Concept of Allotropes: An element, in different forms, having different physical properties but similar chemical properties is known as allotropes of that element. Carbon has three well known allotropes which are graphite, diamond and buck minster fullerene. These are formed by carbon atoms.
Each carbon atom is bonded to three other carbon atoms in the same plane giving a hexagonal array. One of these bonds is a double-bond, and thus the valency of carbon is satisfied. Graphite structure is formed by the hexagonal arrays being placed in layers one above the other. Graphite is also a very good conductor of electricity unlike other non-metals
Each carbon atom is bonded to four other carbon atoms forming a rigid three-dimensional structure. Diamond is the hardest substance known while graphite is smooth and slippery. Diamonds can be synthesised by subjecting pure carbon to very high pressure and temperature. These synthetic diamonds are small but are otherwise indistinguishable from natural diamonds.
It form another class of carbon allotropes. The first one to be identified was C-60 which has carbon atoms arranged in the shape of a football. Since this looked like the geodesic dome designed by the US architect Buckminster Fuller, the molecule was named fullerene
Glassy or vitreous carbon is a class of carbon widely used as an electrode material in electrochemistry as well as in prosthetic devices and high-temperature crucibles. Its most important properties are high temperature resistance, hardness, low density, low electrical resistance, low friction, low thermal resistance, extreme resistance to chemical attack, and impermeability to gases and liquids.
Carbon nanotubes are cylindrical carbon molecules that exhibit extraordinary strength and unique electrical properties and are efficient conductors of heat. Carbon nanobuds are newly discovered allotropes in which fullerene-like “buds” are covalently attached to the outer side walls of a carbon nanotube. Nanobuds therefore exhibit properties of both nanotubes and fullerenes.
Allotropes of carbon:
Single walled carbon nano tube
BPCS Notes brings Prelims and Mains programs for BPCS Prelims and BPCS Mains Exam preparation. Various Programs initiated by BPCS Notes are as follows:-