Describe the forces both attractive and repulsive that occur as two atoms move closer together.

The answer is:

1) As the atoms approach to each other, the net force of attraction increases (electrostatic attraction between the protons in nuclei and the electrons in the orbitals), at a certain optimal distance between atoms (bond length), the net attractive force is maximized.

2) If the atoms move closer than the optimal distance, repulsive force exceeds attractive force and atoms do no form molecule.