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Democritus
A discovery Democritis made in 400BC lead him to think that everything was made up of atoms. Depending on how the atoms were arranged, the density of anything was changed. -
Isaac Nawton
Isaac Newton discovered that there are forces between atoms at affect how they are composed. He publicised that atoms can affect the properties of everything. Atoms are what makes everything work. -
G.J. Stoney
Stoney thought that a particle smaller then an atom existed that was electrified and held the atom together. This helped us understand that there are other particles within atoms that are electrically charged. -
John Dalton
John Dalton theorised that elemental atoms have a unique atomic weight and can be placed in a specific order to form the periodic table of elements. -
Albert Einstein
Albert Einstein developed the theory of relativity, one of setting stones of modern physics. Einstein thought of the most famous equation in the world: E = mc2. He also discovered the photoelectric effect and also invented quantum theory. -
J.J. Thomson
Thomson confirmed that atom particles do contain electrons. He discovered that cathode rays could be deflected by an electric field that confirmed that these rays were negatively charged. -
Max Planck
Planck discovered quantum theory by studying how light and radiation worked. He thought that if something was too small it would just destroy its self rather then keep going. -
Hantaro Nagaoka
Nagaoka developed an incorrect “planetary model” of the atom that was based on the stability of Saturn’s rings. It was a massive nucleus that had electrons revolving around it. -
Robert Millikan
Millikan measured the electric charge of an electron and so proved the quantity of electrons was always constant then demonstrating the structure of electricity. -
Ernest Rutherford
Rutherford created a model of the atom. It was a very small charged nucleus, with electrons circling it. He also suggested the existence of neutrons that could stop the effect of charged protons, stopping the nuclei breaking. -
H.G.J. Moseley
Mosely created the X-ray and he also discovered that if an elements atomic number of protons were the same lead to the periodic table of elements being arranged by this instead of mass -
Niels Bohr
Bohr suggested that when an atom is heated, the electrons can jump to higher levels and when it cools they slow down to a lower level. He also suggested that the levels around the nucleus had a maximum capacity of 2 electrons -
James Chadwick
Chadwick used alpha particles as an experiment and discovered that there was a neutral atomic particle close to a proton.
