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Dalton's Atomic Theory
Chemisty History
John Dalton publishes his Atomic Theory which states that all matter is composed of atoms, which are small and indivisible.
Picture:http://bin.sulinet.hu/kemia/anyag/kemtort/dalton/dalton.jpg -
The Proton
Chemistry History
Eugene Goldstein discovered positive particles by using a tube filled with hydrogen gas. The charge is equal and positive to the electron. -
Pitchblend
PictureChemistry History
Henri Becquerel was studying the fluorescence of pitchblend when he found a property of the pitchblend compound. Pitchblend gave a fluorescent light with or without the help of sunlight. -
J. J. Thomson
pictureChemistry HistoryThomson placed the Crookes' tube within a magnetic field. He found that the cathode rays were negatively charged and that each charge had a mass ratio of 1.759E8 coulombs per gram. He concluded that all atoms have this negative charge . He renamed them to be electrons. -
Mass of Electron
Chemistry HistoryRobert Milikian discovered the mass of an electron by introducing charged oil droplets into an electrically charged field. -
Rutherford
Chemistry HistoryErnest Rutherford sent a radioactive source through a magnetic field. Some of the radioactivity was deflected to the positive plate; some of it was deflected to the negative plate; and the rest went through the magnetic field without deflection. This lead to the discovery of three types of radioactivity. -
Neils Bohr
Molecular ExpressionsNeils Bohr created a theory for the atom. The work said that electrons travel only in certain orbits and that any atom could exist only in a discrete set of stable states. Bohr then held that the outer orbits, which could hold more electrons than the inner ones, determine the atom's chemical properties and conjectured that atoms emit light radiation when an electron jumps from an outer orbit to an inner one. -
Protons within a Nucleus
Chemistry HistoryHenry Moseley attempts to use x-rays to determine the number of protons in the nucleus of each atom. He was unsuccessful because the neutron had not been discovered yet. -
The Nuetron
Chemistry History
James Chadwick had the discovery of the nuetron.
