• 460


    460 BC- 370 BC
    Some things he discovered:
    *Believed matter was made up of tiny particles called atoms. Atoms could not be destroyed, created or further divided.
    *matter is composed of empty space through which atoms move.
    *different kinds of atoms have different shapes and sizes and different properties are due to this
  • Dalton

    6 September 1766 – 27 July 1844
    Some things he discovered:
    *studied numerous chemical reactions, making careful observations ad measurements along the way
    *proposed his atomic theory in 1803
    *All matter is composed of extremely small particles called atoms
    *different atoms combine in simple whole-number ratios to form compounds
    *in a chemical reaction, atoms are separated, combined or rearranged
  • JJ Thomson

    JJ Thomson
    18 December 1856 – 30 August 1940
    Some things he discovered:
    *Discovered the electron using a cathode-ray tube
    *concluded that the rays negative particles were found in all forms of matter
  • Ernest Rutherford

    Ernest Rutherford
    30 August 1871 – 19 October 1937
    Some things he discovered:
    *discovered the nucleus of atoms during his gold foil experiment
    *atom contains tiny dense center called nucleus
    *nucleus is essentially the entire mass of the atom
    *nucleus is positively charged
    *electrons move around in the empty space of the atom surrounding the nucleus
  • Henry Moseley

    Henry Moseley
    23 November 1887 – 10 August 1915
    Some information he discovered:
    *discovered that atoms of each element contain a unique positive charge in their nuclei
    *number of protons in an atom identifies it as an atom of a particular element
    *number of protons and electrons in an atom must be equal for an atom to be neutral
    *atomic number= number of protons which equals number or electrons
  • aristotle

    384-322 BC
    Some things he discovered:
    *denied the existence of atoms
    *One of his major criticisms concerned is the idea that atoms moved through empty space.
    *Did not believe that the nothingness of empty space could exist