0The important characteristic properties of covalent compounds are : (i) Covalent compounds consist of molecules: The covalent compounds consist of molecules. They do not have ions. For example - hydrogen, oxygen, nitrogen etc. consist of H2 , O2 and N2 molecules respectively. (ii) Physical state : Weak Vanderwaal’s forces are present between the molecules of covalent compounds. So, covalent compounds are in gaseous or liquid state at normal temperature and pressure. For example: Hydrogen, chlorine, methane, oxygen, nitrogen are gases while carbon tetrachloride, ethyl alcohol, ether, bromine etc. are liquids. Glucose, sugar, urea, iodine etc. are some solid covalent compounds. (iii) Crystal structure - Covalent compounds exhibit both crystalline and non crystalline structure. (iv) Melting point and boiling point: Energy required to break the crystal is less due to the presence of weak Vanderwaal’s force, so their melting and boiling points are less. (v) Electrical conductivity - Covalent compounds are bad conductors of electricity due to the absence of free electrons or free ions. (vi) Solubility : Due to the non - polar nature of covalent compounds they are soluble in non - polar solvents like benzene, carbon tetrachloride etc. and insoluble in polar solvents like water etc.
