P6.1 Radioactive emissions

Question 1

Define: activity

Answer 1

the number of decays per second

Question 2

Define: alpha (radiation)

Answer 2

a particle emitted by an unstable nucleus, a helium nucleus, very ionising but not penetrating

Question 3

Define: becquerel (Bq)

Answer 3

the unit of activity of a radioactive material, equivalent to one decay per second

Question 4

Define: beta (radiation)

Answer 4

a particle emitted by an unstable nucleus, a fast electron, not very ionising but quite penetrating

Question 5

Define: Geiger counter

Answer 5

a device for measuring the activity of a radioactive material

Question 6

Define: half-life

Answer 6

the time it takes for half the unstable nuclei to decay, or for the activity to halve

Question 7

Define: ionising radiation

Answer 7

particles or waves that can completely remove an electron from an atom

Question 8

Define: isotope (of an element)

Answer 8

atoms with the same number of protons and electrons, but different numbers of neutrons, are isotopes of the same element

Question 9

Define: mass number

Answer 9

the number of protons and neutrons in the nucleus of an atom

Question 10

Define: penetrating power

Answer 10

the ability of radiation to travel through a material (e.g. air, metal), which is linked to ionisation

Question 11

Define: radioactive

Answer 11

a material containing unstable nuclei that emit radiation

Question 12

Define: random radioactive decay

Answer 12

the nature of radioactive decay as each nucleus has a fixed probability of decay

Question 13

Define: unstable (nucleus)

Answer 13

a nucleus that decays by emitting radiation or splitting (fission)