What are the force that holds two atoms together?

Answer 1

We've seen that an atom consists of a whole bunch of different kinds of particles. The next logical question (and we do want to be logical, don't we?) is: "What holds it all together?" What makes all this stuff an atom, rather than just a bunch of stuff flying past each other?

Well, there are basically two things that hold it together. Two forces, that is. The first of these has to do with electric charge, something I mentioned on the previous page. Electric charge comes in two varieties: positive and negative. The main carriers of positive charge are protons, while the main carriers of negative charge are electrons. (Within protons and neutrons, the quarks themselves carry charge, but this is only important to us in that the net charge of a proton or neutron is equal to the sum of the charges of all its quarks: zero for a neutron, and a small positive amount for a proton.) Every proton carries exactly the same amount of positive charge, and every electron carries a negative charge exactly opposite that of a proton. There are other particles with electric charge, but they tend to live only a very short time before they decay, and so they're mostly unimportant for atoms.

The significance of electric charge is that it forms the basis for electric force. Any particle with electric charge will exert a force on any other particle with charge. (And vice versa, of course.) And there are two rules describing the electric force.

1. Opposite charges attract; like charges repel.
2. The force gets weaker as the two charges get farther apart. LOL Anywaz, gtg