Radioactivity and Particles

Question 1

Name the particles that made up atom and state their electrical charges

Answer 1

-Proton:+
-Neutron:=
-Electron:-

Question 2

What is an isotope

Answer 2

Same element with same amount of protons but with a different number of neutrons

Question 3

Why is an atom neutral?

Answer 3

-An atom contains the same number of protons and electrons
-Charge of the proton is +1 and the charge of electron is -1
-The charges balance, so the atom has no overall charge

Question 4

What types of radiation are emitted from unstable nuclei

Answer 4

-Alpha particles
-Beta partices
-Gamma rays
-Neutron radiation

Question 5

Types of ionising radiation

Answer 5

-Alpha
-Beta
-Gamma

Question 6

What is meant by background radiation

Answer 6

-Radiation that is always around
-It is in very small amounts and so not harmful

Question 7

Describe sources of background radiation

Answer 7

-Unstable nuclei in rocks
-Raiation used in medicine
-Some is released from food and water
-Living things (plants absorb radioactive material as they grow and this can be passed on to the animals that eat them).
-Cosmic rays from the sun

Question 8

State two pieces of equipment and describe them that can be used to detect radiation

Answer 8

-Geiger-Müller Detector: absorbs radiation and produces a pulse. The frequency of the pulse depends on how much radiation is present. A high frequency would mean the tube is absorbing a large amount of radiation
-Photographic film: Turns dark when it absorbs radiation. This is useful for the people who work on radiation as the more radiation they are exposed to, the darker the film becomes. Therefore the workers know when they were exposed to too much radiation

Question 9

Order the types of ionising radiations starting with the least ionising

Answer 9

Gamma→Beta→Alpha

Question 10

What is a beta particle?

Answer 10

An electron

Question 10

What is an alpha particle?

Answer 10

A helium nucleus (2 neutrons and 2 protons)

Question 11

What is a gamma ray?

Answer 11

High energy carrying electromagnetic wave from the electromagnetic spectrum

Question 12

Describe beta decay

Answer 12

Process in which a neutron splits into a proton and an electron is emmited from the nucleus

Question 13

When alpha decay occurs, what happens to the atomic number and the mass number of the atom?

Answer 13

Atomic number decreases by 2 and the mass number decreases by 4

Question 14

What effect does beta decay have on the mass number and atomic number of an atom

Answer 14

-The mass number stays the same as the combined number of neutrons and protons hasn’t changed
-The atomic number increases since there’s one more eproton

Question 15

What happens in the atom to cause gamma rays to be released?

Answer 15

The nucleus decays some of the neclei rearranges itself so there is an excess energy.

Question 16

How does the activity of a radioactive source decreases over a period of time?

Answer 16

-Decreases exponentially
-Decreases by a constant ration over constant time periods

Question 17

Define half life

Answer 17

The time taken for a source half of its initial mass to decay

Question 18

What is the unit for activity

Answer 18

Becquerel

Question 19

Can you predict when a nucleus will decay?

Answer 19

No, the process is random

Question 20

Give examples of uses of radioactivity

Answer 20

-Household fire alarms
-Irridiating food
-Sterilisation of equipment
-Tracing a gauging thickness of materials
-Diagnosis and treatment of cancer

Question 21

How do smoke alarms work?

Answer 21

-A radioactive substance is in the alarm which emits alpha radiation
-The emitted alpha particle ionise the air in the detector and causes a current to flow between the plates
-When smoke interfered with radiation, the air is no longer ionised and so no current can flow
-This reduction in current flow triggers the alarm

Question 22

How is radiation used in medicine?

Answer 22

-To sterilise equipment: Gamma radiation can kill bacteria cells
-To help treat cancer, as it can be used to kill cancer cells.

Question 23

What was the role of beta radiation in tracers

Answer 23

-The tracer is inserted in your body, and targets a specific part of the body
-The radioactive substance in the tracer releases beta radiation which can be detected by external machines

Question 24

How is beta radiation used to determine thickness?

Answer 24

-A beta source is placed above the material and a detector is placed below it
-If a lot of radiation is detected by the detector, too much radiation is passing through the material and so it is too thin
-If only a little radiation is detected, then the material blocks too much radiation, and so its too thick

Question 25

Why is ionising radiation dangerous

Answer 25

-It can damage tissue and kill cells
-It can cause cell mutations

Question 26

What precautions should people take when using ionising radiation

Answer 26

-Avoid handling the source directly
-Wear radiation protective clothing
Keep that radiation in lead contained to reduce the amount of radiation that can escape
-Avoid being exposed to the radiation for long periods of time

Question 27

Does a long half life or a short half life make a source more dangerous?

Answer 27

If it has a long half life then it would remain highly radioactive for longer therefore making it more dangerous.

Question 28

What precautions are taken to reduce harm for doctors and patients using ionising radiation?

Answer 28

-Only a small dose is given
-The radiation used has a very short half life
-Medical staff also weards protective clothing

Question 29

What is the difference between contamination and irradiation?

Answer 29

-Contamination is when radioactive substances are transferred to objects through processes such as touching the source or breathing it in
-Irradiation is when the object comes in contact with the radioactive source. The source doesn’t actually enter your body and the radiation will stop if you move away from the area.

Question 30

You can treat tumors internally or externally. Evaluate this two methods

Answer 30

Internal- uses a tracer and can use alpha radiation, which is poorly penetrating and cannot reach the healthy cells
External- concentrated the beam on specific parts of the body. For the external method a long half life is required so it doesn’t remain in the body for too long

Question 31

What is a radioactive tracer used for in medicine?

Answer 31

-Tracer placed inside the body
-Tracer releases gamma radiation which is detected by a detector which moves around the body
-This can then be used to produce a picture of the patient’s body

Question 32

Describe the advantages of nuclear power for generating electricity

Answer 32

-Nuclear fuels do not produce carbon dioxide
-The fuel is readily available, meaning it would reduce the pressure of the fossil fuels.
-Less nuclear fuel has to be used to produce the same amount of energy as burning fossil fuel
-Does not contribute to global warming

Question 33

Describe the disadvantages of nuclear power for generating electricity

Answer 33

-Perceived as dangerous
-Security risks as the radioactive substances can be useful for terrorists
-A lot of money and time is requires to commission and decommission stations-may be bad for a country’s economy
-Radioactive waste can be difficult to dispose and will remain radioactive for many years
-Workers have to get checked regularly
-Can cause widespread disasters such as chernobyl

Question 34

Explain the process of fission of U-235

Answer 34

Absorbs a neutron which makes it unstable. This causes it to split into two daughter nuclei and release two or more neutrons as well as releasing energy.

Question 35

Why do we refer to the reactions in a nuclear power station as a controlled chain reaction?

Answer 35

-Neutrons released are absorbed by another nuclei, causing the other nuclei to also undergo fission, releasing further neutrons
-It is controlled by a control rod which absorbs excess neutrons

Question 36

What is the job of a moderator?

Answer 36

It slows down the neutrons until they are travelling at a speed slow enough for them to be absorbed

Question 37

How are control rods used to ensure a controlled reaction?

Answer 37

-They are raised or lowered so that they absorb fewer or greater neutrons
-The number of neutrons that they absorb determines how many reaction can take place

Question 38

Explain how electricity is produces in a nuclear power station

Answer 38

-The reactions release thermal energy
-This energy is used to boil water and then produce steam
-This steam is then used to turn a turbine which starts the generator

Question 39

What is nuclear fusion?

Answer 39

When two small nuclei fuse together to form a larger nuclei. This process releases energy

Question 40

Where does fusion occur everyday?

Answer 40

In the sun- stars use fusion as their energy source

Question 41

Why can’t nuclear fusion be used as our energy source?

Answer 41

-On earth we cant get high temperatures and pressures for nuclear fusion to happen, whilst still being cost effective
-This is because both nuclei are positive therefor a lot of energy is required to overcome the electrostatic repulsion between the two nuclei.

Question 42

Why is fission currently used instead of fusion?

Answer 42

-Fission can be used for nuclear power is easily controlled, whereas fusion is harder to control
-Fusion requires very harsh conditions, whereas fission does not