New Zealand born scientist tested Thompson’s model of the atom while working in England

Rutherford’s famous “Gold Foil” experiment led him to include a nucleus in his atomic model

Rutherford shot positively charged particles at a very thin foil of pure gold

INTERESTING FACT #1!Gold (Au) is a very malleable metal 1cubic

cm of gold ( roughly the size of a Lego block) can be hammered into a sheet 1 meter by 1 meter in size, that’s twice the size of the surface of your desk)

Rutherford obtained the positive charge particle from a radioactive substance he placed in a lead block with a tiny hole in it so the particle could escape

INTERESTING FACT #2!Lead (Pb) is a metal element that is used to provide protection from radioactivity. The apron dentists ask you to wear during x-rays is lined with lead. As you can tell it is a very heavy metal.

In the experiment most high speed positive particles went right through the gold foil, however some bounced back

WHY? …. Because of the gold’s NUCLEUS!

Rutherford discovered the nucleus the center of the atom

He also discovered that the nucleus contains most of the atoms mass

He calculated that that comparing the size of the nucleus to other atomic sub-particles was like comparing a football field to a green pea

Based on the “Gold Foil” experiment Rutherford revised the existing atomic model to include a nucleus

Similar to Thomson’s model except that all of the atom’s positive charge and mass were concentrated at a tiny point in the centre of the atom and the electrons surrounded this point

Chadwick was Rutherford’s student and he refined the concept of the nucleus

He discovered that the nucleus contains neutral (no charge) particles called neutrons and positive charge particles called protons

Each neutron has almost the same mass as each proton in the atom

Danish physicist that helped transform Rutherford’s model to a model that we use today

Bohr suggested that electrons surround the nucleus in specific energy levels called energy shells

He found that electrons jump between these energy shells by gaining or losing energy

The max number of electrons in the first three energy shells are; 2, 8, and 8 respectively

Most advanced and accurate model of the atom

Electrons exist in specific energy levels that surround the nucleus in a form resembling a cloud