Greek Atomism

2. Greek Atomism • The Greeks were the first people to develop an atomic theory. • They could not perform formal scientific experiment but they reason that if they keep dividing an object like paper into two over and over it will eventually come to a point where matter was indivisible. • They called this indivisible matter the atom.

3. Solid sphere • Around 1800s Dalton proposed the solid sphere model of the atom. • He found out that all compounds were made of elements that combined in whole number ratios. • He could not really explain how exactly the atoms combined but believed that all atoms of the same element were identical and that atoms were indivisible.

4. Plum pudding • 100 years later plum pudding model of the atom became accepted. • This model was tested by JJ Thompson based on the results of the electrons. • He found out that atoms are not the smallest things.. Electrons were smaller.

5. ERNEST RUTHERFORD • Ernest Rutherford, proved the pudding model to be wrong. Rutherford’s experiment was to emit alpha particles towards a thin old sheet, then determine

6. Nuclear model • The plum pudding model didn’t last long because Rutherford conducted the gold foil experiment almost two decades later. • In his experiment he fired alpha particles at the a thin gold foil. If the alpha particles went through JJ Thompson would have been right but Rutherford found out that some reflected. • This experiment led to the discovery of the nucleus.

7. Gold Foil experiment