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John Dalton
Believed that the entire atom was a indivisible sphere. It could not be destroyed or reconstructed. This was based on experiments with gas and combustion, and experiments about how proportion never changed. With this evidence and some assumptions about atom's indestructable nature, he formed his theory. -
JJ Thompson
During three experiments, JJ Thompson discovered electrons. In his experiments, he used a vacuum-sealed tube, and then sent electrons traveling towards the opposite end. He also used pudding with figs. These backed up the existence of electrons. -
Rutherford
He believed the atom was made up of positive charges in the nucleus and negative charges orbiting around it. He discovered this by shooting alpha particles into gold foil and recording when they bounced back. -
Niels Bohr
Believed that the electrons that orbited the protons were restricted to a certain path. Much like the planets orbiting the sun. The evidence backing up this theory is successive ionization. -
James Chadwick
In 1932, Chadwick discovered the neutron in the center of an atom. With this discovery, he could now back up isotopes' existence. For his evidence he shot alpha particles at beryllium atoms. He discovered that isotopes have neutrons and protons too.
