P6

Question 1

Definition of an isotope

Answer 1

and isotope is an atom of the same element with different mass number due to more/less neutrons

Question 2

What happens in isotope of an element is unstable?

Answer 2

One isotope of an element is unstable it is radioactive and will give out nuclear radiation decay into other elements

Question 3

What is an alpha particle ?

Answer 3

An alpha particle is a big heavy and slow moving particle given out during Alpha radiation which is 2 neutrons and two protons giving a relative mass of four and a charge +2.

Question 4

What is Alpha radiation blocked by?

Answer 4

Alpha radiation is blocked by a sheet of paper

Question 5

Write the equation for the Alpha radiation of radium

Relative atomic mass of 226

Answer 5

Radium has a mass of 226 and a atomic number of 88. As an alpha particle contains two protons the atomic number will drop by 2 making it decay into radon and the mass number will drop by four

(226, 88) Ra–> (222, 86) Rn + (4,2) alpha particle

Question 6

What is a beta particle ?

Answer 6

A beta particle is particle given out during beta radiation of an element it is a small and fast particle made up of a single electron with no mass and a charge of -1 . During beta decay for every beta particles
emitted a neutron turns to proton.

Question 7

Which material blocks beta radiation ?

Answer 7

Thin aluminium stops beta radiation

Question 8

Write down the equation 4 the beta radiation of carbon

Answer 8

The mass does not change but the atomic number increases by one as there is one more proton because for every beta particle emitted a neutron turns to a proton so it decays into nitrogen

(14,6) C –> (14,7) N + (0,-1) beta

Question 9

What is gamma radiation?

Answer 9

Gamma radiation is the extra energy given off by a particle after spitting out an alpha or beta particle the type of electromagnetic wave with no mass and no charge.

Question 10

What is gamma radiation blocked by ?

Answer 10

Gamma radiation is blocked by thick laead

Question 11

What is count rate?

Answer 11

Count rate is the number radioactive particles that reach a detector any given time the further the radiation has to travel the higher the chance it will be absorbed by the material which is travelling through this means the count rate decreases a further the detector is from a radioactive source .

Question 12

What is an excited electron and how can an electron become excited ?

Answer 12

An excited electron is an electron that as a result enough em. radiation to get enough energy to become excited and moved to the next energy level . The electron will then fall back down an energy level and the energy will be lost and carried away by EM radiation.

Question 13

What is ionisation

Answer 13

ionisation is when the outer electron absorbs enough energy from EN radiation that you can leave the atom and become ionised . The atom is now a positive ion.

Question 14

Give three types of radiation that can ionise atoms

Answer 14

alpha, beta and gamma radiation can ionise atoms .

Question 15

Which particles out of Alpha beta and gamma have the highest ionisation power on what does this mean?

Answer 15

Alpha particles have the highest ionisation power meaning they can’t travel very far through a substance without hitting an atom and ionizing it.

Question 16

Explain in terms of excited electrons have fluorescent tubes work

Answer 16

1) electrons accelerated through mercury vapour which ionises the mercury atoms producing free electrons
2) the flow of free electrons collide with the mercury atoms exciting them to higher energy levels
3) when excited electrons lose their energy and fall back down they emit ultraviolet radiation
4) the UV radiation is absorbed by phosphorus coating inside the tube
5) finally the electrons inside the phosphorus coating are excited due to the UV energy and when they fall they emit visible light

Question 17

Why can’t scientist tell when individual nuclei are going to decay?

Answer 17

Scientists cannot predict when individual nuclei will decay because radioactive decay is a random process

Question 18

What is a half life?

Answer 18

Half life is the time taken for the activity (count rate)/Number of nuclei of a radioactive isotope to half

Question 19

What is the count rate?

Answer 19

Camera is number accounts per second recorded by Geiger-Müller tube in becquerels (Bq)

Question 20

What is irradiation?

Answer 20

Irradiation is exposing object to nuclear radiation

Question 21

What is irradiation risk?

Answer 21

Irradiation risk is how likely an object will be irradiated by a source. Alpha has a lower irradiation risk due to its lower range

Question 22

What is contamination?

Answer 22

Contamination is when I wanted radioactive isotopes and up on other materials

Question 23

What are the risks of radiation to human biology?

Answer 23

• Low doses of ionising radiation damage cells by causing mutations in the DNA which causes cells to divide uncontrollably which is cancer
• High doses of ionising radiation can kill cells which can cause radiation sickness

Question 24

Which types of radiation and most dangerous outside the body

Answer 24

Beta and gamma radiation the most dangerous outside the body because they can pass through the skin to sensitive organs. Alpha cannot penetrate the skin

Question 25

Which types of radiation and most dangerous inside the body

Answer 25

Alpha radiation is most dangerous inside the body because it’s the most ionising and does all of its damage in a local area. Beta and gamma are less dangerous because they are less ionising And more likely to pass straight out

Question 26

Are sources with long or short half lives more dangerous?

Answer 26

Sources with long half lives are more dangerous because they won’t decay quickly and remain hazardous for a long time

Question 27

How is radiation used in medical tracers?

Answer 27

Gamma emitting substances with short half lives can be injected/ ingested and followed using a radiation detector as they pass around the body to see how parts of the body are working

Question 28

How can radiation be used in externally treating cancer?

Answer 28

Gamma rays are focused on the tumour and rotated round using a wide beam to try and kill cancer cells. It’s given in doses to allow healthy cells to be repaired/ replaced

Question 29

How can radiation be used to treat cancer internally?

Answer 29

Implants containing beta emitters can be placed next to or inside a tumour to damage cells. The damage to healthy cells is limited due to its short range. The implant can either have a short half life and be left in or a long half life and be removed.
Alpha emitters can also be injected into tumours which do great damage as they are strangely ionising. They also limit damage further due to a really short range

Question 30

Explain what happens during nuclear fission

Answer 30

1) nuclear fission occurs in large unstable nuclei either spontaneously or as a result of absorbing a neutron
2) it splits into two smaller daughter nuclei of equal size, releases gamma radiation and two or three neutrons
3) the neutrons then go on to be absorbed into other nuclei causes fission to occur again which sets off a chain reaction

Question 31

Why is nuclear fission useful?

Answer 31

Nuclear fission is useful in generating electricity in nuclear power stations. A controlled fission chain reaction takes place which is used to heat water to produce steam. The steam drives a steam turbine which is connected to an electric generator

Question 32

What are the problems with nuclear power plants?

Answer 32

Problems with nuclear power plants include the nuclear waste produced, the high cost of running, the risk of leak and risk of a catastrophe like at Chernobyl

Question 33

What is nuclear fusion?

Answer 33

Nuclear fission is when two light nuclei such as hydrogen are joined to form a heavier nucleus. Some mass is converted to energy lending huge amounts of energy is given out

Question 34

Why could nuclear fusion be useful?

Answer 34

Nuclear fusion has the potential to be used in fusion reactors to generate electricity in the future. It also doesn’t create radioactive waste and there’s plenty of hydrogen for fuel.

Question 35

What are the problems with fusion reactors.

Answer 35

Fusion needs an extremely high temperature to happen (10000000 degrees), it needs a high pressure and it needs an extreme strong magnetic field