Atomic Theory (Quantum Theory)

Rutherford’s Gold Foil Experiment showed that:

  1. Most of the mass of an atom (and all of its positive charge) is concentrated in a very small region in the center of an atom (the nucleus).
  2. Most of the volume of an atom is empty space.

However, Rutherford also envisioned the electrons as moving around the nucleus similar to the way in which planets orbit the sun. Today we know that planetary motion is not a good model for the movement of electrons around the nucleus of an atom. Instead, we think of the electrons as a cloud of charge surrounding the nucleus.