In 400 B.C. A Greek physicist, Democritus proposed the atomic model which was just a ball of neutral charge that was arranged in a grid to make minerals and elements
Democritus' atomic model
A few hundred years later, in 1803, John Dalton proposed daltons atomic model, he found different weights in atom in water and found different atoms existed for different things. He also proposed that atoms were indestructible and indivisible
Daltons atomic model
In 1897. J.J. Thomson proposed that there were negatively charged electrons (Plums) that orbited the positively charged nucleus (pudding) he called this theory the Plum Pudding model.
Thomsons atomic model
In 1911 Ernest Rutherford described the atom as a tiny dense positively charged core called the nucleus and there were electrons that orbited around it.
In 1913 Niels Bohr proposed the Bohr model where he said that electrons orbit at different levels around the nucleus
In 1924 Erwin Schrödinger proposed the quantum mechanical model of the atom where the electron is more likely to exist in a more dense part of the electron cloud than a less dense part.