- Crystalline solids of non-metals comprises of covalent bonds between adjacent atoms that are strong and directional in nature due to which atoms are held very strongly at their positions all over the crystal.
Fig. Covalent bonding between Carbon and hydrogen
- They are also called giant molecules.
- These solids are very hard and brittle.
- They have extremely high melting points and may decompose before melting.
- They are insulators and do not conduct electricity.
- Diamond and silicon carbide are typical examples of such solids but Graphite is an exception as it is soft and a good conductor of electricity.
What makes graphite soft and a good conductor of electricity?
- Graphite is a covalent solid that act as a good conductor of electricity and is soft.
- The carbon atoms of graphite are prescribed in different layers and are covalently bonded to three of its surrounding atoms in the same layer.
- The fourth valence electron of each atom is present between different layers and is free to move which makes graphite a good conductor of electricity.
- The characteristic of sliding between different layers makes graphite a soft solid and a good solid lubricant.