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The concept of allotropy was proposed by a Swedish chemist Jons Jakob Berzelius in 1841. The word allotropy is taken from a Greek word Allotropia meaning changeableness. Allotropy refers to the existence of an element in one or more than one physical forms. Allotropes may show variations in physical and chemical properties.

The two elements of Group 14 that show allotropy are Carbon and Silicon. Carbon has many allotropes because of its valency. Though there are diamond, graphite, fullerene, nanotubes, graphene etc here we will be discussing two very well-known allotropes of carbon that are Graphite and diamond. Presently around 500 hypothetical allotropes of carbon are there. Diamond is a 3-dimensional structure where tetrahedral structures combine together, and its hardness makes it perfect for industrial and jewelry applications. Graphite is a 2-dimensional structure where layers of hexagonal rings are stacked together. The structures of both are represented below.

Allotropes of carbon

There are two allotropes of silicon at room temperature. One is crystalline allotrope, and another is amorphous allotrope. A single crystal of Si can be doped with other elements such as Ge, P, B, and Ga and can be used in the manufacturing of several electronic devices such as rectifiers, solar cells, and transistors.