In diatomic molecules, the constituent atoms exert attractive forces on each other at large distances and repulsive forces at short distances. For many molecules, the Lennard-Jones law is a good approximation to the magnitude of these forces:
Where r is the center-to-center distance between the atoms in the molecule, σ is a length parameter, and F0 is the force when r = 4. For an oxygen molecule, we find that F0 = 9.60 x 10 ─11 N and σ = 3.50 x 10&10 m. Determine the work done by this force if the atoms are pulled apart from r = 4.00 x 10─10 m to r = 9.00 x 10─10 m.