We know that an atom tends to attain stability by acquiring the electronic configuration of its nearest noble gas. This can be achieved in anyone of the following manners during chemical combination:
1. By the transfer of electron(s) from one atom to another
2. By the sharing of valence electrons between the two combining atoms
There must be some kind of force which binds the atoms together in a molecule. The attractive force which holds together two atoms, two molecules, two ions or a combination of these is known as a chemical bond.
The two modes of attaining the electronic configuration of the nearest noble gas give rise to two types of bonds-the electrovalent bond and the covalent bond.