H220 Nuclear Physics

Question 1

What are the deductions from majority of alpha particles going straight through / deviated by small angles less than 10 degrees in the Rutherford a-scattering experiment.

Answer 1

1. Most of atom is empty space and the mass of atom is concentrated in a very small nucleus (size of atom 10^-10m, size of nucleus 10^-15)
2. Nucleus is positively charged, hence majority of alpha particles pass through atoms far enough from nucleus to experience negligible electrostatic repulsion.

Question 2

What is the deduction from a small proportion of the alpha particles deflected through large angles of more than 90 degrees / came straight back in the Rutherford a-scattering experiment.

Answer 2

A small number of alpha particles that come close enough to the positively charged nucleus experienced significant electrostatic repulsion and are deflected through large angles.

Question 3

What has the Rutherford alpha scattering experiment established?

Answer 3

The presence of a massive, positively charged nucleus that occupies a tiny fraction of the volume of an atom.

Question 4

Define mass defect.

Answer 4

Mass defect of a nucleus is the difference between the total mass of individual, free nucleons and the mass of the nucleus.

Question 5

What is the formula for mass defect?

Answer 5

Mass defect =