P6 Radioactivity

Question 1

What does it mean for an electron to become excited?

Answer 1

Move to a higher energy level

Question 2

When can electrons in a gas become excited?

Answer 2

When the gas is heated / current is passed through it

Question 3

After becoming excited electrons fall back down to their shell and lose energy. This is emitted as?

Answer 3

An electromagnetic wave in a random direction

Question 4

The bigger the fall, the more…

Answer 4

Energy lost
Energetic EM wave emitted

Question 5

Every element has different ____ levels. Therefore if there is an unknown gas we can ____ it and see which ___ it emits

Answer 5

Energy
Heat
Wavelengths

Question 6

All EM waves except what can be emitted in this way?

Answer 6

Gamma

Question 7

When light of all colours is shone through a cold gas, most wavelengths…

Answer 7

Go straight through

Question 8

Electrons can only absorb light with…

Answer 8

Just the right energy to move them up to another energy shell

Question 9

After electrons absorb light they’ll then fall back down, emitting…

Answer 9

An identical wavelength (colour) of light in a random direction

Question 10

An electron can gain enough energy to ___ ___ from the atom. This is known as ____ and we say the atom has been ____

Answer 10

Break free
Ionisation
Ionised

Question 11

Some isotopes contain too many ____, this makes them ___ and therefore radioactive. We call them _____

Answer 11

Neutrons
Unstable
Radioisotopes

Question 12

Radioactive substances consist of unstable ___ which ___, emitting alpha / beta / gamma

Answer 12

Nuclei
Decay

Question 13

What is an alpha particle?

Answer 13

Two protons and two neutrons
The same as a helium nucleus

Question 14

A beta particle is?

Answer 14

A high energy electron

Question 15

What is gamma?

Answer 15

An electromagnetic wave, high frequency, short wavelength

Question 16

Absorbing what can make a material radioactive?

Answer 16

Neutrons

Question 17

Losing a gamma ray has what effect on a nucleus?

Answer 17

The nucleus stays the same but has less energy

Question 18

How is a beta particle formed?

Answer 18

A neutron turns into a proton + electron

Question 19

Alpha is how ionising?

Answer 19

Highly

Question 20

Beta is how ionising?

Answer 20

Moderately

Question 21

Gamma is how ionising?

Answer 21

Weakly

Question 22

Alpha is how penetrating?

Answer 22

Weakly

Question 23

Beta is how penetrating?

Answer 23

Moderately

Question 24

Gamma is how penetrating?

Answer 24

Highly

Question 25

Alpha can be stopped by…

Answer 25

Paper 5cm of air

Question 26

Beta can be stopped by…

Answer 26

3-5mm of aluminium

Question 27

Gamma can be stopped by…

Answer 27

Thick lead Metres of concrete

Question 28

Why is ionisation of living things potentially dangerous?

Answer 28

Ionisation within living cells can damage DNA —> cell mutation / death

Question 29

What is irradiation?

Answer 29

When the radiation from a material damages the cells. You can move away from the source and end the irradiation

Question 30

What is contamination?

Answer 30

If some of the radioactive material itself is swallowed or inhaled, it emits radiation inside the body, causing damage

Question 31

List the precautions your teacher took while handling radioactive sources

Answer 31

Wearing lab coat and gloves to avoid contamination Tongs and source holder to increase distance between source + people Experiment done quickly to limit time close to source Pointed sources away from students

Question 32

What is background radiation?

Answer 32

Radiation all around us

Question 33

What is half-life?

Answer 33

The half-life of a radioactive element is the time it takes for half the nuclei in a sample to decay

Question 34

Carbon-__ is made in the upper atmosphere by ___ __ and decays elsewhere at the same rate

Answer 34

14 Neutron capture

Question 35

Living organisms take in ___ including some of the radioactive C-14

Answer 35

Carbon

Question 36

When organisms die they stop taking in C02 (plants) or ____ (animals) so the amount of C-14 in them starts _____ as it radioactively decays

Answer 36

Glucose Decreasing

Question 37

C-14 has a half life of….

Answer 37

5730 years

Question 38

The ratio of C-14 to C-__ in living objects can be compared to the artefact and therefore it can be ___

Answer 38

12 Dated

Question 39

How is radioactivity used to treat cancer?

Answer 39

An x-ray or gamma source is rotated around patient’s body, aiming x-rays / gamma rays at tumour. This ensures the tumour gets large amount of radiation (hopefully cells die) while healthy cells receive lowest amount possible

Question 40

What radiations are emitted from medical tracers we use? Why?

Answer 40

Usually gamma - most penetrating, least ionising Sometimes beta

Question 41

Why is alpha never used for medical tracers?

Answer 41

Would cause damage (most ionising) and wouldn’t be detected (least penetrating)

Question 42

How do we get medical tracers into patient?

Answer 42

Injection, ingestion, inhalation (3 Is)

Question 43

Radioactive iodine behaves the same as non-radioactive iodine. This is good because?

Answer 43

Our body won’t reject it

Question 44

An appropriate half-life for a medical tracer might be…

Answer 44

4-6 hours

Question 45

What is nuclear fission?

Answer 45

The process of splitting a heavy nucleus to form 2 or more small nuclei, releasing large quantities of energy

Question 46

What is a chain reaction?

Answer 46

A reaction where the product of the first reaction causes further reactions to take place

Question 47

A ___ moving neutron is absorbed by the nucleus of a ____-235 atom

Answer 47

Slow Uranium

Question 48

The uranium nucleus splits into two smaller, still _____ nuclei, releasing ____ and ____

Answer 48

Radioactive Heat Gamma

Question 49

When the uranium nucleus splits, 2 or 3 ___ are also released; these could be ___ by other uranium nuclei causing further ____ reactions

Answer 49

Neutrons Absorbed Fission

Question 50

Advantages of nuclear power?

Answer 50

Produces no C02 Stores more energy per kg than any other fuel (4 million times more than coal) Reliable, produces 24/7

Question 51

Disadvantages of nuclear power?

Answer 51

Generate nuclear waste that emit alpha, beta and gamma, and stay radioactive for millions of years - has to be treated, sealed and buried Closing power station is expensive because some parts have become radioactive by absorbing neutrons Nuclear accidents are rare but have serious consequences

Question 52

What is nuclear fusion?

Answer 52

The process of joining together two lighter nuclei to form one large nucleus, releasing large quantities of energy

Question 53

What happens if we bring two protons (hydrogen nuclei) together?

Answer 53

They repel

Question 54

In order to fuse, protons must move very fast. What must the temp of the substance be?

Answer 54

Extremely hot

Question 55

How do we increase the likelihood of successful collisions?

Answer 55

Increase pressure and density

Question 56

What does E= delta m c2 mean

Answer 56

Energy = change in mass x speed of light squared

Question 57

Energy and mass are…

Answer 57

Interchangeable

Question 58

If we can recreate nuclear fusion in a controlled way, we could produce energy that:

Answer 58

Produces no C02 Produces no long half-life waste Is inherently safe - if something goes wrong the temp drops, and the reaction stops

Question 59

What is an absorption spectrum?

Answer 59

A continuous spectrum with dark lines where particular wavelengths / frequencies of EM waves have been absorbed

Question 60

Where does background radiation come from?

Answer 60

The air, rocks, the sun, space and artificial sources

Question 61

Define radioactive decay

Answer 61

A random process by which an unstable nucleus loses energy by emission of radiation or a particle

Question 62

What is an emission spectrum?

Answer 62

A set of wavelengths / frequencies of EM waves emitted by an atom when excited electrons move to lower energy levels