Class 12

Chalcogens The elements oxygen (O), sulphur (S), selenium (Se), tellurium (Te) and polonium (Po) constitute group 16 elements of the periodic table.   These are named as oxygen family after the name of the first member of the group. The first four elements of this group are collectively known as chalcogens (meaning ore forming elements) because many metal ores occur as … [Read more...] about Physical Properties of Group 16 Elements

Oxoacids of Phosphorus – The p-Block Elements – Class 12 Some Important Oxoacids of Phosphorus   (1) Phosphinic acid or Hypophosphorous acid, H3PO2 Preparation of Phosphinic acid or Hypophosphorous acid (1) It is prepared by heating phosphorus with alkalies like barium hydroxide when precipitate of barium phosphate is formed. The precipitate is separated and heated … [Read more...] about Oxoacids of Phosphorus

Halides and Oxides of Phosphorus – The p-Block Elements – Class 12 Halides of Phosphorus   Phosphorus forms two types of halides i.e., phosphorus trihalides (covalency of P =3) PX3 (X = F, CI, Br, I) and phosphorus pentahalides PX5 (X = F, Cl, Br) (covalency of P=5).    With chlorine it forms: (1) Phosphorus trichloride (2) Phosphorus … [Read more...] about Halides and Oxides of Phosphorus

Phosphorus and Phosphine – The p-Block Elements – Class 12 Phosphorus Phosphorus is produced by heating bone ash or phosphate rock with silica (SiO2) and coke in an electric furnace at 1775 K.   The reactions taking place are : 2Ca3(PO4)2 + 6SiO2 -------> 6CaSiO3 + P4O10   P4O10 +10C -------> 10 CO + P4   The vapour of phosphorus thus produced upon … [Read more...] about Phosphorus and Phosphine

Nitric Acid – The p-Block Elements – Class 12 Nitric Acid (HNO3)   The common oxoacids of nitrogen are given below :     Nitric acid is a very strong oxidising agent.Nitrogen shown an oxidation state of +5 in nitric acid. Laboratory Preparation of Nitric Acid In the laboratory, nitric acid can be prepared by heating sodium or potassium nitrate with … [Read more...] about Nitric Acid