Phosphorus has three allotropic forms : (i) white phosphorus (ii) red phosphorus and (iii) black phosphorus. Write the difference between white and red phosphorus on the basis of their structure and reactivity.

Phosphorus has three allotropic forms : (i) white phosphorus (ii) red

1.	Phosphorus has three allotropic forms : (i) white phosphorus (ii) red phosphorus and (iii) black phosphorus. Write the difference between white and red phosphorus on the basis of their structure and reactivity.
Answer» Solution :Structrue. White phosphorus CONSISTS of discrete `P_(4)` molecules in which each P is `sp^(3)`-HYBRIDIZED and lies at the corner of a tetrahedron. Thus, it has a tetrahedral structure with six P-P bonds In contrast, red phosphorus also consists of `P_(4)` tetrahedra but these are joined together through single covalent P-P bonds to form a polymeric structure Reactivity. White phosphours is much more reactive than red phosphorus. This is due to the reason that in white phosphours, the PPP angle is only `60^(@)` which is much smaller than the tetrahdral angle `(109^(@)-28^(@))`. As a result, `P_(4)` tetrahedral molecules have considerable angle strain and hence white P is very reactive. it READILY catches fire in air. Becaues of polymeric structure, red P is HOWEVER, much less reactive than white P. It is quite stable and does not catch fire in air.