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465 BCE
Democritus
Throughout 470-360 BC Democritus was the founder of the existence of atoms and he believed atoms were indivisible and indestructible. -
Antoine Lavoiser
Between 1772 and 1794, Antoine Lavoiser studied chemical reactions. He created the Law of Conservation, which states that matter cannot be destroyed. He also said that matter can be rearranged, but never disappear. -
John Dalton
In 1803, John Dalton revealed his atomic theory. This theory stated that all matter was made up of atoms. His theory also stated that Atoms are invisible and indestructible. -
Dmitri Mendeleev
In 1869 Mendeleev was the founder the atomic mass of an element (63 elements he did this to). -
Eugene Goldstein
Throughout 1811-1891 Goldstein was the founder of protons. He discovered them by an experiment called Cathode Rays which knocked electrons of atoms and attract them to a positively charged electrode. -
J.J. Thomson
In 1897, J.J. Thomson discovered the electron. He discovered the electron, by showing through experiments that cathode rays were negatively charged. Along with this, he studied positively charged particles in neon gas. After this, he created his atomic model, which explained the electrical charges that were found, due to the electrons within the model. -
Robert Millikan
Throughout 1908-1917 Millikan studied atoms. He is known for his Oil Drop Experiment which measured the mass of an electron. 1/1840 the mass of a hydrogen atom, has one unit of negative charge. -
Ernest Rutherford
In 1911 Rutherford was the founder of the nucleus. The nucleus is a positively charged core. -
Henry Moseley
Throughout 1912 and 1913 Moseley was the founder of the Periodic Table -
Niels Bohr
In 1913 Niels Bohr proposed his theory for the hydrogen based atom. His theory was based on the quantum theory. His theory stated that electrons move around the nucleus, but only in a certain path. Niels Bohr said that when there is lower energy, a light quantum is given off. -
Max Planck
In 1918 he won the nobel prize for a theory that he created. This theory was the quantum theory of energy. This theory proposes the idea that shows natural state of matter and behavior of matter. This is observed on the atomic and subatomic levels. -
Erwin Schrodinger
In 1926, Erwin Schrodinger created the quantum mechanical model of the atom. This model mathematically described the likelihood of an electron being in a certain position. -
James Chadwick
In 1932, James Chadwick discovered what would later be known as the neutron. He did this by combining beryllium atoms with alpha particles, which created a radiation. Chadwick said that this radiation was composed of particles with electrical charges. These particles are now known as the neutron. -
Werner Heisenberg
In 1936 Heisenberg contributed to the atomic theory by interpreting the behavior of atoms.
