History of the atom

• It had all started off with Aristotle’s theory that everything was made up of an even smaller particle.

Aristotle

•  Dalton reintroduced the atom and stated his own atomic theory

• JJ Thomson introduced the plum pudding model in which explains that the atom contains electron that are negatively charged and protons that are positively charged



JJ Thomson

• He also discovers that the atom is made of an equal amount of positive and negative particles
• Ernest Rutherford later used his own experiment to discover that both electrons and protons were smaller particles within the atom

• He states that the nucleus is positively charge and the area in the atom that left is mostly empty and contains electrons
• J Chadwick is able to discover the neutron in which Rutherford had previously predicted

• Niels Bohr then comes up with a diagram with the different electron shells that surround the nucleus

• He hypothesized that only certain electrons of certain energy can occupy the electron shell
•  In a way he also discovers the valence shell that would help in identifying the reactivity of the atom