Timeline of the Atom

Timeline created by 14AShenk
  • Antoine Lavoisier

    Antoine Lavoisier
    He found the law of conservation of mass: Matter cannot be created or destroyed.
  • Joseph Proust

    Joseph Proust
    He created the principle known as the law of definite proportions: specific substances always contain elements in the same ratio by mass.
  • John Dalton

    John Dalton
    Found that all matter is composed of atoms, all matter of the same element have the identical atoms, atoms of different elements are not alike, and atoms unite in simple ratios to form compounds.
  • John Dalton No. 2

    John Dalton No. 2
    He discovered the Law of Multiple Proportions: The ratio of masses of one element that combine with a constant mass of another element that can be expressed in small whole numbers.
  • J. L. Gay-Lussac

    J. L. Gay-Lussac
    He found that under constant conditions the volumes of reacting gases and gaseous products are in the ratio of small whole numbers.
  • Amadeo Avagadro

    Amadeo Avagadro
    He stated that equal volumes of gases, under the same conditions, have the same number of molecules.
  • Dimitri Mendeleev

    Dimitri Mendeleev
    He proposed the periodic law and developed the first periodic table.
  • Henri Becquerel

    Henri Becquerel
    He found that matter containing uranium exposes sealed photographic film.
  • J.J. Thomson

    J.J. Thomson
    researched cathode rays and was able to determine the ration of an electron’s charge to its mass.. Found that cathode rays consist of electrons.
  • Marie and Pierre Curie

    Marie and Pierre Curie
    Found that rays are given off by the elements uranium and radium.
  • Robert Millikan

    Robert Millikan
    Obtained the first acurate measurement of an electrons charge.
  • Henry Mosely

    Henry Mosely
    Found out about the atomic number by studying x-rays with anodes of different materials. Finding that the number of protons determines the identity of the element and the number of neutrons determines the particular isotope of the element.
  • Lord Rutherford

    Lord Rutherford
    he predicted the existence of the neutron. He also proposed the nuclear atom as the result of the gold-foil experiment
  • Walter Bothe

    Walter Bothe
    Obtained the first evidence of the neutron.
  • James Chadwick

    James Chadwick
    He discovered the neutron.