7.3 FINDING THE NUCLEUS

Question 1

Scientists who contributed to develop a model of the atom:

Answer 1

1. Ernest Rutherford
2. Marie Curie
3. Hans Geiger
4. Ernest Marsden
5. Niels Bohr
6. Joseph John Thomson
7. James Chadwick

Question 2

Testing the Plum Pudding model:

Answer 2

1895: Ernest Rutherford moved to England to study under Thomson.
Rutherford collaborated with Hans Geiger and Ernest Marsden.
Set up apparatus to test the plum pudding model in 1909.

Question 3

Prediction for the Plum Pudding model

Answer 3

Positive particles go straight through the foil = Plum Pudding model is correct

Question 4

Result for the Plum Pudding model

Answer 4

Particles bounced backwards = Plum Pudding model is wrong

Question 5

A new model for the atom:
1911 Rutherford had developed a new model:

Answer 5

-Atoms have a central nucleus
-Most of the mass of an atom is in its nucleus
-The nucleus is positively charged
-A nucleus is surrounded by empty space in which electrons move

Question 6

What observations have Rutherford’s new model explained?

Answer 6

-The positive particles that bounced back had hit a nucleus
-The positive particles that went straight through the foil had passed through the empty space between nuclei.

Question 7

Scientist James Chadwick investigate nucleus:

Answer 7

In 1932, he developed a new model of atom:
-Positive protons and neutral neutrons in the nucleus
-Negative electrons orbiting outside the nucleus