Radioactivity and particles

Question 1

What type of process is radioactive decay?

Answer 1

A random process

Question 2

What breaks down during radioactive decay?

Answer 2

The nuclei of unstable isotopes

Question 3

What does nuclear radiation cause and how?

Answer 3

Ionisation by bashing into atoms and knocking electrons off them. The atoms are then turned into ions.

Question 4

How can you detect ionising radiation?

Answer 4

With a Geiger - Muller detector or photographic film.

Question 5

What are Alpha particles made up of?

Answer 5

2 protons and 2 neutrons - A helium Nuclei

Question 6

How far can alpha particles penetrate?

Answer 6

Not far because they are heavy, big and slow moving.

Question 7

Are alpha particles strongly or weakly ionising?

Answer 7

Strongly ionising

Question 8

Due to their electric charge, what happens to alpha particles?

Answer 8

They are deflected by electric and magnetic fields.

Question 9

What are beta particles?

Answer 9

electrons which have been emitted from the nucleus of an atom.

Question 10

When are beta particles emitted ?

Answer 10

When a neutron turns into a proton and an electron.

Question 11

What does emitting an alpha particle do to the nucleus?

Answer 11

Decreases the atomic number by 2 and mass number by 4.

Question 12

What happens when a beta particle is emitted?

Answer 12

The number of protons in the nucleus increases by 1 ( and therefore so does the atomic number).
The mass number stays the same.

Question 13

How far do beta particles penetrate?

Answer 13

Moderately far

Question 14

How ionising are beta particles?

Answer 14

Moderately ionising

Question 15

Due to negative charge, what happens to beta particles?

Answer 15

deflected by electric and magnetic fields.

Question 16

What are Gamma Rays?

Answer 16

Gamma rays are EM waves with very short wavelengths. They are no mass and just energy.

Question 17

How penetrative are Gamma Rays?

Answer 17

Extremely penetrative

Question 18

How ionising are Gamma Rays?

Answer 18

Weakly ionising

Question 19

Due to Gamma rays having no charge, what happens to them?

Answer 19

They are not deflected by electric or magnetic fields.

Question 20

What doe Gamma Rays do to the isotope?

Answer 20

Nothing, they have no effect on the isotope due to them being just energy.

Question 21

When are gamma rays emitted?

Answer 21

After alpha or beta radiation, or when a nucleus has excess energy.

Question 22

What do Geiger Muller detector detect and give?

Answer 22

Ionising radiation, they give the the count rate (number of radioactive particles reaching it per second)

Question 23

Give three ways to handle radioactive materials with care:

Answer 23

Keep source in lead - lined box when not in use.
Use long handled tongs/forceps to pick up.
keep safe distance form people and don’t point the source at anyone.

Question 24

What is meant by the term Half Life?

Answer 24

The time taken for half of the radioactive atoms currently present to decay.

Question 25

Uses of Nuclear radiation

Answer 25

medical tracers - beta or gama Cancer - ionising radiation Sterilise food & equipment - gamma leak detections (tracers) - gamma Thickness Gauge - beta radiation

Question 26

Risks of nuclear radiation

Answer 26

Damage cells & tissue Beta and gamma can penetrate skin and reach delicate organs. The radiation will collide with molecules in cells, causing ionisation and destroying them.

Question 27

What is exposure to radiation called?

Answer 27

Irradiation ( doesn't make something radioactive)

Question 28

What is it called when radioactive particles get on an object?

Answer 28

Contamination

Question 29

What is nuclear fission?

Answer 29

The splitting of an atom, which releases energy

Question 30

What do nuclear power stations use?

Answer 30

Nuclear fission chain reactions

Question 31

How is nuclear fission used?

Answer 31

When a slow moving neutron is absorbed by a uranium - 25 nucleus, the nucleus can split. Each time this happens, it spits out a small number of neutrons. These neutrons can hit other uranium - 25 nuclei, causing a chain reaction. when uranium - 25 splits, it creates two daughter nuclei, both lighter elements than uranium. These new nuclei are usually radioactive. Each nucleus splitting gives out a lot of energy ( in the kinetic stored of the fission products- the daughter nuclei and the neutrons) In a reactor, the energy is transferred to thermal energy stores to produce steam to drive a turbine.

Question 32

What is the moderator made of and what does it do in nuclear reactors?

Answer 32

graphite or water, slows down neutrons.

Question 33

What are control rods made of when what do they do in nuclear reactor?

Answer 33

boron, they limit the rate of fission by absorbing excess neutrons.

Question 34

What is shielding made of and why is it used in nuclear reactor?

Answer 34

Thick concrete ( can contain lead and other materials), to absorb the ionising radiation such as beta or gamma

Question 35

How does a nuclear reactor generate electricity?

Answer 35

A substance ( eg CO2) pumped around the reactor transfers the energy (by heating) to the water in the heat exchanger. The water turns to steam, which turns a turbine, which turns a generator and generates electricity.

Question 36

What is nuclear fusion?

Answer 36

Two light nuclei collide at high speed, and fuse to create a heavier, larger nucleus.

Question 37

When does nuclear fusion happen?

Answer 37

At extremely high pressure and temperature

Question 38

Why can fusion only happen at high pressure and temp?

Answer 38

Because the positively charged nuclei have to get very close to fuse, so they need to be moving very fast to overcome the strong forces of electrostatic repulsion.

Question 39

Why does the nucleus formed after fusion not have a lot of mass?

Answer 39

Because some of the mass of the lighter nuclei is converted to energy, and then released, so the large nucleus isnt as heavy as the two light nuclei combined.