stronger oxidant than Ce⁴⁺; found in $\mathrm{TbO_2}$
Pr⁴⁺, Nd⁴⁺, Dy⁴⁺	4f¹, 4f², 4f⁸	Stabilised only in the solid oxide	Found only as $\mathrm{MO_2}$ ; oxidants
Eu²⁺	4f⁷	Half-filled 4f after losing 6s²	Strong reductant; turns into Eu³⁺
Yb²⁺	4f¹⁴	Full 4f after losing 6s²	Reductant; diamagnetic
Sm²⁺	4f⁶	Close to 4f⁷	Reductant
Ln³⁺ (all)	4f¹ to 4f¹⁴	Loss of 6s² and one more electron	The stable state of every lanthanoid

+4 ions are oxidants and +2 ions are reductants, because each tends to return to +3.

Actinoids compared with lanthanoids6 rows

Property	Lanthanoids	Actinoids
Subshell being filled	4f, deeply buried	5f, less buried, reaches further out
f electrons in bonding	Very little	To a far greater extent
Oxidation states	Mostly +3; a few +2 and +4	+3 common; up to +7 (Np) in the first half
Contraction along the series	Lanthanoid contraction	Actinoid contraction: larger from element to element
Radioactivity	Only Pm	All of them
Example configuration	Gd [Xe]4f⁷5d¹6s²	Cm [Rn]5f⁷6d¹7s²

Almost every actinoid difference traces back to 5f orbitals being less buried than 4f.

Watch out for (6)

The 5d electron in Gd and Lu does not change the ion
→ Lanthanoid configurations and 4f counts
Isoelectronic means the same total, Z minus charge
→ Lanthanoid configurations and 4f counts
A noble-gas core does not make Ce⁴⁺ the stable state
→ Lanthanoid ions outside the +3 state
4f⁷ does not stop Eu²⁺ reducing
→ Lanthanoid ions outside the +3 state
Name the right contraction
→ Actinoids compared with lanthanoids
Cm has eight unpaired electrons
→ Actinoids compared with lanthanoids

Qualitative Analysis of Ions

Reference tables (3)

Cation groups and their group reagents7 rows

Group	Cations	Group reagent	Precipitated as
Zero	$\mathrm{NH_4^{+}}$	No group reagent; heat with NaOH	Ammonia gas, confirmed with Nessler's reagent
I	$\mathrm{Pb^{2+}}$	Dilute HCl	White $\mathrm{PbCl_2}$
II	$\mathrm{Pb^{2+}}$ , $\mathrm{Cu^{2+}}$ , $\mathrm{Cd^{2+}}$ , $\mathrm{As^{3+}}$	$\mathrm{H_2S}$ in dilute HCl	Sulphides: PbS and CuS black, CdS and $\mathrm{As_2S_3}$ yellow Pb²⁺ shows up in group I and again in group II, because PbCl₂ is partly soluble.
III	$\mathrm{Fe^{3+}}$ , $\mathrm{Al^{3+}}$ , $\mathrm{Cr^{3+}}$	$\mathrm{NH_4OH}$ with $\mathrm{NH_4Cl}$	Hydroxides: $\mathrm{Fe(OH)_3}$ reddish-brown, $\mathrm{Al(OH)_3}$ white, $\mathrm{Cr(OH)_3}$ green
IV	$\mathrm{Zn^{2+}}$ , $\mathrm{Mn^{2+}}$ , $\mathrm{Co^{2+}}$ , $\mathrm{Ni^{2+}}$	$\mathrm{H_2S}$ in $\mathrm{NH_4OH}$	Sulphides: ZnS white, MnS buff, CoS and NiS black
V	$\mathrm{Ba^{2+}}$ , $\mathrm{Sr^{2+}}$ , $\mathrm{Ca^{2+}}$	$\mathrm{(NH_4)_2CO_3}$ in $\mathrm{NH_4OH}$	White carbonates
VI	$\mathrm{Mg^{2+}}$	No group reagent; ammonium phosphate	White $\mathrm{MgNH_4PO_4}$

Acidic H₂S catches only group II; alkaline H₂S catches group IV as well, which is why group II must be removed first.

Confirmatory tests and the colours they give11 rows

Ion	Reagent	Observation	Product
$\mathrm{Cu^{2+}}$	$\mathrm{K_4[Fe(CN)_6]}$ in acetic acid	Chocolate-brown precipitate	$\mathrm{Cu_2[Fe(CN)_6]}$
$\mathrm{Fe^{3+}}$	$\mathrm{K_4[Fe(CN)_6]}$	Prussian blue precipitate	$\mathrm{Fe_4[Fe(CN)_6]_3}$
$\mathrm{Fe^{3+}}$	KSCN	Blood-red colour	$\mathrm{[Fe(SCN)]^{2+}}$
$\mathrm{Zn^{2+}}$	$\mathrm{K_4[Fe(CN)_6]}$ , after neutralising	White or bluish-white precipitate	$\mathrm{K_2Zn_3[Fe(CN)_6]_2}$
$\mathrm{Ni^{2+}}$	Dimethylglyoxime in $\mathrm{NH_4OH}$	Brilliant red precipitate	$\mathrm{[Ni(dmg)_2]}$ , five-membered chelate rings
$\mathrm{Co^{2+}}$	$\mathrm{KNO_2}$ in acetic acid	Yellow precipitate	$\mathrm{K_3[Co(NO_2)_6]}$
$\mathrm{Mn^{2+}}$	NaOH, then left in air	White precipitate turning brown	$\mathrm{MnO(OH)_2}$
$\mathrm{Mg^{2+}}$	Ammonium phosphate in $\mathrm{NH_4OH}$	White crystalline precipitate	$\mathrm{MgNH_4PO_4}$
$\mathrm{NH_4^{+}}$	Nessler's reagent, $\mathrm{K_2[HgI_4]}$ in KOH	Brown precipitate	Iodide of Millon's base
$\mathrm{PO_4^{3-}}$	Ammonium molybdate in $\mathrm{HNO_3}$	Canary-yellow precipitate	$\mathrm{(NH_4)_3PO_4 \cdot 12MoO_3}$
$\mathrm{S^{2-}}$	Sodium nitroprusside	Violet colour	$\mathrm{Na_4[Fe(CN)_5NOS]}$

Ferrocyanide alone confirms three cations: brown for copper, blue for iron(III), white for zinc.

Borax beads, anion tests and Mohr's salt10 rows

Test	Conditions	Observation	Reason
Borax bead: Cu	Oxidising flame	Green when hot, blue when cold	Copper metaborate; red and opaque in the reducing flame
Borax bead: Fe	Oxidising and reducing flame	Yellowish-brown hot, yellow cold (oxidising); green (reducing)	Iron(III) metaborate; iron(II) in the reducing flame
Borax bead: Ni	Oxidising flame	Violet when hot, reddish-brown when cold	Nickel metaborate
Borax bead: Mn	Oxidising flame	Violet (amethyst), hot and cold	Manganese metaborate; colourless in the reducing flame
Borax bead: Co	Either flame	Blue, hot and cold	Cobalt metaborate
Borax bead: Cr	Either flame	Green, hot and cold	Chromium metaborate
Brown ring ( $\mathrm{NO_3^{-}}$ )	Fresh $\mathrm{FeSO_4}$ , then conc. $\mathrm{H_2SO_4}$ down the side	Brown ring where the layers meet	$\mathrm{[Fe(H_2O)_5(NO)]^{2+}}$ , Fe +1 The complex is nitrosoferrous sulphate.
Acetate ( $\mathrm{CH_3COO^{-}}$ )	Neutral $\mathrm{FeCl_3}$ , then boil	Deep red colour, then a brown-red precipitate	Basic ferric acetate, Fe +3
Chloride ( $\mathrm{Cl^{-}}$ )	$\mathrm{AgNO_3}$ in dilute $\mathrm{HNO_3}$ , then $\mathrm{NH_4OH}$	Curdy white precipitate that dissolves	AgCl, then $\mathrm{[Ag(NH_3)_2]Cl}$
Mohr's salt preparation	Dilute $\mathrm{H_2SO_4}$ added; no prolonged heating	Pale green crystals	Acid stops hydrolysis; heating would oxidise $\mathrm{Fe^{2+}}$

The bead colour depends on the metal AND on the part of the flame used.

Watch out for (6)

Mn²⁺ is group IV, Fe³⁺ is group III
→ Cation groups and their group reagents
Acid decides which sulphides come down
→ Cation groups and their group reagents
The dimethylglyoxime rings are five-membered
→ Confirmatory tests and the colours they give
Nessler's reagent has no nitrogen
→ Confirmatory tests and the colours they give
Iron in the brown ring is +1
→ Borax beads, anion tests and Mohr's salt
The acetate test needs NEUTRAL ferric chloride
→ Borax beads, anion tests and Mohr's salt

PYQ weightage by concept

21 concepts · 214 PYQs — where the marks actually sit, so you know what to drill first

Electronic Configuration and General Properties24 PYQs · 11%

Concept	PYQs	Share
Melting points, atomisation, density, catalysts and interstitial compounds	10	5%
Configurations of d-block atoms and ions	7	3%
Ionisation enthalpies across the 3d series	7	3%

Oxidation States and Electrode Potentials27 PYQs · 13%

Concept	PYQs	Share
E° values: which ions reduce acid and which oxidise	13	6%
Oxidation states of the 3d metals	10	5%
Why Cu²⁺ is the stable copper ion in water	4	2%

Magnetic Moment and Colour25 PYQs · 12%

Concept	PYQs	Share
The spin-only magnetic moment	16	7%
Colours of the aqueous 3d ions	9	4%

Oxides of Transition Metals18 PYQs · 8%

Concept	PYQs	Share
Basic, amphoteric and acidic oxides	12	6%
Structure of Mn₂O₇ and the mixed oxides	6	3%

Potassium Dichromate and Chromium Compounds26 PYQs · 12%

Concept	PYQs	Share
From chromite ore to K₂Cr₂O₇, and chromate against dichromate	11	5%
The chromyl chloride test and blue CrO₅	10	5%
Acidified dichromate as an oxidising agent	5	2%

Potassium Permanganate and Manganese Compounds28 PYQs · 13%

Concept	PYQs	Share
Making KMnO₄: manganate, permanganate and disproportionation	14	7%
Permanganate as an oxidant: acid against neutral	14	7%

Lanthanoids and Actinoids31 PYQs · 14%

Concept	PYQs	Share
Lanthanoid configurations and 4f counts	13	6%
Lanthanoid ions outside the +3 state	13	6%
Actinoids compared with lanthanoids	5	2%

Qualitative Analysis of Ions35 PYQs · 16%

Concept	PYQs	Share
Confirmatory tests and the colours they give	16	7%
Borax beads, anion tests and Mohr's salt	10	5%
Cation groups and their group reagents	9	4%

Test yourself on The d- and f-Block Elements

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Electronic Configuration and General Properties

Oxidation States and Electrode Potentials

Magnetic Moment and Colour

Oxides of Transition Metals

Potassium Dichromate and Chromium Compounds

Potassium Permanganate and Manganese Compounds

Lanthanoids and Actinoids

Qualitative Analysis of Ions

Formula & revision sheet

PYQ weightage by concept

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