"Two different forms of carbon - diamond and graphite have different structures and very different physical properties even though their chemical…

In diamond, each carbon atom is bonded to four other carbon atoms forming a rigid three dimensional structure. This makes diamond the hardest substance known.

In graphite, each carbon atom is bonded to three other carbon atoms in same plane giving a hexagonal array being placed in layers one above the other this makes graphite a smooth and slippery substance.

Both diamond and graphite are composed of carbon, therefore their chemical properties are same. / Both are allotropic form of Carbon.

(i) If carbon atom loses four electrons forming \(\displaystyle \mathrm{C}^{4+}\) cation, it would require a large amount of energy to remove four electrons leaving behind a carbon cation with six protons in its nucleus holding two electrons.

(ii) If carbon atom gains four electrons forming \(\displaystyle \mathrm{C}^{4}\) anion, it would be difficult for a nucleus with six protons to hold on ten electrons, that is four extra electrons.

Carbon atom overcomes this problem by sharing its valence electrons with other atoms of carbon or with atoms of other elements.