Which of the following is not a molecular crystal?

Options

A. Iodine
B. Silicon
C. Phosphorus
D. Sulphur

Answer

2

Explanation

In a molecular crystal,the lattice points are occupoed by moleucles and the attractive foces between them are van der Waals and/or hydrogen bonding.
The simplest molecular solids are the frozen noble gases,e.g solid neon. In this case the molecules are single atoms and the intermolecular interactions are London forces. These forces are nondirectional ( in constract to covalent bonding, which is directional) ,and the maximal attraction is obtained when each atoms is surreounded by the largest possible number of other atoms.
Another Example of a molecular crystal is solid sulphur dioxide `(SO_(2))` in which the predominant attractive froce is dipole-dipole interaction, Intermolecular hydrogen bonding is mainly responsible for maintaining the three dimensional ice lattice. Other Examples of molecular crystals are iodine `(I_(2))`, phosphorous `(P_(4))`, and sulphur`(S_(8))`
Because van der Waals forces and hydrogen bonding are generally quite weak compared with the covalent and ionic bonds, molecular crystals are more easily broekn apart than ionic and crystals indeed most molecular crystals melt below `100^(@)`
Silion germanium and grey tin (a nonmetallic allotrope) are covalent crystals and have "Diamond " structure.