Radiation

Question 1

Describe the arrangement of subatomic particles in a atom

Answer 1

A positively charged nucleus consisting of protons and neutrons surrounded by negatively charged electrons.

Question 2

What is an ion?

Answer 2

An atom that has gained or lost electrons to become charged

Question 3

Who proposed the plum pudding model?

Answer 3

J.J Thompson

Question 4

Describe the plum pudding model

Answer 4

A positively charged sphere with negatively charged electrons embedded in it

Question 5

Describe what happened in Rutherford’s alpha particle scattering experiment

Answer 5

• Alpha particles were fired at gold foil suspended in a vacuum
• Most alpha particles passed straight through the foil
• A small amount were deflected as they passed through the foil
• A very small amount came straight back off the foil

Question 6

What did Rutherford discover from his alpha particle scattering experiment?

Answer 6

• Most of the atom is empty space
• There is a concentration of positive charge in the atom
• The positive charge and mass was concentrated in a tiny volume in the atom (the nucleus)

Question 7

What did J.J Thompson discover?

Answer 7

Electrons

Question 8

What did Niels Bohr change about Rutherford’s version of the nuclear model?

Answer 8

Electrons were only allowed to occupy particular orbits

Question 9

What is an atom?

Answer 9

A positively charged nucleus of protons and neutrons surrounded by negatively charged electrons

Question 10

Compare the size of the nucleus to the size of the whole atom

Answer 10

Nuclear radius is much smaller than the atom as a whole

Question 11

Where is most of the mass stored in an atom?

Answer 11

The nucleus

Question 12

What is an isotope?

Answer 12

An atom with the same atomic number but a different atomic mass to that of a typical atom of that element

Question 13

Why does an isotope have a different atomic mass?

Answer 13

It has a different number of neutrons

Question 14

Was charge does a nucleus have?

Answer 14

Positive

Question 15

What is the charge of a proton?

Answer 15

+1

Question 16

What is the charge of a neutron?

Answer 16

0

Question 17

What is the charge of an electron?

Answer 17

-1

Question 18

What is the relative atomic mass of a
proton?

Answer 18

1

Question 19

What is the relative atomic mass of a neutron?

Answer 19

1

Question 20

What is the relative atomic mass of an electron?

Answer 20

1
——-
1835

Question 21

What is the relative atomic mass of a positron?

Answer 21

1
——-
1835

Question 22

What is the charge of a positron?

Answer 22

+1

Question 23

Electrons _____ around the nucleus

Answer 23

Orbit

Question 24

What happens to electrons if EM radiation is absorbed or emitted?

Answer 24

It will change orbit

Question 25

How are positive ions formed?

Answer 25

By an atom losing electrons

Question 26

What are the different ionising radiation types?

Answer 26

- Alpha - Beta minus (ß-) - Positron (ß+) - Gamma

Question 27

Describe the structure of an alpha particle

Answer 27

The same as a helium nucleus: two protons, two neutrons

Question 28

Which type of radiation is the most ionising?

Answer 28

Alpha

Question 29

What type of radiation is stopped by paper?

Answer 29

Alpha radiation

Question 30

What happens in beta minus decay (ß-)?

Answer 30

A **neutron** will turn into **proton** and emit an **electron**

Question 31

What type of radiation is stopped by thin aluminium?

Answer 31

Beta minus (ß-)

Question 32

What is radioactive activity measured in?

Answer 32

Becquerels (Bq)

Question 33

What happens during positron decay?

Answer 33

A **proton** turns into a **neutron** and a **positron** is emitted from the nucleus

Question 34

What is a positron?

Answer 34

A positively charged electron

Question 35

What happens once a positron is emitted?

Answer 35

It is immediately annihilated

Question 36

What is the most penetrating form of ionising radiation?

Answer 36

Gamma radiation

Question 37

What is the most dangerous type of radiation if inside a human?

Answer 37

Alpha

Question 38

What type of radiation is only stopped by thick lead?

Answer 38

Gamma radiation

Question 39

What happens to the nucleus of an atom when it emits a gamma ray?

Answer 39

Nothing

Question 40

Where is ionising radiation emitted from?

Answer 40

Unstable nuclei

Question 41

What is neutron emission?

Answer 41

When a neutron is emitted from the nucleus of an atom

Question 42

What is background radiation?

Answer 42

The amount of ionising radiation from natural and artificial sources

Question 43

Name 4 sources of background radiation

Answer 43

- Radon gas - Food & drink - Medical uses - Cosmic radiation

Question 44

What piece of equipment can be used to measure the level of radiation?

Answer 44

Geiger-Müller tube (Geiger Counter)

Question 45

What happens to the radioactivity of a source over time?

Answer 45

It decreases

Question 46

What is half life?

Answer 46

The time taken for the activity from a radioisotope to decrease by half **OR** The time taken for the number of radioactive nuclei in a sample to decrease by half

Question 47

What is nuclear fission?

Answer 47

The splitting of a large atomic nucleus into smaller nuclei

Question 48

Describe what happens in a nuclear reactor

Answer 48

- A neutron is absorbed into a Uranium-235 nucleus causing it to become unstable - It splits into 2 daughter nuclei and releases 2-3 neutrons - This causes a chain reaction

Question 49

What are the advantages of using nuclear power to generate electricity?

Answer 49

- No CO₂ emissions - Low fuel costs - Power station has long lifetime

Question 50

What are the disadvantages of using nuclear power to generate electricity?

Answer 50

- Negative public perception - Radioactive waste disposal is difficult and expensive - High cost to build and decommission - Large scale accidents can be catastrophic

Question 51

How is nuclear fission used to generate power?

Answer 51

Energy from neutrons is passed on to other components to heat water to turn turbines to generate electricity

Question 52

How are nuclear chain reactions controlled?

Answer 52

With a **moderator** and **control rods**

Question 53

What is nuclear fusion?

Answer 53

When two smaller nuclei join together to make one heavier nucleus, accompanied by a release of energy

Question 54

What is the energy source for stars?

Answer 54

Nuclear fusion

Question 55

Why can’t nuclear fusion happen at low temperatures or pressures?

Answer 55

Due to the electrostatic repulsion of the protons in the nuclei

Question 56

Why isn’t nuclear fusion a viable source of energy on Earth currently?

Answer 56

Due to the high temperatures and pressures required, more energy is used to create the reaction than can be usefully harnessed

Question 57

Name some uses of radioactivity

Answer 57

- In smoke alarms - For irradiating food - For sterilisation of equipment - Cancer diagnosis and treatment

Question 58

How does the irridation of food work using radiation?

Answer 58

- Food is exposed to a radoactive souce eg. Cobalt-60 - This will emmit gamma rays - The gamma rays kill all bacteria present - This will preserve the food for longer

Question 59

What causes atoms to decay?

Answer 59

Them becoming unstable

Question 60

When an atom becomes unstable, what happens?

Answer 60

It decays

Question 61

How do smoke alarms work?

Answer 61

- Alpha particles are present that ionise the air - These ions carry an electric charge - Smoke will slow down the ions, reducing the current, setting off the alarm

Question 62

How is radiation used to measure thickness?

Answer 62

- Radiation fired through material - The amount of radioactive particles that go through determines the thickness

Question 63

Which type of radiation is an antimatter particle?

Answer 63

Positron

Question 64

What does a moderator do?

Answer 64

Slow down neutrons

Question 65

What do control rods do?

Answer 65

Lower to absorb neutrons to slow down the reaction