Contributors to the Atomic Theory

By gp10060
  • 470 BCE

    Democratus

    Everything is made of atoms and is not physically divisible, but is geometrically divisible. Model- Round sphere with no protons, neutrons, or electrons

  • Joseph Proust

    Theorized the definite proportion of atoms in a compound. Model- If there are 2 atoms of hydrogen and 1 atom of oxygen in a water molecule then if there are 2 molecules of water, there are 4 atoms of hydrogen and 2 atoms of oxygen.

  • Dalton

    Each element is made of small atoms. Different elements have atoms of different mass. Model- Atoms as tiny solid balls

  • Thomson

    Atom is a positively charged sphere that has electrons embedded in it. Model- Muffin with berries scattered throughout it

  • Henry Moseley

    Theorized that all atoms of a given element have the same number of protons in the nucleus.

  • Rutherford

    Concluded that the atom is mostly empty space. Electrons orbit randomly around a small, positively charged nucleus. Model- Plum pudding model, atoms are like plums and the nucleus is like the pit

  • Bohr

    Determined that electrons are not randomly located around the nucleus. Model- Showed electrons moving in specific layers, or shells.