CP6

Question 1

Diameter of an atom

Answer 1

10^-10m

Question 2

Diameter of nucleus

Answer 2

10^-15m

Question 3

Electron movement

Answer 3

• Electrons orbit the nucleus in different orbits of energy leaves
• An electron will move from a lower to a higher orbit if it absorbs electromagnetic radiation
• An electron will move from a higher to a lower orbit if it emits electromagnetic radiation

Question 4

Ionizing radiation

Answer 4

Alpha, beta, gamma and neutron radiation are emitted by unstable nuclei

Question 5

Alpha particles

Answer 5

Will travel 5cm in air
Very ionizing
Can be stopped by a piece of paper

Question 6

Beta particles

Answer 6

Will travel a few meters in air
Moderately ionizing
Can be stopped by aluminum

Question 7

Gamma rays

Answer 7

Will travel a few km in air
Weak ionizing
Need thick lead to stop them

Question 8

Background radiation

Answer 8

low levels of radiation that are present all the time. Both natural and man made.

Question 9

Measuring radioactivity

Answer 9

Geiger-muller tube detects nuclear radiation. It is connected to a counter which shows the amount of radiation that has been detected

Question 10

Beta decay

Answer 10

When unstable nuclei undergo radioactive decay (there are two types- one where an electron is admitted and one where a positron is emitted)

Question 11

Beta-minus decay

Answer 11

A neutron decays to become a proton and an electron. The proton stays with the nucleus but the electron is emitted at a high speed.

Question 12

Beta-plus decay

Answer 12

A proton decays to become a neutron and a positron. The neutron stays in the nucleus and the positron is emitted at a very high speed carrying a positive charge

Question 13

Uses of beta decay

Answer 13

Carbon-14 is used for radiocarbon dating which finds the ages of materials that are very old.

Question 14

Half life

Answer 14

The time it takes for half of the unstable atoms to decay

Question 15

Uses of gamma rays

Answer 15

• Killing cancer cells

- Sterilise hospital equipment

Question 16

Use of alpha particles

Answer 16

• Smoke alarms

Question 17

Danger of radiation

Answer 17

Ionizing radiation can knock electrons out of atoms, turning them into ions. This can be very damaging to humans

Question 18

Radiation precautions

Answer 18

• Limiting the time of exposure to radiation
• Wearing protective clothing that absorbs radiation
• Increasing the distance between the person and the source of radiation

Question 19

Irradiation

Answer 19

Irradiation is ionizing radiation from an external radioactive source traveling to the body (it is not breathed in, eaten or drunk)

Question 20

External Contamination

Answer 20

Occurs when radioactive materials come in contact with a persons hair, skin or clothing

Question 21

Internal Contamination

Answer 21

Occurs when a radioactive source is eaten or drunk

Question 22

Medical uses of ionizing radiation

Answer 22

• Tracers
• PET scanners
• Treating tumors internally
• Treating tumors externally

Question 23

Medical traces

Answer 23

• Substances that contain radioisotopes
• The radiation emitted by the tracer can be detected and the biological process monitored
• Doctors can diagnose the nature and the location of any health problems

Question 24

Treating tumors internally

Answer 24

• Radioisotopes are injected/ are injected by eating or drinking
• The radiation emitted kills cancer cells

Question 25

Treating tumors externally-

Answer 25

• Beams of gamma rays are fired from different angles towards the cancer
• Each beam is not damaging enough to kill it, but damages it
• The amount of ionizing radiation that the surrounding tissue receives is reduced

Question 26

Nuclear power

Answer 26

Nuclear power is a highly efficient way of producing electrical energy. However nuclear power stations do produce a lot of radioactive waste that has to be dealt with.

Question 27

Eval of nuclear power

Answer 27

:) Does not produce carbon dioxide
:) Supplies of carbon dioxide will last longer than fossil fuels

:( Difficult and expensive to store safely
:( An accident in a nuclear power station can spread radioactive material over a large area

Question 28

Nuclear fusion

Answer 28

Nucleus fusion involves the joining of smaller nuclei to form larger nuclei. Nuclei need to get very close together for fusion to happen. Under normal conditions, nuclei repell eachother. Very high temperatures and pressures are required to overcome this electrostatic repulsion.

Question 29

Nuclear fission

Answer 29

In a fission reaction, a large unstable nucleus splits into two smaller ones (e.g a uranium-235 nucleus splits up when it absorbs a neutron. It produces two daughter nuclei, two or more neutrons and releases energy)

Question 30

Chain reactions

Answer 30

The neutrons released by the fission of U-235 may be absorbed by other nuclei. Each of these may undergo fission and produce even more. This is called a chain reaction If a chain reaction is not controlled there will be an explosion.