Basic Concepts

Atom: Smallest particle of an element. e.g., He, Ne.

Molecule: Smallest particle of a substance (element or compound) capable of independent existence. e.g., H₂, H₂O.

Molecular Ion: Formed when a molecule loses or gains an electron. e.g., CH₄⁺ (Cationic molecular ion is more common).

Mass of an atom of an element compared to 1/12th of the mass of one atom of Carbon-12 (¹²C). Unit: a.m.u. (1 a.m.u. = 1.661 × 10^-24 g).

Mole: Amount of substance containing 6.02 × 10²³ particles. It is the atomic mass, molecular mass, or formula mass expressed in grams.

• 1 Mole of C = 12g
• 1 Mole of H₂O = 18g

Avogadro's Number (N_A): 6.02 × 10²³.

Study of quantitative relationships (Mass-Mass, Mass-Mole, Mass-Volume) between reactants and products in a balanced chemical equation. Assumptions: Reactants are completely converted to products; No side reactions occur.

The reactant that is consumed earlier and controls the quantity of product formed. It gives the least amount of product.

Steps to Identify:

1. Calculate moles of all reactants.
2. Calculate moles of product expected from each reactant.
3. The reactant giving the least moles of product is the Limiting Reactant.

Theoretical Yield: Amount of product calculated from balanced equation (Maximum yield).

Actual Yield: Amount of product obtained experimentally (Always less than theoretical). Reasons: Mechanical loss, side reactions, reversible reactions.

% Yield = (Actual Yield / Theoretical Yield) × 100