CHEMISTRY

                          Radicals   A radical is a group of atoms that acts as a single unit and carries either a positive or negative charge during a chemical reaction. Radicals behave as units and take part in the formation of chemical compounds. For example: SO₄²⁻ — Sulphate radical NO₃⁻ — Nitrate radical OH⁻ — Hydroxide radical NH₄⁺ — Ammonium radical               Types of Radicals The two types of radicals are: I. Positive radicals II. Negative radicals                   Positive Radicals These are radicals that carry a positive charge . Examples:             Negative Radicals These are radicals that carry a negative charge. Examples: Characteristics of Radicals A radical consists of two or more atoms in most common cases. The atoms in ...

Valency is the combining power of an element. It determines how an element combines with other elements to form compounds. CLASSIFICATION OF ELEMENTS BASED ON VALENCY Elements may have different valencies, as I. Monovalent elements  II. Divalent elements III. Trivalent elements IV. Tetravalent elements V. Pentavalent elements I. Monovalent Elements They are elements with a valency of 1. Examples: Potassium (K), Sodium (Na), Hydrogen (H), Fluorine (F), and Chlorine (Cl). II. Divalent Elements They are elements with a valency of 2. Examples: Calcium (Ca), Barium (Ba), Magnesium (Mg), Oxygen (O), and Zinc (Zn). III. Trivalent Elements They are elements with a valency of 3. Examples: Aluminium (Al), Iron (Fe³⁺), Boron (B), and Nitrogen (N). IV. Tetravalent Elements They are elements with a valency of 4. Examples: Carbon (C), Silicon (Si), and Lead (Pb⁴⁺). V. Pentavalent Elements They are elements with a valency of 5. Examples: Phosphorus (P), Arsenic (As), and Antim...