Arrangement of electrons

• 1913 - Bohr said atoms have a positive nucleus but negative electrons circling
• 1926 - Schrodinger published his wave equation and could use it to predict the movement of electrons
• 1932 - Chadwick discovered the neutron
• Electron shells

  1st shell holds up to 2 electrons

  2nd shell holds up to 8 electrons

  3rd shell holds up to 18 electrons