Atomic Theory

By J.P568
  • Period: 400 to

    Atomic Theory

  • 440


    Democritus had a theory that if you break a rock down to tiny bits it would not be able to be broken down anymore. He called these tiny bits atomos. In his time his idea was unpopular but this had started the idea for atomic theory.
  • Joseph Priestly

    Joseph Priestly had isolated an element from the air and discovered oxygen but did not realize what it was when he discovered it.
  • John Dalton

    John Dalton had read about Democritus's work and expanded on it which what started the modern atomic theory. John Dalton thought that atoms were small spheres and that each element had its own type of atom and a unique mass
  • Dmitri Mendeleev

    Mendeleev had grouped the elements by the atomic number creating a table which shows that certain elements that were grouped by their atomic number had the same properties
  • J.J. Thomson

    Thomson had created a new model for atoms where atoms were made of even smaller particles.. He found this out by using electric currents in glass tubes and produced particles called electrons
  • James Chadwick

    A student of Rutherford, Chadwick expanded on the nucleus concept and discovered that the nucleus has neutral and positive particles inside it.
  • Ernest Rutherford

    Rutherford had done an experiment similar to Thomson's and had found the nucleus and revised Thomsons model adding the nucleus as the center of the atom with the electrons surrounding it.
  • Niels Bohr

    Borh had studied the properties of electrons in atoms and created a simplified version of the atomic model in which he suggested that electrons are arranged in shells which can only hold a certain amount of electrons in them. He found out that electrons move between shells by losing or gaining energy. Today people still use Bohr's model to describe the particles in the atom.
  • Friedrich Hund

    Hund was the first to work out how electron pairing works