Electrostatic Interpretation of Atomic Bonding

As Feynman says, atoms attract when a little distance apart and they repel when too close. This short statement has a very important implication: that there is some distance in which the forces precisely balance, i.e., some sort of of equilibrium. A preferred interatomic distance. This sounds very much like an atomic bond! But why do atoms attract when they are a little distance apart and repel when squeezed together? In other words, why do atoms bond?

Let's start with a qualitative model of an atom you should be familiar with from chemistry:

• Atoms are made up of a positively charged nucleus (comprised of neutrons and protons) surrounded by negatively charged electrons.
• The electrons are not little charged cannonballs flying around in space (although this is also a useful model in some cases, just not for bonding). Rather, they exist as delocalized "probability clouds". The density of the cloud varies in space in accordance with the quantum mechanical theory. We aren't going to discuss this quantum mechanical theory. For our purposes, it is enough to qualitatively think of electrons as charge probability clouds.
• Like charges repel (i.e., positively charged nuclei repel positively charged nuclei and negatively charged electrons repel negatively charged electrons). Opposite charges attract (i.e., nuclei attract electrons)

With this in mind, play around with the model from Concord Consortium below and try to answer the question in Exercise 3.5.1 about why bonds form. Then make sure to read and understand the answer!