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384
384BC - Artistotle
The controbution Aristotle made to the Atomic theory was that He believed in the four elements of air, earth, water and fire. Aristotle felt that regardless of the number of times you cut a form of matter in half, you would always have a smaller piece of that matter. -
460
460BC - Democritus Develops the Idea of Atoms
He pounded up materials in his pestle and mortar until he had reduced them to smaller and smaller particles which he called atoma. He believed that once you had cut a piece of bread in half so much to the point you can no longer cut it, yo would be left with atomas. -
- John Dalton
Suggested that all matter was made up of tiny spheres that were able to bounce around with perfect elasticity and called them Atoms. -
and 1904 - Joseph John Thompson
Found that atoms could sometimes eject a far smaller negative particle which he called an electron. Thompson develops the idea that an atom was made up of electrons scattered unevenly within an elastic sphere surrounded by a soup of positive charge to balance the electron's charge, the first ,major breakthrough of its kind. -
- Ernest Ruthorford
Ernest Ruthorford bombarded a piece of gold foil for an experiment which was soon to become famous. In this experiment Ruthorford found out (by using small radium atoms). About 1 in ever 8000 atoms hit something and rebounded on an angle, but all the others went through. He concluded that there must be something stopping these particles from passing through, as it must have a positive charge abd called it a nucleus. -
- Neils Bohr
Bohr refined Rutherford's idea by adding that the electrons were in orbits. Rather like planets orbiting the sun. With each orbit only able to contain a set number of electrons. -
- Erwin Schrödinger
Erwin discovered that electrons did not just orbit, but were more random and hyperactive. -
- James Chadwick
Discover that not only did the nucleus contain protons, but it also contained neutrons. Regarded as the founder of neutrons.