J Thomson discovered the first subatomic particle, which was the electron. His model of the atom was proved with the experiment of scaffold raise. Thomson used magnets and electrically charged plates to deflect caffold raise. Thomson also stated that the particles must be made out of negatively charged particles. Thomson said that nitrogen is the smallest atom of the atom. Thomson's model of the atom only lasted for about 10 years.
In 1909, Ernest Rutherford created another model of the atom that was even better than J.J Thomson's of 1897. Rutherford's team proved that his model of the atom was better than Thomson's by using an experiment. During the experiment, Rutherford found that a beam of alpha particles shot at a thin piece of foil, passed through. Occasionally, some of the particles would have been deflected back. Rutherford said that, witnessing this was the most incredible event of his life. When Rutherford realized positive particles attracted negative particles, in the atom he wondered why the atom wasn't collapsing.
This problem that Rutherford was confused about, was solved in 1913 by Niels Bohr. Bohr suggested that the negatively charged particles had an orbit around the positively charged nucleus. In Bohr's model, the negatively charged particles all have fixed energy levels that are circling around the nucleus at fixed distances. The further the electron gets from the nucleus, the higher the energy levels are. Also in Bohr's model of the atom, electrons are able to jump from one orbit to another. .
Bohr's model has electrons on the outer shell that determine and elements atomic number. His model has a certain number of electrons orbiting the nucleus. The valence electron determines that chemical property of an atom. That's how the atomic number comes out of an element. The higher the atomic number is the more chemical properties it has.
Hydrogen has only 1 electron and 1 proton and has no neutrons.