HOW TO MAKE STRUCTURES OF ALLOTROPES OF CARBON
#The allotropes of carbon:
Three forms (or ‘allotropes’) of pure carbon are diamond, graphite and buckminster fullerene (or ‘buckyballs’). In all three allotropes the carbon atoms are joined by strong covalent bonds but in such different arrangements that the properties of the allotropes are very different.
A diamond is one giant molecule of carbon atoms.
Every atom in a diamond is bonded to its neighbours by four strong covalent bonds leaving no free electrons and no ions. That’s why diamond does not conduct electricity. The bonding also explains the hardness of diamond and its high melting point. A lot of energy would be needed to separate atoms so strongly bonded together.
Graphite is formed from carbon atoms in layers.
Each carbon atom is bonded into its layer with three strong covalent bonds. This leaves each atom with a spare electron, which together form a delocalised ‘sea’ of electrons loosely bonding the layers together. These delocalised electrons can all move along together – making graphite a good electrical conductor. Because the layers are only weakly held together they can easily slip over one another: hence the slipperiness of graphite. Melting graphite is not easy however. It takes a lot of energy to break the strong covalent bonds and separate the carbon atoms.
Buckminster Fullerene is one type of fullerene. Fullerenes are made from carbon atoms joined together to make balls, ‘cages’ or tubes of carbon.
The tube fullerenes are called nanotubes which are very strong and are conductors of electricity. Their unusual electrical properties mean that nanotubes are used as semiconductors in electronic circuits. Their strength makes them useful in reinforcing structures where exceptional lightness and strength are needed for example, the frame of a tennis racket. They’re also used as a platform for industrial catalysts.