Unformatted text preview: this explains thermal conductivity. The movement of cations between
layers can take place with no change in metallic bonding. This explains ductility and
4. Allotropes of carbon: Diamond, Graphite and C60 Fullerene form covalent bonds and
network solids. In diamond, each carbon is covalently bonded to four other carbon atoms
in a three dimensional tetrahedral arrangement. Diamond is very hard, stable with a very
high melting point and does not conduct electricity as all its valence electrons are involved
in covalent bonding (sp3 hybridized). Graphite has a layered structure; each layer has
carbon atoms covalently bonded to three other carbon atoms (sp2 hybridized) in a
hexagonal arrangement but with only weak van der Waals’ forces between layers.
Graphite is easy to break, and soft with lubricating qualities. Graphite is a good conductor
due to mobility of electro...
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