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John Dalton
Dalton put forth the Atomic Theory, in which he hypothesised that matter consists of invisible particles called atoms. His theory continued with all atoms of a given element are identical in mass and properties. He stated that compounds are formed by a combination of two or more different kinds of atoms. Finally, he stated that a chemical reaction is a rearrangement of atoms. -
Eugen Goldstien
Eugen Goldstein was a German physicist. He was the first to discover that positively charged particles formed when electrons are removed from the gas particles in a cathode-ray tube. He was also very interested in electrical discharges in moderate to high vacuums. Finally his work suggested that there was a presence of the proton – a positively charged particle, later discovered by Ernest Rutherford. -
J.J. Thompson
In 1906 J.J. Thompson was awarded the Nobel Prize in Physics for the discovery of the electron. Beginning in 1894, while working with cathode rays, Thompson developed better techniques and equipment that helped him to calculate the mass of particles. He concluded that the particles that made up gases were universal. He determined that all matter was made up of particles, smaller than atoms originally called corpuscles, now called the electron. -
Ernest Rutherford
Ernest Rutherford was awarded the Nobel Prize in Chemistry in 1908. However, his greatest contribution to our understanding of the atom came in 1910. His Atomic Theory described the atom as having a centrally positive nucleus surrounded by negative orbiting electrons. Rutherford`s famous gold foil experiment, led to his conclusion that most of the mass of the atom was contained in the nucleus and the rest was mostly empty space. -
Neils Bohr
Winner of the 1922 Nobel Prize in Physics, Niels Bohr greatly expanded the understanding of the structure of the atom. Working under Thompson and then Rutherford, Bohr combined theories from different researchers to develop his theory. The Bohr Model of the Atom described electrons travelling in orbits around the atom`s nucleus with the chemical properties of each element being determined by the number of electrons in the outer orbit of its atoms. -
James Chadwick
James Chadwick was awarded the Nobel Prize in Physics in 1935. In February of 1932, while working in his laboratory, Chadwick confirmed the existence of the neutron. This discovery revolutionized the understanding of the nucleus of atoms. The discovery of the neutron made it possible for scientists to explain variance in spin rates that were occurring in atoms when it was previously believed that nuclei were made only of protons.
