Group 1 Elements

Potassium chlorate is called Berthelot salt, which on thermal decomposition gives potassium chloride and oxygen gas.

(i) The alkali metal superoxides contain ion, which has an unpaired electron, hence they are paramagnetic in nature. (ii) The basic character of alkali metal hydroxides increases on moving down the group. (iii) The conductivity of alkali metal chlorides in their aqueous solution increases on moving down the group because in aqueous solution alkali metal chlorides ionise to give alkali metal ions. On moving down the group the size of alkali metal ion increases, thus degree of hydration decreases, due to this reason their conductivity in aqueous solution increases on moving down the group. Ionisationin (iv) Thus, basic nature of carbonates in aqueous solution is due to anionic hydrolysis.

As the size of alkali metal ion increases, lattice enthalpy decreases and hence the stability of the corresponding metal hydride decreases.

Amongst alkali metals, is most reactive because of its lowest IE.

Calcium silicophosphate (a mixture of ) is called Thomas slag.

Calcium gives brick red colour and barium gives apple green colour in flame test.