Atomic Structure (2018+ Exam Q's)

Question 1

What is meant by the ‘random nature of radioactive decay’?

Answer 1

What is meant by the ‘random nature of radioactive decay’?

Question 2

Radioactive waste from nuclear power stations is a man-made source of background radiation.

(Give one other man-made source of background radiation

Answer 2

*   (medical) x-rays
*   radiotherapy
*   nuclear weapons (testing)
allow nuclear fallout
*   named nuclear disaster e.g. Chernobyl / Fukushima / Three Mile Island.

Question 3

Describe the process of nuclear fission inside a nuclear reactor.

Answer 3

neutron absorbed by a uranium nucleus
nucleus splits into two parts
and (2/3) neutrons (are released)
and gamma rays (are emitted)

Question 4

Explain how the process of nuclear fusion leads to the release of energy

Answer 4

ighter nuclei join to form heavier nuclei
allow specific examples

some of the mass (of the nuclei) is converted to energy (of radiation)

Question 5

Explain the advantage of the radioactive waste having a shorter half-life

Answer 5

activity decreases quickly
allow nuclei / waste will decay at a greater rate
ignore waste is radioactive for less time
risk of harm decreases quickly

Question 6

Explain why contamination of the inside of the human body by a radioactive material that
emits alpha radiation is highly dangerous

Answer 6

alpha radiation is highly ionising
causing an increased risk of cancer
until the radioactive material is removed / excreted

Question 7

Why does the alarm switch on when smoke particles enter the plastic casing?

Answer 7

smoke absorbs / stops alpha radiation

Question 8

Why is it safe to use a source of alpha radiation in a house?

Answer 8

alpha radiation is not very penetrating

Question 9

The smoke alarm would not work with a radiation source that emits beta or gamma
radiation.

Answer 9

beta and gamma radiation will penetrate smoke
no change (in the count rate) would be detected

Question 10

Explain why the radiation source inside the smoke alarm should have a long half-life.

Answer 10

(a long half-life means) the count rate is (approximately) constant
use graph

Question 11

Explain the ideal properties of a radioactive source for use in medical diagnosis

Answer 11

short half-life or half-life of a few hours
(short half-life means) less damage to cells / tissues / organs / body
low ionising power
(low ionising power means) less damage to cells / tissues / organs / body
highly penetrating
(highly penetrating means) it can be detected outside the body
emits gamma radiation

Question 12

Describe the advantages of nuclear power compared with the use of shale gas to generate
electricity

Answer 12

no carbon dioxide emitted (to produce electricity)
no greenhouse gases is insufficient
doesn’t cause global warming
allow climate change or greenhouse effect for global warming
nuclear power doesn’t cause earthquakes
more energy released per kg of fuel (

Question 13

What is the name of one fuel used in nuclear power stations?

Answer 13

uranium
or
plutonium

Question 14

Describe the process of nuclear fission

Answer 14

a neutron is absorbed by a (large) nucleus
a description in terms of only atoms negates first two marking points

the nucleus splits into two (smaller) nuclei

releasing energy (and gamma rays)

and (two / three) neutrons

Question 15

Explain what happens in the process of nuclear fusion.

Answer 15

light nuclei

join to form a heavier nucleus

(some of the) mass of the nuclei is converted to energy

Question 16

Suggest two advantages of the fuel used in a fusion reactor compared with the fuel used in
a fission reactor

Answer 16

• easy to obtain / extract
• available in (very) large amounts
• releases more energy (per kg)

Question 17

Explain how the paths of the alpha particles were used to develop the nuclear model of the
atom.

Answer 17

most alpha particles pass straight through the atom

which shows that the atom is mostly empty space

very few alpha particles are deflected through a large angle

which shows the atom contains a nucleus where the mass / charge
of the atom is concentrated

Question 18

Explain how the distance at which an electron orbits the nucleus may be changed.

Answer 18

electron may absorb electromagnetic radiation

electromagnetic radiation

(and) move further from the nucleus

to a higher energy leve

Question 19

Explain how the energy released by the chain reaction is affected by moving the control
rods.

Answer 19

lowering the control rods increases the number of neutrons absorbed
accept converse description

(so) energy released decreases

Question 20

Nuclear fusion is the joining together of ______

Answer 20

nuclei

Question 21

During nuclear fusion the total mass of the particles

Answer 21

decreases

Question 22

The models were tested before starting to build the first commercial nuclear fusion power
station.
Suggest two reasons why models were tested

Answer 22

to make sure the fusion process is possible
to develop an understanding of the process
to make adaptations to the process
to assess the efficiency of the process
to make predictions
assess safety risks
to assess environmental impact
set-up cost is lower (for small scale experiments)

Question 23

Explain one environmental effect of generating electricity using fossil fuels.

Question 24

Suggest one reason why the Banana Equivalent Dose may help the public be more aware
of radiation risks.

Answer 24

people are able to compare a radiation risk / dose / hazard to the radiation dose from
(eating) bananas

Question 25

shorter half life means_ __ to a patient

Answer 25

exposure time to radiation is shorter

Question 26

A teacher demonstrates the penetration of alpha, beta and gamma radiation through
different materials.
Give two safety precautions the teacher should have taken in the demonstration

Answer 26

• (radioactive) source not pointed at students
• (radioactive) source outside the box for minimum time necessary
• safety glasses or eye protection or do not look at source
• gloves
• (radioactive) source held away from body
• (radioactive) source held with tongs / forceps

Question 27

The half-life of the radioactive source used was very short.
Give one reason why this radioactive source would be much less hazardous after 800
seconds

Answer 27

very small amount of radiation emitte

Question 28

Explain what led to the plum pudding model of the atom being replaced by the nuclear model of
the atom

Answer 28

• alpha particle scattering experiment
• alpha particles directed at gold foil
• most alpha particles pass straight through
• (so) most of atom is empty space
• a few alpha particles deflected through large angles
• (so) mass is concentrated at centre of atom
• (and) nucleus is (positively) charged
• plum pudding model has mass spread throughout atom
• plum pudding model has charge spread throughout atom