Radioactivity

Question 1

What is the relative mass and charge of protons?

Answer 1

relative mass of 1 and a relative charge of +1

Question 2

What is the relative mass and charge of neutrons?

Answer 2

Relative mass of 1 and a relative charge of 0

Question 3

Where are electrons located in an atom?

Answer 3

In shells (energy levels) surrounding the nucleus

Electrons play a crucial role in chemical bonding and interactions.

Question 4

What is the relative mass and charge of electrons?

Answer 4

Relative mass of 1/1840 and a relative charge of -1

Question 5

How is the mass number of an atom calculated?

Answer 5

Mass number = number of protons + number of neutrons

Question 6

What does the atomic number represent?

Answer 6

The number of protons in an atom

Question 7

What is the significance of electrons in relation to mass number?

Answer 7

Electrons do not contribute to the mass number

Question 8

What does background radiation consist of?

Answer 8

• inhaled radon gas
• rocks and soil
• cosmic rays
• human activity / medical imaging
• food and drink

Question 9

How can a Geiger-Muller tube measure background radiation?

Answer 9

By counting the number of ‘beeps’ per minute, without a radioactive source in front of it

Question 10

What type of damage can radiation cause to DNA?

Answer 10

It can ionise the atoms, ripping off their electrons and potentially causing mutations

Question 11

What are the potential consequences of a damaged gamete cell due to radiation?

Answer 11

The foetus’ cells will have a mutated DNA segment

Question 12

What can radiation damage aside from DNA?

Answer 12

Cell membranes and can even kill cells. This can lead to radiation burns or organ failure.

Question 13

Why does radioactive waste need to be stored under very specific conditions?

Answer 13

Because it has a very long half-life, and could still be ionising

Question 14

What are the three types of ionising radiation?

Answer 14

Alpha, beta, and gamma

Question 15

What is an alpha particle composed of?

Answer 15

2 protons and 2 neutrons

An alpha particle is essentially a helium nucleus.

Question 16

What charge does an alpha particle have?

Answer 16

Double positive charge

Question 17

How does alpha radiation compare in terms of penetration?

Answer 17

Low penetration. It is stopped by just a sheet of paper

Question 18

What is a beta particle?

Answer 18

A fast moving electron

Question 19

How is a beta particle produced?

Answer 19

When a neutron decays into a proton, releasing an electron.

Question 20

What is the penetration ability of beta radiation?

Answer 20

Easily passes through air, stopped by a few mm of low density metal, like aluminium

Question 21

What are gamma rays?

Answer 21

Electromagnetic waves with no mass or charge

Question 22

How penetrating are gamma rays?

Answer 22

Stopped by several centimetres of lead or several metres of concrete

Question 23

Rank the types of radiation from most ionising to least ionising

Answer 23

Alpha, Beta, Gamma

Question 24

What is Alpha decay?

Answer 24

Loss of two protons and two neutrons from the nucleus, releasing an alpha particle

Question 25

What occurs during Beta decay?

Answer 25

Transformation of a neutron into one proton and one electron, which gets released

Question 26

What is gamma decay?

Answer 26

The atomic and mass numbers are unchanged, as gamma has no mass or charge, but the nucleus transitions from a high energy state to a lower energy state

Question 27

What is Neutron decay?

Answer 27

A neutron has no charge and a mass of 1 so only the mass number changes, not the atomic number.

Question 28

What does the Law of conservation of mass state?

Answer 28

Initial mass number = final mass number, initial atomic number = final atomic number

Question 29

What does the Law of conservation of charge state?

Answer 29

Initial total charges = final total charge

Question 30

What is the activity of a radioactive sample?

Answer 30

The number of parent nuclei that decay per second

Question 31

What is the unit for activity?

Answer 31

The unit of activity is Bequerel (Bq), which is equivalent to one decay per second.

Question 32

What is the formula for calculating activity?

Answer 32

Activity = total number of decays / time taken

Question 33

What does a Geiger counter measure?

Answer 33

The number of detected ionising particles per second ## Footnote The count rate is calculated as total counts / time taken (s).

Question 34

Is it possible to tell when a particular nucleus will decay?

Answer 34

No, this process is random. However, it is possible to predict the number of decays in a certain time.

Question 35

What is half-life?

Answer 35

The time taken for the activity of a sample to halve OR the time it takes for half of the unstable nuclei to decay.

Question 36

What are the agricultural uses of radioactive materials?

Answer 36

Understanding chemical and biological processes in plants. You can use them in chemical reactions so you can tell what the plant uses that element for.

Question 37

What is the purpose of radioactive isotopes in medical imaging?

Answer 37

To create images of the body's organs by detecting emissions from the isotopes

Question 38

Why do you use a radioisotope with a relatively short half-life (6 hours) in medical imaging?

Answer 38

Because it is long enough to draw conclusions from the data, but short enough that the patient isn't exposed to unneccecary radiation

Question 39

What is food irradiation?

Answer 39

Using radioactive sources to treat food for safety and preservation

Question 40

Does food become radioactive after irradiation?

Answer 40

No, the food never comes into contact with the radioisotope

Question 41

How is radioactive sterilisation useful in medicine?

Answer 41

To sterilize scalpels and other equipment instead of using chemicals or high temperatures.

Question 42

What does teletherapy do in radiotherapy?

Answer 42

It kills both cancer cells and healthy cells by bombarding them with gamma rays.

Question 43

What is brachytherapy?

Answer 43

Injecting a beta emitter directly into the tumor

Question 44

What is carbon dating used for?

Answer 44

To discover when an organism died by measuring the amount of carbon-14 in it.

Question 45

What is fission?

Answer 45

The process where a large nucleus, like U-235, is bombarded by a slow-moving neutron, becoming unstable and splitting into two smaller, radioactive nuclei and three neutrons, releasing energy. These neutrons go on to bombard further U-235 nuclei.

Question 46

What role do control rods play in a fission reactor?

Answer 46

They absorb excess neutrons to prevent uncontrollable reactions.

Question 47

What is the purpose of moderators in a fission reactor?

Answer 47

To slow down neutrons so fission can continue occurring.

Question 48

List the main components of a fission reactor.

Answer 48

* Fuel (contains uranium-235) * Moderator * Control rods * Coolant * Cooling tower * Pumps * Generator * Condenser

Question 49

What is the function of coolant in a fission reactor?

Answer 49

It lessens the risk of radiation leaks.

Question 50

How does gauging work?

Answer 50

Radiation from a source has reduced intensity of there is matter in between the source and detector. This can be used to measure the thickness of that matter

Question 51

What is fusion?

Answer 51

When two lighter nuclei are combined to make a heavier one.

Question 52

What happens to mass during the fusion process?

Answer 52

There is a loss of mass as energy is released.

Question 53

Where does fusion occur naturally?

Answer 53

Fusion occurs in the sun and other stars.

Question 54

What conditions are required for fusion to happen?

Answer 54

Intense heat and pressure are required to overcome the magnetic repulsion of the two positive nuclei. This is why it is not possible to have fusion reactors on earth (yet)