State the reason why carbon can neither form C4+ cations nor anions but forms a covalent compound. Also, state the reason to explain why covalent compounds:
i) are bad conductors of electricity.
ii) have low melting and boiling point.
Atomic number of carbon is six. This means that it has four electrons in its outermost shell and it needs four more electrons to attain noble gas electronic configuration. The removal of four valence electrons will require a huge amount of energy and so it does not form C4+ cation, as the removal of four valence electrons will require a huge amount of energy. The cation formed will have six protons and two electrons. This makes it highly unstable. Carbon is unable to form C4− anion as its nucleus with six protons will not be able to hold ten electrons. Thus, carbon achieves noble gas electronic configuration by sharing its four electrons with other elements, i.e. it forms covalent compounds.
i) Due to lack of free electrons covalent compounds are bad conductors of electricity.
ii) The intermolecular forces of attraction in covalent compounds are weak. So, they have quite low melting point and boiling point.
