History of the atom

Question 1

What was the first atom

Answer 1

Democritus- 400BC
Atomos= indivisible
Looked like a plain circle

Question 2

What was the second atom

Answer 2

J.J Thompson- 1900
-Discovered electrons
-Since atoms have no charge overall, he found that the atom needed a positive charge to cancel it out. He believed that the atom was a whole positive charge with electrons embedded into it.
-Called the plum pudding model

Question 3

What was the third atom

Answer 3

Ernest Rutherford- 1910
-Found that there was a small positively charged centre to the atom. Fired positive particles at atoms and realised that they were repelled by the centre of the atom. This experiment was called the alpha scattering experiment.
-Found that most of the atom part around the nucleus was just empty space
-Called the nuclear model

Question 4

What was the fourth atom

Answer 4

Niels Bohr- 1913
-Bohr proposed that electrons have set ‘areas’ around which they can travel. They were called shells.

Question 5

What was the fifth atom

Answer 5

Rutherford (again) 1918 Chadwick 1932
-Rutherford discovered that there is a positive charge in the nucleus. He called this a proton.
-Chadwick identified the second particle and called it a neutron.