Department of Physics and Astronomy

Atoms bonded though shared electrons can be modeled with springs.  When the atoms are pushed together, they tend to repel.  When the atoms are separated, they tend to attract.  It can also show that rigid materials are not necessarily rigid at the molecular level!  The model can also show how stress or strain can cause a "delta L".  (For example, hanging a mass on a wire of length L will cause a small increase in its length.)