It is the second member of group 15 (VA) of the Periodic table. Due to larger size of P, it cannot form stable Pπ - Pπ bonds with other phosphorous atoms where as nitrogen can form Pπ – Pπ bonds .

(1) Occurrence: Phosphorous occurs mainly in the form of phosphate minerals in the crust of earth. Some of these are :

(i) Phosphorite Ca3 ( PO₄ )₂ , (ii) Fluorapatite Ca₅ ( PO₄ )₃ F , (iii) Chlorapatite 3 Ca₃ ( PO₄ )₂. CaCI₂ , (iv) Hydroxyapatite; Ca₅ ( PO₄ )₃ OH . Phosphates are essential constituents of plants and animals. It is mainly present in bones, which contains about 58% calcium phosphate.

(2) Isolation : Elemental phosphorus is isolated by heating the phosphorite rock with coke and sand in an electric furnace at about 1770K,

2Ca₃ ( PO₄ )₂ + 6SIO₂ ——→ 6CaSiO₃ + P₄O₁₀; P₄O₁₀ + 10C ——→ P₄ + 10CO

(3) Allotropic forms of phosphorus : Phosphorus exists in three main allotropic forms,