JSS 1: VALENCY

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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 Antimony (Sb).

              Variable valency 

Variable valency refers to the ability of an element to exhibit more than one valency in different compounds.

Examples: Iron, Copper, Lead, Nitrogen, Phosphorus, Sulphur.

  • Iron (Fe): 2 or 3 → Fe²⁺ (ferrous) and Fe³⁺ (ferric)
  • Copper (Cu): 1 or 2 → Cu⁺ (cuprous) and Cu²⁺ (cupric)
  • Lead (Pb): 2 or 4 → Pb²⁺ and Pb⁴⁺
  • Nitrogen (N): 3 or 5
  • Phosphorus (P): 3 or 5
  • Sulphur (S): 2, 4, or 6

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