He concluded that all of the positive charge and virtually all of the mass of an atom are concentrated in one tiny area and the rest of the atom is mostly empty space. Rutherford called the area of concentrated positive charge the nucleus.

How did Rutherford interpret the fact that most of the a particles seemed to pass right through the foil? The foil was so thin that the a particles were able to pass in between the tiny, solid gold atoms. Gold is malleable so the gold atoms moved out of the way of the a particles and allowed them to pass through.

Rutherford’s gold foil experiment showed that the atom is mostly empty space with a tiny, dense, positively-charged nucleus. Based on these results, Rutherford proposed the nuclear model of the atom.

The alpha particles that were fired at the gold foil were positively charged. These experiments led Rutherford to describe the atom as containing mostly empty space, with a very small, dense, positively charged nucleus at the center, which contained most of the mass of the atom, with the electrons orbiting the nucleus.

“stay in touch” implies regular contact, whereas “keep in touch” implies occasional contact. “stay in touch” means you are already in touch and want to continue that connection, whereas “keep in touch” can be used for existing and new connections.

Strictly speaking, no – there really isn’t a difference between them. It’s possible that “stay in touch” is a little more insistant and sincere than saying “keep in touch”, which is kind of a casual and reflexive remark (like saying “see you later” when you have no idea when or if you’ll ever see that person again).