History of the Atom

Question 1

What is the relative mass of a proton?

Answer 1

1

Question 2

What is the relative mass of a neutron?

Answer 2

1

Question 3

What is the relative mass of an electron?

Answer 3

1/2000

Question 4

What is the total number of protons & neutrons in an atom called?

Answer 4

The mass number.

Question 5

How is the electronic structure of a carbon atom represented?

Answer 5

2 electrons on the first shell

4 electrons on the outer shell

Question 6

What was the plum pudding / cookie model?

Answer 6

A positively chared ‘ball’ with negatively charged electrons in it.

Question 7

What was Bohr’s model?

Answer 7

Electrons in fixed orbits surrounding a small positively charged nucleus.

Question 8

What was Rutherford’s nuclear model?

Answer 8

A small positively charged nucleus surrounded by a ‘cloud’ of negative electrons.

Question 9

In 1932 James Chadwick discovered a neutral sub-atomic particle found in the nucleus. What was this particle called?

Answer 9

Neutron.

Question 10

How did Rutherford explain scattering of alpha particles by gold atoms?

Answer 10

• Fired positively charged particles at thin gold foil
• They repelled back towards their source
• Suggested that the positive charge must be concentrated at a tiny spot in the centre of the atom.