Question

Why are pentahalides more covalent than trihalides in group 15?

Answer 1

1)Oxidation state of +5 in pentahalides are more than +3 oxidation state , due to higher positive oxidation state in pentahalides

2)The central atom in pentahalides have large polarising power,so its central atom will tend to polarise more

3)Whereas in trihalides +3oxidation state of central atom will polarise in a much lesser extent .

Hence pentahalides are more covalent in nature because of large polarisation of bonds.

Hope it was helpful .....