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JEE Main · Cheatsheet

Chemistry Quick Revision

Physical + inorganic memorisation table + organic reactions & mechanisms.

Mole concept & stoichiometry

m/M = N/Nₐ = V/22.4 (STP)

M (molarity)

mol/L

m (molality)

mol/kg solvent

Dilution

M₁V₁ = M₂V₂

% purity

(pure/impure)×100

Empirical → molecular

MF = n·EF; n = M_mol/M_emp

Atomic structure

Quantum numbers: n, l, m_l, m_s. l=0 s,1 p,2 d,3 f.
Aufbau, Hund, Pauli; anomalies Cr, Cu.
Nodes: radial n−l−1, angular l.
Photoelectric: KE = hν − φ; stopping potential eV₀.
de Broglie λ = h/p; Heisenberg Δx·Δp ≥ h/4π.

Chemical bonding

Ionic: transfer of e⁻; Fajans' rules.
Covalent: shared pair; polar vs non-polar.
Hybridisation: sp (180°), sp² (120°), sp³ (109.5°), sp³d (TBP), sp³d² (oct).
VSEPR: lp–lp > lp–bp > bp–bp repulsion.
MO: BO = (Nb − Na)/2; O₂ paramagnetic.
H-bonds: HF > H₂O > NH₃ (per bond strongest HF).

States of matter (gases)

PV = nRT

Dalton

P_total = ΣP_i

Graham

r₁/r₂ = √(M₂/M₁)

van der Waals

(P + an²/V²)(V − nb) = nRT

Critical

T_c=8a/27Rb, P_c=a/27b²

v_rms

√(3RT/M)

Thermodynamics & thermochemistry

ΔU

q + w

ΔH

ΔU + Δn_g RT

ΔG

ΔH − TΔS

ΔG°

−RT ln K = −nFE°

Hess

ΔH depends only on states

Cp − Cv

Equilibrium (chem + ionic)

Kc(RT)^Δn

10⁻¹⁴

pH + pOH

Buffer

pH = pKa + log([A⁻]/[HA])

Ksp AB

s²

Ksp A₂B

4s³

Redox & electrochemistry

Nernst

E = E° − (0.0591/n) log Q

ΔG°

−nFE°

log K

nE°/0.0591

Faraday

w = ZIt; Z = E/F

Λm

κ·1000/M

Kohlrausch

Λ°m = ν₊ λ°₊ + ν₋ λ°₋

Chemical kinetics

1st order k

(2.303/t) log([A]₀/[A])

t½ (1st)

0.693/k

0 order

[A]₀−[A] = kt; t½ = [A]₀/2k

Arrhenius

k = A e^(−Ea/RT)

log k₂/k₁

Ea/2.303R (1/T₁ − 1/T₂)

Solid state

SC 52%, BCC 68%, FCC/HCP 74%.
Atoms/cell: SC=1, BCC=2, FCC=4.
Voids in FCC: 4 oct + 8 tet.
Density ρ = zM/(a³Nₐ).
Defects: Schottky (density↓), Frenkel (density=), F-centre.

Solutions & colligative

Raoult

P = x·P°

ΔTb

Kb·m·i

ΔTf

Kf·m·i

iCRT

1 + α(n−1) [ionise]

Surface chemistry

Physi vs Chemi adsorption (H bond vs covalent).
Freundlich x/m = kP^(1/n).
Colloids: Tyndall, Brownian, electrophoresis.
Hardy–Schulze: charge on ion coagulating opposite sol.
Emulsion: O/W (milk), W/O (butter).

Periodic properties & p-block trends

Across period: r ↓, IE ↑, EN ↑.
Down group: r ↑, IE ↓, EN ↓.
IE order (2nd period): Li<B<Be<C<O<N<F<Ne.
EA anomaly Cl>F; EN: F>O>N=Cl>Br>I.
Diagonal relationship: Li–Mg, Be–Al, B–Si.
Inert pair effect: heavier p-block prefers lower OS.

Coordination compounds

Werner primary/secondary valency.
Ligand types: mono/bi/poly-dentate; ambidentate NO₂⁻/ONO⁻.
IUPAC: ligands alphabetical, then metal (OS in Roman).
Isomerism: geo (cis/trans), optical, linkage, ionization, coord.
CFT: Δ_o splits; low spin strong field ligand.
μ = √(n(n+2)) BM.
Spectrochemical: I⁻<Br⁻<Cl⁻<F⁻<OH⁻<H₂O<NH₃<en<CN⁻<CO.

d & f block

Variable OS; coloured; magnetic; catalytic.
Lanthanoid contraction → similar 4d/5d radii.
KMnO₄: Mn 7→2 (acidic), 7→4 (neutral/alkaline).
K₂Cr₂O₇: Cr 6→3.
Actinoids more reactive; radioactive.

GOC — effects & intermediates

Inductive: −NO₂, −CN withdraw; alkyl donates.
Mesomeric: −OH, −NH₂, −OR donate; −NO₂, −CHO withdraw.
Hyperconjugation: no. of α-H; explains stability 3°>2°>1°>Me carbocation.
Aromaticity: cyclic, planar, conjugated, (4n+2)π.
Intermediates: carbocation, carbanion, radical, carbene, nitrene.

Organic reactions summary

SN1: 3°, protic, racemisation; SN2: 1°, aprotic, inversion.
E1: 3°, heat; E2: strong base, 2°/3°, Saytzeff.
Markovnikov: HX to unsym alkene (H to more-H C); anti-Mark HBr/peroxide.
Aromatic EAS: nitration, sulph, halog, F-C alkyl/acyl.
Named reactions: Aldol, Cannizzaro, Wurtz, Sandmeyer, Reimer–Tiemann, Kolbe, Hoffmann bromamide (amide → 1° amine, C↓1), Gabriel (1° amine).
Reduction: LiAlH₄ strong (ester→alc), NaBH₄ mild (ket/ald), Rosenmund (acyl chloride→ald).
Grignard: RMgX + carbonyl → alcohol on workup.

Biomolecules & polymers

Carbs: aldose/ketose, D-/L-, α-/β-anomer, reducing/non-reducing.
Amino acid: zwitterion, isoelectric pt.
Proteins: 1° (seq), 2° (α-helix, β-sheet), 3°, 4°; denaturation.
DNA: A=T (2H), G≡C (3H); RNA: U; ribose.
Polymers: addition (PE, PS), condensation (nylon-6,6, terylene).
Biodegradable: PHBV, nylon-2-nylon-6.