Question
What do you expect the nature of hydrides if formed by elements of atomic numbers 15, 19, 23, 44 with dry dihydrogen? Compare their behaviour towards water.
Solution
(i) The element having Z = 15 is a non-metal (i.e. P), therefore it forms covalent hydride (i.e. PH3).
(ii) The element having Z = 19 is an alkali metal (i.e. K), therefore it forms ionic or saline hydride (i.e. K+ H-).
(iii) The element having Z = 23 is a transition metal (i.e. V) of group 5, therefore it forms an interstitial or metallic hydride (i.e. V H1.6).
(iv) The element having Z =44 is a transition metal (i.e. Ru) of group 8, therefore it does not form any hydride.
Behaviour towards the water. Only ionic hydrides react with water evolving H2 gas.
