Covalent network crystals

Characteristics of covalent network crystals are as follows:

i. The constituent particles in covalent network solids are atoms.

ii. The atoms in these crystals are linked by a continuous system of covalent bonds, producing a rigid three-dimensional network that forms a giant molecule -- the entire crystal is, in effect, a single molecule.

iii. As a result of this rigid, strongly bonded structure, covalent network crystals are very hard -- in fact the hardest and most incompressible of all materials -- and they have high melting and boiling points.

iv. The electrons are localised within the covalent bonds and hence are not mobile, so covalent network solids are poor conductors of heat and electricity. …