Download Models of the atom

The Models of the Atom
• 400 B.C.- Democritus - matter could not be divided - he used the
Greek word atomos which means indivisible
•384-322 B.C. – Aristotle- 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. This view held for 2000 years primarily because Aristotle was
the tutor of Alexander the Great.
• 1800-1900 – Dalton- according to his Dalton Atomic Theory he came
up with the Billiard Ball Model – atoms are solid and indivisible
•1900 – Thompson – Plum pudding model (raisin bun) – negative
electrons in a positive framework
• 1910- Rutherford – atoms are mostly empty space- negative
electrons orbit a positive nucleus
Watch movie clip
Bohr - electrons orbit the nucleus in shells, and electrons can be
bumped up to a higher shell if energized