Chapter 7 -Atomic Structure and radiation

Question 1

what is activity rate?

Answer 1

Activity is the rate at which a source of unstable nuclei decays

• So a sample with high activity has a fast rate of decay
• Measured in Becquerel, Bq

NUMBER OF UNSTABLE AYTOMS THAT DECAY PER SECOND IN A RADIOACTIVE SOURCE

Question 2

what is half life?

Answer 2

The half-life of an isotope is the time taken for half the nuclei in a sample to decay or the
time taken for the activity or count rate of a sample to decay by half.

Question 3

Why would the alpha particles be deflected by a smaller angle if the thin metal foil was made of a lighter element?

Answer 3

The nuclei of lighter elements contain fewer protons. This means they have a lower charge. Each alpha particle will, therefore, experience a smaller electric force acting on it and so deflect by a smaller angle.

Question 4

what is an ion?

Answer 4

Ions are charged particles that form when an atom either loses or gains electrons.

Question 5

alpha characteristics

Answer 5

highly ionising
weakly penetrating
travels 5 cm of air