Radioactivity

Question 1

What is a radioactive substance?

Answer 1

a substance containing unstable nuclei that become stable by emitting nuclei

Question 2

What types of radiation can be given out by a radioactive substance? (list in order of penetration)

Answer 2

• Alpha radiation
• Beta radiation
• Gamma radiation

Question 3

Who discovered radiation?

Answer 3

Marie Curie

Question 4

How penetrating is alpha radiation?

Answer 4

• stopped by paper
• has a travel distance of a few centre meters in air
• two protons and two neutrons

Question 5

we say a nucleus decays when it does what?

Answer 5

emits radiation

Question 6

radioactive decay is

Answer 6

random, we can’t influence it or predict when it will happen.

Question 7

where is background radiation from?

Answer 7

• radioactive substances in space or the environment

- devices like x-rays

Question 8

How was the model of the nucleus formed?

Answer 8

Rutherford used measurements from alpha scattering experiments to prove that there was small positively charged mass in the centre of the atom

Question 9

What could the plumb pudding explain?

Answer 9

why some alpha particles scattered at large angles

Question 10

what is an isotope?

Answer 10

elements with the same number of protons but different numbers of neutrons

Question 11

list two changes in the nucleus for Alpha particles decay

Answer 11

Nucleus losses:

• 2 protons
• 2 Neutrons

Question 12

list changes in the nucleus for Beta particles

Answer 12

A neutron changes into a proton

Question 13

list the properties of beta radiation

Answer 13

• stopped by thin metal
• a range of 1 meter in air
• fast moving electrons emitted from nucleus

Question 14

a magnetic field can be used to do what?

Answer 14

separate a beam of alpha, beta and gamma radiation

Question 15

list the properties of gamma radiation

Answer 15

• stopped by thick lead
• has an infinite range in air
• consists of electromagnetic radiation

Question 16

what can ionisation cause?

Answer 16

killing or damaging a living cell

Question 17

what does the term half life mean?

Answer 17

the average time it takes of a radioactive isotope to half it’s nuclei (hence the half)

Question 18

the activity of a radioactive source is known as what?

Answer 18

the number of nuclei that decay per second

Question 19

how do we choose a radioactive isotype for its job?

Answer 19

we take into account:

• it’s half life
• the type of radiation it gives out

Question 20

radio active tracers should be what?

Answer 20

• beta or gamma

- last long enough to be monitored