Step-by-step explanation:
An atom consists of electrons, protons, and neutron. The protons and neutrons are present inside the nucleus whereas the electrons are present outside the nucleus.
These electrons revolve around the nucleus in circular motion. Therefore, an electron pair surrounds the central atom of a molecule. It is known that an electron contains a negative charge and like charges repel each other.
Hence, in an atom the force of repulsion between electron pairs pulls the atoms away from each other.
As a result, a molecules atoms are as far away from each other as they can get.