Phosphorus Discovered In 1669 by Henning Brandt in

Phosphorus Discovered: In 1669 by Henning Brandt in urine. 1 st Ionization energy 1011. 8 kj/mol Earth`s crust abundance 0. 1 % Common oxidation num. -3, +5 Electron configuration [Ne]3 s 23 p 3 Physical state Solid Melting point 44. 20 C Color Red, White, Black Boiling point 2770 C Density 1. 8 g/ml

• Phosphorus, is called ‘spreader of light’ in Latin language. • It is very reactive nonmetal. • It is essential constituent of living organisms, found in bones and teeth. Many proteins, in seeds, eggs, nerve tissues and brain cells contain phosphorus. It makes up 1% of human body.

Allotropes of Phosphorus White Phosphorus • White-yellow waxy solid. • Ignites in moist air, stored under water. • P 4 tetrahedral structure. • Poisonous, unstable. Garlic smell. • illuminates at night. • Does not conduct electricity. • Insoluble in water. Red Phosphorus • White- Red powder. • Ignites in air above 300 0 C. • Not poisonous. • No smell. • No illumination. • Sublimes at 593 0 C. • Used on match boxes.

• Exist in nature as PO 4 -3 minerals. The most abundant is Ca 3(PO 4)2 and apatite Ca. F 2. 3 Ca 3(PO 4)2. • Very important for living organisms, exist in skeleton and teeth as Ca 3(PO 4)2 intensively.

Occurrence of Phosphorus • White phosphorus is sometimes called yellow phosphorus because it turns lemon-yellow on exposure to light. It changes slowly and spontaneously to red phosphorus. 300 o. C P (white) → P (red) I 2 • Black phosphorus is the most stable allotrope of phosphorus. Obtained by heating white phosphorus under high pressure. It is semiconductor.

• White phosphorus is prepared by heating mixture of sand, coke and calcium phosphate in electric furnace to about 1500 0 C. Heat 2 Ca 3(PO 4)2(s) + 6 Si. O 2(s) → 6 Ca. Si. O 3(s) + P 4 O 10(g) Heat P 4 O 10(g) + 10 C(s) → P 4(g) + 10 CO(g) • The phosphorus vapor is obtained from the above reactions condensed to a liquid under water, and than further cooled and pressed into sticks.

Chemical Properties of Phosphorus • Reacts with some metals; 3 Ba + 2 P → Ba 3 P 2 • Reacts with halogens; 2 P + 5 I 2 → 2 PI 5 • Forms P 2 O 3 or P 2 O 5 with oxygen; P 4 + 3 O 2 → 2 P 2 O 3 • Reacts with strong acids; P 4 + 5 HNO 3 → H 3 PO 4 + 5 NO 2 + H 2 O • Reacts with strong bases; 2 P 4+ 3 Ba(OH)2+ 6 H 2 O → 2 PH 3+ 3 Ba(H 2 PO 2)2

Compounds of Phosphorus Oxides, P 4 O 6 • White crystalline, wax-like solid. Its vapor smells like garlic and poisonous. • Prepared by the reaction; P 4(s) + 3 O 2(g) → P 4 O 6(s) • Dissolves slowly in cold water. P 4 O 6 + 6 H 2 O → 4 H 3 PO 3 6 P 4 O 6 + 24 H 2 O → 15 H 3 PO 3 + PH 3 + 8 P(red) • Reacts with nonmetals. P 4 O 6 + 6 Cl 2 → 4 POCl 3 + O 2

Oxides, P 4 O 10 • White crystalline, White solid formed by reaction of oxygen with P 4. React with water vigorously. P 4 + 5 O 2 → P 4 O 10(s) + 6 H 2 O(l) → 4 H 3 PO 4(aq) Hot Phosphoric Acid, H 3 PO 4 • Colorless solid, • Sold as solution of water, • Used in fertilizers, soft drinks, detergent, • Obtained by the reaction, P 4 O 10(s) + 6 H 2 O(l) → 4 H 3 PO 4(aq)

Uses of Phosphorus • In fertilizers, pesticides, detergents, water softeners, baking powder, fireworks and match boxes…etc