P7: Radioactivity

Question 1

What is the radius of an atom?

Answer 1

1 x 10^-10 meters

Question 2

What is count-rate?

Answer 2

The number of decays recorded each second by a detector

Question 3

What is an alpha particle?

Answer 3

2 neutrons and 2 protons which is the same as helium

Question 4

What is a beta particle?

Answer 4

A high speed electron ejected from the nucleus as a neutron turns into a proton

Question 5

What is a gamma particle?

Answer 5

Electromagnetic radiation from the nucleus

Question 6

What is a half-life?

Answer 6

The time it takes for the number of

Question 7

What is radioactive contamination?

Answer 7

The unwanted presence of materials containing radioactive atoms on other materials

Question 8

What is irradiation?

Answer 8

The exposing an object to nuclear radiation, and the irradiated object does not become radioactive

Question 9

Where does background radiation come from?

Answer 9

Either natural sources like rocks and cosmic rays, or man made sources like fallout from nuclear weapon testing and nuclear accidents

Question 10

How are nuclear radiations used in medicine?

Answer 10

Exploration of internal organs and control or destruction of unwanted tissue

Question 11

Describe the process of fission

Answer 11

Nucleus is split into 2 smaller nuclei, and emits 2 or 3 neutrons plus gamma rays.

Question 12

How is a chain reaction controlled?

Answer 12

In a nuclear reactor to control energy released.

Question 13

What causes an explosion in a nuclear weapon?

Answer 13

Uncontrolled chain reaction

Question 14

What is the source of a beta particle?

Answer 14

A neutron decaying into a proton and an electron

Question 15

What determines how harmful radiation is?

Answer 15

Type of radiation, where you’re exposed and the amount you receive

Question 16

How can irradiation be minimsed?

Answer 16

Wear protective gear, keeping item in lead-lined box and handle with tongs

Question 17

What factors affect the amount of radiation you receive?

Answer 17

How long you’re exposed to the substance, how radioactive it is and how far away from the source you are

Question 18

What are 2 ways radiation can treat cancer?

Answer 18

Gamma rays are emitted to cancer and internally, by placing radioactive source near cancer source and uses beta radiation

Question 19

Evaluate the use of medical tracers and radiotherapy for treatment

Answer 19

Medical tracers help diagnoses, so worth the risk, however low doses and ones with a short half-life are needed to minimise risk. Radiotherapy can save a person’s life, but it only extends life for a short period.

Question 20

What are side effects of radiotherapy?

Answer 20

Healthy cells will be killed, making the patient ill

Question 21

What are the pros of nuclear energy?

Answer 21

Uranium and plutonium is relatively cheap, produces a large and steady amount of energy and does not release greenhouse gases

Question 22

What are the cons of nuclear energy?

Answer 22

Power plants are expensive to build, nuclear waste is expensive to get rid of and there is a risk of major disaster

Question 23

What is the process that fuels stars?

Answer 23

Nuclear fusion

Question 24

Why does fusion release tons of energy?

Answer 24

Because the mass of original nuclei is being converted to energy

Question 25

Why does nuclear fusion only happen in stars?

Answer 25

Because of the high temperatures and pressures that are required

Question 26

Why does fusion only happen at very high temperatures and pressures?

Answer 26

To overcome the repulsion of positively charged nuclei