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(460-370BC)
First proposed the existence of an ultimate particle. -
(1704)
Newton formulated a theory of light, the three laws of motion and suggested a mechanical universe with small, solid masses. Newton suggested that atoms are held together with attractions, otherwise known as forces. He also stated that "matter is formed of solid, massy impenetrable particles”. -
(1776-1844)
John proposed the Law of Multiple Proportions.
He also developed the concept of the mole and proposed a system of symbols to represent atoms of different elements. -
(1856-1940)
J.J. discovered the electron in 1897 using the cathrode ray tube.
He also studied proton and came up with the Plum Pudding model. -
(1869)
He arranged elements by atomic mass and similar properties. -
(1871-1937)
Ernest used the gold foil method to propose the nuclear atom in 1911. In 1920 he theorized the neutron. -
(1887-1915)
Modern Pt, arranged by atomic number? -
(1891-1974)
James proved the existance of the neutron in 1932. -
(1898)
Marie did research on radioactivity. she discovered polonuim in 1898, isolating radioavtive isotopes. -
(1908)
R.A. measuring charge on the election and photoelectric effect. -
(1909)
Geiger-marsden experiement discovered atomic nucleus. -
(1922)
Fundamental contributions to the understanding of atomic structure and quantum mechanics.
By expanding on Rutherford’s earlier theory Bohr published his theory which suggested that electrons travel in specific orbits around the nucleus, that outer orbits can hold more electrons than the inner orbits and that these orbits determine the chemical properties of the atom. -
Jan 13, 1939
Lise was part of a team that discovered nuclear fission.
