History of the atom

Question 1

What did John Dalton do?

Answer 1

He thought that all matter was made of tiny particles called atoms which he imagined as tiny spheres that could not be divided

Question 2

What did JJ Thomson do?

Answer 2

Discovered the electron and proposed the plum pudding model. The Plum Pudding model suggests that the atom consists of positive ‘dough’ with a lot of negative electrons stuck in it.

Question 3

What did Ernest Rutherford do?

Answer 3

Experiment to test Plum Pudding model. Positively charged alpha particles were fired at thin gold foil, most went straight through but a few scattered in different directions. This led to Rutherford to suggest a new model called the nuclear model

Question 4

What are some differences between the Plum Pudding and nuclear model?

Answer 4

In the plum pudding model there is a positive sphere with negative charge randomly placed within the sphere. No empty space. Nuclear Model there is a central positive, tiny nucleus with mostly empty space and lots of negative charges a long way from the nucleus

Question 5

Why did some aplha particles scatter?

Answer 5

Because there is a concentration of positive charge in the atom

Question 6

What did Niels Bohr discover?

Answer 6

That electrons move around in shells at certain distances from the nucleus.

Question 7

What did James Chadwick discover?

Answer 7

Discovered the neutron

Question 8

What is the radius of an atom?

Answer 8

0.1 nano metre (1x10 to the power of -10 metres)

Question 9

What is the radius of a nucleus?

Answer 9

1x10 to the power of -14 metres (1/10,000 of the radius of the atom)