M Beasley

  • 101

    Democritus ~ 429 BC

    First person to think of the atom.
    Thought atom was a solid sphere.
  • 102

    Aristotle ~ 400 BC

    Thought everything was made of air, earth, water, and fire.
    Didn't think things were made of atoms like Democritus did.
  • Sir Isaac Newton

    Tiny pieces of mass "swimming" around.
  • Dalton

    1. Matter-composed of atoms. (T)
    2. Atoms-can't be destoyed or made. (F)
    3. All atoms of same elements are identical. (F)
    4. Different elements = different atoms (T)
    5. Chemical reactions occur when atoms are rearranged. (T)
    6. Compounds are formed from atoms of a different elements. (T) Thought that the atoms was a circle.
  • Becquerel

    Helped discover radioactivity.
    Thought atom was a solid sphere.
  • J.J. Thomson

    Discovered negative particles.
  • Robert Andrews Millikan

    Measured the mass and charge of an electron.
  • Rutherford

    Gold foil experiment.
    Proved nucleus was in the middle of the atom and electrons surround it.
  • Bohr

    Depicted atom as small, positively charged nucleus surrounded by electrons.
  • Francis Aston

    Discovery of isotopes of non-radioactive elements.
  • Erwin Schrodinger

    Consists of nucleus and clouds.
    Discovered formula that calculated the odds of where an electron might be.
    Proved Bohr incorrect.
  • Chadwick

    Discovered the neutron.