Lesson 3: History of models of atoms by deluded Chemists/Physists (Interrupted by fire drill, henceforth very short.)

John Dalton thought that an atom is a sphere of matter that is the same throughout.

J.J. Thomson discovered that all atoms contain electrons, which are tiny, negatively charged particles. Thomson proposed that an atom is a sphere of positive charge. The electrons are mixed uniformly in the sphere.

Rutherford updated the model of the atom. He hypothesized that almost all the mass and all the positive charge of an atom is concentrated in an extremely tiny nucleus at the center of the atom.

Bohr described the atom as a planetary arrangement: electrons orbiting the nucleus.