the ‘s’ orbitals of two hydrogen atoms to give σsp3 -s bonds. Due to the lone pair – lone pair repulsions and lone pair – bond pair repulsions HOH decreases from 109028/(expected for sp3– tetrahedral hybridisation) to104031/.CH4, C2H4-and C2-H2molecules and their structures will be explained in carbon and its compounds chapter later in this class.

From the above table we understand that ionic compounds like NaCl are solids at room temperature. Polar compounds like HCl possess properties like melting point, boiling point, reactivity, solubility etc, between those of ionic compounds and covalent compounds. If the covalent bond is between atoms of two different elements, the shared electron pair shift more towards the atom of more electronegative element. Thus within the molecule the more electronegative atom bears a partial negative charge and the less electronegative atom bears a partial positive charge. A molecule of this type which is neutral but possesses partial charges on the atoms within the molecule is called a polar molecule and the bond is called a polar covalent bond or partial ionic and partial covalent bond.

In ionic compounds there exist stronger electrostatic forces of attractions between the oppositely charged ions of these compounds. Therefore, they are solids with high melting points and boiling points. Based