Question

Give reasons for the following:
(a) Red phosphorus is less reactive than white phosphorus.
(b) Electron gain enthalpies of halogens are largely negative.
(c) `N_(2)O_(5)` is more acidic than `N_(2)O_(3)`.

Answer 1

(a) White phosphorus has regular tetrahedron shape in which each phosphorus is linked to 3 other p-atoms by covalent bonds but in red phosphorus, `P_(4)` has tetraheral structrue but these are joined together through covalent bonds to give a polymeric structure.

(b) Halogens have smallest size and have high effective nuclear charge. As a result, they readily accept one electron to acquire the stable electronic configuration of the nearest noble gas and large amount of energy is realesed. Hence, electron gain enthalpies o halogens are largesly negative.
(c) the oxidation state of N in `N_(2)O_(5)` and `N_(2)O_(3)` is +5 and +3 respectively. Higher the oxidation state of nitrogen, more is covalent character and covalent oxide are acidic nature by FAJAN RULE.