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John Dalton
Proposed the law of multiple proportions that led directly to the discovery of the atomic theory. He also proposed a system of symbols to represent atoms of different elements and also discovered colour blindness from which he suffered. -
Ernest Rutherford
Published his atomic theory describing the atom as having a central positive nucleus surrounded by negative orbiting electrons. His gold foil experiment results suggested that most of the mass of the atom was contained in the small nucleus and the rest of the atom was mostly empty space. He also proposed the existence of the third atomic particle known as the neutron. -
J.J. Thomson
He identified the negatively charged electron in the cathode ray tube. He claimed that the electron was a component of all matter and calculated the charge to mass ratio for the electron. Himself and others also studied the positive rays in the cathode ray tube and discovered that the charge to mass ratio depended on filling gas in the tube. -
Marie Curie
Worked on radioactivity and in 1898 she reported the possible existence of a new powerfully radioactive element in pitch blend ores. She then later on discovered the radioactive elements polonium and radium. -
Henry Mosely
He developed the use of x-ray spectra to study atomic theory. From this he he discovered that the wavelength of the x-rays became shorter as the atomic weight increased. -
Francis Aston
He invented the mass spectrograph which proved the extistence of isotopes. He also formulated the "whole number rule", using the existence of isotopes. -
Niels Bohr
Known for his substansial contribution to quantum theory and his noble prize - winning research on the structure of atoms. He applied quantum theory to Rutherford's atomic structure by assuming that electrons travel in stationary orbits defined by their angular momentum. This led to the calculation of possible energy levels for these orbits and the postulation that the emissions of light occur when an electron moves into a lower energy orbit. -
Erwin Schrodinger
Proposed electrons as contiuous clouds and introduced "wave mechanics" as a mathematical mode of an atom. He also developed a powerful model of an atom. -
James Chadwick
James predicted the atom would have a neutron. He established that atomic number is determined by the numbers of protons in an atom. He also discovered the fourth subatomic particle,the neutron. -
Murray Gell - Mann
He descovered the "quark" which is a fast moving point in energy and every proton and neutron has three. There are two types of quarks in the neutron and proton, up quarks and down quarks. Himself and others later constructed the quantum feild theory of quarks and gluons, called "quantum chromodynamics" which seems to account for all the nuclear particles and their strong interactions.
