Atomic And Nuclear Physics

Question 1

What is the structure of the atom?

Answer 1

An atom consists of a nucleus that contains positive protons and neutral neutrons. Negative electrons orbit this nucleus in shells

Question 2

What was the Rutherford alpha particle experiment?

Answer 2

. To try and prove the plum pudding model created by JJ Thompson, Ernest Rutherford, devised an experiment which fired positively charged alpha particles at a thin piece of gold foil.
. The observations from this experiment were:
- Most of the alpha particles went straight through the foil
- A few alpha particles were slightly deflected
- Some were deflected through very large angles
- 1 in 8000 were reflected directly back in the direction they came
. These observations could not be explained by the plum pudding model

Question 3

What is radioactive decay?

Answer 3

The process in which a radioactive atom spontaneously gives off radiation in the form of energy or particles to reach a more stable state

A = - dN / dt

• Not finished

Question 4

What is radioactive background activity?

Answer 4

• Natural sources of radiation such as cosmic rays from space or from rocks and soil.
• Radioactive material is found naturally all around us.
• All these natural sources are known as background radiation.

Question 5

What is half-life?

Answer 5

• The time taken for a radioactive material for its activity to fall to half of its original value.
• For example, if there are 40 billion atoms present at an instant in time, and 8 days later 20 billion of these atoms have decayed, the half life would be 8 days

Question 6

What are the dangers of radioactivity?

Answer 6

• Radioactive emissions cause dangerous ionisation by removing electrons from atoms.
• When this happens with molecules in living cells, the genetic material of a cell (the DNA) is damaged. This can lead to cancer.
• Radiation can also deposit large amounts of energy into the body, which can damage or destroy cells completely.