What were the four major models of the atom that lead up to the modern day atom model?

1. The plum pudding model which was proposed by JJ Thompson. It looked like a half of a sphere, which he said was the positively charged nucleus, with a bunch of dots on it all around, which were the negative electrons.
2. The Rutherford model which was thought of by Ernest Rutherford and he proposed that there was a small, dense, positively charged nucleus with electrons orbiting in rings around it.
3. The Bohr model was proposed by Neils Bohr. It was much like Rutherford's model except Bohr said that the electrons had a set path as they orbited around the small dense nucleus, and they had specific energy levels.
4. The electron-cloud model is currently the most up to date model of the atom. It states that the nucleus was still small and positively charged, and electrons still orbited this nucleus, much like the last two models, but it introduces a new motion of the electrons. It states that there are specific regions, deemed electron clouds, where there is a higher chance of finding electrons. These regions have specific energy levels and shapes as the electron energy increases.

Ions gain or lose electrons