Give reason why carbon can neither form C 4+ cations nor C 4– anions, but forms covalent compounds. Also, state the reason to explain why covalent compounds are bad conductors of electricity and have low melting and boiling points?
(i)Carbon has tetravalency which means that 4 electrons are present in its outermost shell. However, it cannot gain or lose electrons because:
- If it gains electrons to form C 4- , the 6 protons will not be able to hold 10 electrons and so it becomes unstable.
- In order to lose electrons to form C 4+ , a lot of energy will be required so this also cannot exist.
- Free electrons are required to conduct electricity.
Covalent compounds are formed by sharing of electrons so no free electrons are available to conduct electricity. Therefore, covalent compounds are bad conductors of electricity.
- Covalent compounds have molecules of 2 different elements sharing electrons, so they have weak forces of attraction . Therefore, lesser energy is required to break the bond and hence they have low melting and boiling points.