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400
Democritus (400 BC)
Democritus came up with the idea of atoms. He said that everything is made up of atoms, and they are indivisible, and indestructible. -
Robert Boyle
Boyle figured that elements were composed of some kind of cell (atoms) which organized themselves to represent different elements and compounds. -
Antoine Lavoisier
He found that atoms are neither destroyed or created in a chemical reaction. -
John Dalton
Dalton’s atomic theory stated that all matter was composed of atoms which were indivisible, and indestructible. His theory also said that each compound was composed up of different ratios of different kinds of atoms. He also said that mass, and the amount of atoms cannot be lost in a reaction. -
Dmitri Mendeleev
He invented the periodic table of elements. -
Eugen Goldstein
He discovered protons. -
J.J. Thomson
He discovered the electron. -
Max Planck
When he explained the colors of hot glowing matter, he said that the energy isn’t continuous, but sent in certain amounts. This lead to Planck’s constant “h” which is represented by 6.63 x 10(E-27) erg-second. His constant is used to describe atomic behaviors of particles and waves. -
Robert Millikan
He determined the charge of electrons. -
Ernest Rutherford
He proved that atoms have a tiny nucleus, and lead other scientists to realize that the atom had smaller parts, such as electrons. He did the gold foil experiment, he shot alpha particles at a gold foil and discovered that most went through the foil, some bounced back, and very few bounced back greatly. He said that the Nucleus is small, dense, and positively charged -
Henry Moseley
Moseley found more accurate atomic numbers, and predicted atomic numbers of undiscovered elements. -
Niels Bohr
He is known for developing a model for the atom. -
Erwin Schrodinger
He took Bohr’s model of the atom, and used it to determine the likelihood of where an electron may be at any given moment. -
James Chadwick
He discovered the neutron, almost the same mass as proton, nucleus. He inspired the U.S. into serious research of the atomic bomb.
