GENERAL PROPERTIES OF COVALENT COMPOUNDS
Compounds whose molecules consist of atoms held together by covalent bonds are called covalent compounds. In general, the covalent compounds have the following properties:
1. State of existence. Atoms in covalent compounds are joined together by mutual sharing of electrons. The covalent compounds, therefore, exist as individual molecules. The intermolecular forces in these compounds are usually weak. Therefore, they exist in liquid or gaseous state. However, a few covalent compounds also exist in the solid state, e.g., urea, sugar, etc. It may be noted that some covalent substances exist as giant network structures with very strong interatomic covalent bonds. They do not exist as simple molecules. Common examples are diamond, silicon, silica (SiO2) graphite, etc.
2. Non-conducting. Covalent compounds are generally poor conductors of electricity in the fused or dissolved state due to non-existence of ions.
3. Low boiling and melting points. The attractive forces between the molecules of covalent compounds are generally weak. As a result, lesser amount. of energy is needed to overcome these intermolecular forces. Thus, these compounds usually have low melting and boiling points.
4. Solubility. Covalent compounds are usually insoluble or less soluble in water and in other polar solvents. However, these are more soluble in non-polar solvents.