Kerala SSLC Chemistry cheat sheet

Mole concept: 1 mol = 6.022 × 10^23 particles (Avogadro number); mass of 1 mol of a substance in grams equals its molar mass in g/mol.

Number of moles n = given mass ÷ molar mass; also n = volume of gas at STP (L) ÷ 22.4 L; also n = number of particles ÷ 6.022 × 10^23.

Molar volume: any gas occupies 22.4 L per mole at STP (0 °C, 1 atm); at room temperature (25 °C) the value used is about 24 L/mol.

Percentage composition of an element = (mass of that element in 1 mol ÷ molar mass of compound) × 100.

Empirical formula gives the simplest whole-number atom ratio; molecular formula = empirical formula × n, where n = molecular mass ÷ empirical formula mass.

Atomic number Z = number of protons; mass number A = protons + neutrons; in a neutral atom electrons = protons; isotopes differ in neutrons only.

Electronic configuration follows the 2,8,8,2 (K, L, M, N) filling pattern for the first 20 elements; valence electrons determine group behaviour.

Balancing equations: conserve atoms of each element on both sides; coefficients are whole numbers and subscripts in formulas are never changed to balance.

Significant figures in calculations: addition/subtraction keeps the least number of decimal places; multiplication/division keeps the least number of significant figures.

Mole concept: 1 mol = 6.022 × 10^23 particles (Avogadro number); mass of 1 mol of a substance in grams equals its molar mass in g/mol.

Number of moles n = given mass ÷ molar mass; also n = volume of gas at STP (L) ÷ 22.4 L; also n = number of particles ÷ 6.022 × 10^23.

Molar volume: any gas occupies 22.4 L per mole at STP (0 °C, 1 atm); at room temperature (25 °C) the value used is about 24 L/mol.

Percentage composition of an element = (mass of that element in 1 mol ÷ molar mass of compound) × 100.

Empirical formula gives the simplest whole-number atom ratio; molecular formula = empirical formula × n, where n = molecular mass ÷ empirical formula mass.

Atomic number Z = number of protons; mass number A = protons + neutrons; in a neutral atom electrons = protons; isotopes differ in neutrons only.

Electronic configuration follows the 2,8,8,2 (K, L, M, N) filling pattern for the first 20 elements; valence electrons determine group behaviour.

Balancing equations: conserve atoms of each element on both sides; coefficients are whole numbers and subscripts in formulas are never changed to balance.

Significant figures in calculations: addition/subtraction keeps the least number of decimal places; multiplication/division keeps the least number of significant figures.