NEET Chemistry Formula Sheet 2026

n = mass / M = molecules / Nₐ = volume(STP) / 22.4L

Nₐ = 6.022 × 10²³ mol⁻¹

M = moles of solute / volume of solution (L)

% = (mass of element in 1 mol / molar mass) × 100

Simplest whole-number ratio of atoms

Divide by smallest mole value

Compare moles / stoichiometric coefficient — smallest ratio limits

rₙ = 0.529 × n² / Z Å

Eₙ = −13.6 Z² / n² eV

λ = h / mv = h / p

E = hν = hc/λ = KE + φ

1/λ = RZ²(1/n₁² − 1/n₂²)

R = 1.097 × 10⁷ m⁻¹

2n²

IE increases across period, decreases down group

Exceptions: Be>B, N>O

EN increases across period, decreases down group

F is most electronegative (4.0)

BO = (Nb − Na) / 2

FC = V − L − B/2

V=valence, L=lone pair, B=bonding electrons

Small cation + large anion → more covalent character

Triple < Double < Single

Bond strength: Triple > Double > Single

sp=linear, sp²=trigonal, sp³=tetrahedral, sp³d=TBP, sp³d²=octahedral

ΔU = q + w

IUPAC: w = work done on system

H = U + PV; ΔH = ΔU + ΔnₘRT

ΔG = ΔH − TΔS

ΔG < 0 → spontaneous; ΔG = 0 → equilibrium; ΔG > 0 → non-spontaneous

ΔH_rxn = Σ ΔH_f(products) − Σ ΔH_f(reactants)

q = nCΔT; Cp − Cv = R (per mole, ideal gas)

ΔS = q_rev / T

Kc = [Products]^coeff / [Reactants]^coeff

Kp = Kc(RT)^Δn

Δn = gaseous moles products − reactants

Q < K → forward; Q > K → backward; Q = K → equilibrium

System shifts to oppose imposed change (T, P, conc.)

pH = −log[H⁺]; pOH = −log[OH⁻]; pH + pOH = 14 (at 25°C)

Kw = [H⁺][OH⁻] = 10⁻¹⁴ at 25°C

pH = pKa + log([salt]/[acid])

Ksp = [Aⁿ⁺]^m × [Bᵐ⁻]^n for AmBn

Rate = k[A]^m[B]^n

Orders from experiment

[A] = [A]₀ − kt; t½ = [A]₀ / 2k

k = (2.303/t)log([A]₀/[A]); t½ = 0.693/k

k = Ae^(−Ea/RT)

log(k₂/k₁) = (Ea/2.303R)(1/T₁ − 1/T₂)

E = E° − (0.0592/n)log Q at 25°C

E°_cell = E°_cathode − E°_anode

w = ZIt = (MIt)/(nF)

Λm = κ × 1000 / M

M = molarity

Λ°m = ν₊λ°₊ + ν₋λ°₋

F = 96485 C/mol ≈ 96500 C/mol

Pₐ = P°ₐ × χₐ

(P° − P)/P° = χ_solute

ΔTb = i × Kb × m

ΔTf = i × Kf × m

π = iCRT

i = 1 + (n−1)α for dissociation; i = 1 − (1−1/n)α for association

M₂ = (Kb × w₂ × 1000) / (ΔTb × w₁)

Similarly for Kf

DoU = (2C + 2 + N − H − X) / 2

H adds to C with more H (electrophilic addition of HX)

Rate = k[substrate]; 3° > 2° > 1° (via carbocation)

Rate = k[substrate][nucleophile]; CH₃ > 1° > 2° (Walden inversion)

More substituted alkene = major product in elimination

RCOOH > ArOH > H₂CO₃ > ROH > H₂O > HC≡CH > NH₃

Stability: 3° > 2° > 1° carbocation (no. of α-H atoms)

2RX + 2Na → R-R + 2NaX (dry ether)

ArH + RCl → ArR + HCl (AlCl₃ catalyst)

ArH + RCOCl → ArCOR + HCl (AlCl₃)

PhO⁻Na⁺ + CO₂ → salicylic acid (125°C, 4-7 atm)

PhOH + CHCl₃ + NaOH → salicylaldehyde

R-O⁻ + R'X → R-O-R' (SN2)

ArN₂⁺ + CuX → ArX (X = Cl, Br, CN)

C=O → CH₂ (Zn-Hg/conc. HCl)

Acidic conditions

C=O → CH₂ (NH₂NH₂ / KOH / ethylene glycol)

Basic conditions

RCONH₂ + Br₂/NaOH → RNH₂ + Na₂CO₃

One carbon lost

RNH₂ + CHCl₃ + 3KOH → RNC + 3KCl + 3H₂O

Test for 1° amines

RCHO + 2[Ag(NH₃)₂]⁺ → RCOO⁻ + 2Ag↓

Aldehydes give silver mirror

CH₃CO-R + 3I₂ + 4NaOH → CHI₃↓ + RCOONa

For methyl ketones & ethanol

Decreases across period; increases down group

Cation < parent atom; Anion > parent atom

Isoelectronic: more protons → smaller

Increases down group; decreases across period

F₂ > Cl₂ > Br₂ > I₂

I⁻ > Br⁻ > Cl⁻ > F⁻

I⁻ < Br⁻ < Cl⁻ < F⁻ < OH⁻ < H₂O < NH₃ < en < CN⁻ < CO

CN = total number of donor atoms bonded to central metal