GCSE Physics 1:4

What are the two main types of isotopes?

Stable and unstable

What makes an isotope unstable (brief)?

They undergo nuclear decay

What is nuclear decay? What does this mean for research?

When an unstable radioctive isotope changes in some way by emitting something to make itself more stable—many of them are extremely difficult to study

What are unstable isotopes also known as?

Radioactive, radioisotopes

What is radioactivity?

The spontaneous radioactive decay of an unstable atomic nucleus

What is activity?

The rate at which nuclei decay

What is activity measured in? What does this represent?

Bequerel (Bq)—decays per second

What is count rate?

The number of decays recorded each second by a detector, such as a Geiger-Muller tube and counter (Geiger counter)

What is count rate measured in?

Counts per second (cps)

What is the difference between activity and count rate?

Activity is an intrinsic property of the material itself—count rate depends on external factors, such as distance, efficiency and background radiation

Why will there always be some uncertainty in the number of decays in a given time?

Radioactive decay is a random process

Why does radiation release heat?

The kinetic energy from the subatomic particles emitted due to radiation is converted to thermal energy, as these particles collide with their surroundings

What are the 3 key types of radiation?

Alpha ($\alpha$ ), Beta ($\beta$ ), Gamma ($\gamma$ )