Unit 5 - Nuclear Physics

Question 0

What does the nucleons number tell us? (Mass number)

Answer 0

This tells us the number of protons and neutrons in the atom/nucleus

Question 1

What does the proton number tell us?

Answer 1

Number of protons in the atom/nucleus

Question 2

What is the symbol for proton number?

Answer 2

Z

Question 3

What is the symbol for nucleon number? (Mass)

Answer 3

A

Question 4

What is the equation to calculate the number of neutrons?

Answer 4

N = A - Z

Question 5

What are isotopes?

Answer 5

These are atoms of the same element which have the same number of protons but a different number of neutrons

Question 6

Why are some atoms unstable?

Answer 6

If an atom has an imbalance of protons and neutrons in the nucleus it will be unstable

Question 7

How does the nucleus try to become stable?

Answer 7

Breaking up into stable fragments : RADIOACTIVE DECAY

Question 8

What is ALPHA?

Answer 8

A helium nucleus (2 protons 2 neutrons)

Question 9

What can alpha be stopped with?

Answer 9

Thin sheet of paper, skin or few cm of air

Question 10

What is ALPHAS ionising power?

Answer 10

Very HIGH ionising - most damaging inside the body

LOW penetrating

Question 11

What is BETA?

Answer 11

Fast moving electron

Question 12

What can stop Beta?

Answer 12

Few mm of aluminium or up to a metre of air

Question 13

What is BETA’ ionising power?

Answer 13

Medium ionising

Medium penetration

Question 14

What is GAMMA?

Answer 14

High energy electromagnetic wave

Question 15

What can stop GAMMA?

Answer 15

Several cm of lead or very thick concrete

Question 16

What is GAMMA’ ionising power?

Answer 16

LOW ionising

HIGH penetrating

Question 17

What is the ALPHA symbol?

Answer 17

4
HE
2

Question 18

What is the BETA symbol?

Answer 18

0
E
-1

Question 19

What’s the equation for Alpha decay?

Answer 19

A A -4 4
❌ ➡️➡️➡️➡️ ❌ ➕ He
Z Z -2 2

Question 20

What’s the equation for BETA decay?

Answer 20

A A 0
❌ ➡️➡️➡️➡️ ❌ ➕ He
Z Z +1 -1

Question 21

Is radioactive decay predictable?

Answer 21

No it is RANDOM

Question 22

How can you get more accurate information/results if decay is random?

Answer 22

REPEAT

MEASURE OVER A LONG TIME

Question 23

What is the half life?

Answer 23

The half life is the time it takes for HALF the UNSTABLE atoms to DECAY

Question 24

What is the name called for measuring the number of radioactive decays per second?

Answer 24

The activity

Question 25

What is the activity measured in?

Answer 25

Becquerel, Bq

Question 26

The activity of a sample of radioactive material will depend on what two things?

Answer 26

1. The number of unstable/radioactive atoms present | 2. The half life of the atoms

Question 27

More atoms present... The shorter the half life...

Answer 27

... greater the activity ... greater the activity

Question 28

Example question: a radioactive isotope has an activity of 6400Bq. The half life of the isotope is 8 hours. What's the activity after 32 hours?

Answer 28

1 2 6400Bq ➡️➡️➡️➡️ 3200Bq➡️➡️➡️➡️ 1600Bq 8 hours 8 hours 3 4 ➡️➡️➡️➡️ 800 Bq ➡️➡️➡️➡️ 400 Bq 8 hours 8 hours 4 half lives so 8✖️4 = 32 hours

Question 29

List two uses of radioactive materials..

Answer 29

Sterilising medical equipment Killing cancer cells

Question 30

Explain in detail a use for a radioactive material

Answer 30

Medical tracer in monitoring internal organs -camera in body Isotope: Technetium -99 (GAMMA) Reason: Gamma passes out of body easily The half life is short so will not remain in body for a long time

Question 31

What is nuclear fission?

Answer 31

Splitting of a nucleus and releasing heat energy

Question 32

What is induced fission?

Answer 32

Bombarding elements with neutrons so they can undergo fission

Question 33

What happens during fission of Uranium-235?

Answer 33

Neutrons are emitted as fission products | Large amount of energy is released

Question 34

What is a moderator?

Answer 34

Slows down neutrons Allow them to cause further fission Surrounds the fuel rods

Question 35

What two things can be used as moderators?

Answer 35

Water or graphite rods

Question 36

What's the advantage of using water?

Answer 36

Also used as a coolant to transfer heat energy away from the reactor to make electricity If lost the reactor will over heat as neutrons won't be slowed down

Question 37

What are control rods used for?

Answer 37

Stops/controls the number of thermal neutrons inside fuel rods Absorb neutrons preventing further fusion

Question 38

If a fault occurs to do with the control rods what happens?

Answer 38

they will drop into reactor stopping chain reaction

Question 39

What is used as a vessel for the reactor?

Answer 39

Steel and surrounded by concrete

Question 40

Here should the fuel pods be put after the uranium has been used up?

Answer 40

In cooling ponds Cools down heat and water is shielding from radiation After years, are reprocessed

Question 41

What is nuclear fusion?

Answer 41

When two smaller nuclei are joined together to make a larger one

Question 42

Why is the neutrons generating lots of energy stored in concrete? (Nuclear fusion)

Answer 42

Prevent any radiation escaping - protect workers

Question 43

Advantage of nuclear FUSION

Answer 43

Does not produce green house gases | No long lived radioactive material produced

Question 44

Disadvantage of nuclear FUSION

Answer 44

High temperature required Shielding neutrons in concrete High energy input required

Question 45

Advantage of nuclear FISSION

Answer 45

Does not produce greenhouse gases Uses small amount of fuel Large amount of power produced

Question 46

Disadvantages to nuclear FISSION

Answer 46

Radioactive material produced has long half life | Expense - decommissioning power station + storing waste