Covalent bond in carbon
- The elements having less than 8 electrons in their outermost shell always have a tendency to attain an octet in order to attain a noble gas configuration by gaining or losing electron forming ionic compounds.
- In case of carbon with atomic number 6 there are four electrons in its outermost shell due to which it is termed as tetravalent.
- It gains or loses four electrons to attain the nearest noble gas configuration.
- Carbon has two possibilities to attain noble gas configuration.
(i) One of the possibilities is to attain four electrons and form C4– anion. But it will be difficult for the nucleus to hold four more electrons firmly.
(ii) Another possibility is to lose four electrons forming C4+ cation. But this will also be difficult due to the requirement of large energy to lose four electrons from the outermost shell. As a result the atom will contain six protons and two electrons.
- Therefore carbon shares its valence electrons present in its outermost shell with the electrons in the outermost shell of the combining atoms of other elements.
- Due to this sharing of four electrons of carbon with the electrons of other combining atoms, carbon is said to form covalent bonds. For example, carbon shares these electrons with four atoms of hydrogen.
Fig. Sharing of electron between carbon and hydrogen
- The carbon-carbon bond is very strong and hence stable.
- Compounds possessing covalent bonds have strong bonds within the molecule, but intermolecular forces are small leading to low melting and boiling points of these compounds.
- Due to the sharing of electrons no charged particles are formed i.e. no ions are formed due to which covalent compounds are poor conductors of electricity.