nuclear physics ☢️

Question 1

What are isotopes

Answer 1

atoms of the same element that have the same proton number but different nucleon number.

Question 2

What are nucleons

Answer 2

Protons and Neutrons.

Question 3

What force binds the protons and neutrons together

Answer 3

“Strong Nuclear force”

Question 4

When does a nucleus disintegrate

Answer 4

When it is unstable

Question 5

When is a nucleus considered unstable

Answer 5

When the atom has extra neutrons or protons it creates extra energy in the nucleus and causes the atom to become unbalanced or unstable.

Question 6

What does it mean for nucleus to disintegrate

Answer 6

The nucleus breaks up and radiates a tiny particle in order to achieve stability

Question 7

What does it mean for a material to be radioactive

Answer 7

The material emits nuclear radiation

Question 8

What is the meaning of “radioactive decay”

Answer 8

Disintegrations of a heavy nucleus which is random and spontaneous. They can result in the emission of α-particles or β-particles and/or γ-radiation.

Question 9

What does it mean to have an ionizing effect

Answer 9

Ability to remove electrons from atoms in its path. This makes all the atoms in its path ions

Question 10

What are the 3 types of radiation

Answer 10

Alpha
Beta
Gamma

Question 11

What is each radiation stopped by

Answer 11

Alpha - 1 sheet of paper
beta - A sheet of aluminium
gamma - 2 cm or more of lead/thick lead/50 cm of concrete (reduces intensity not fully stop)

Question 12

Speed of 3 radiations

Answer 12

Alpha - slowest of 3 = 0.1 * c
beta - faster than alpha, slower than gamma = 0.9 * c
gamma - fastest = c

Question 13

Mass of 3 radiations

Answer 13

Alpha - heaviest
beta - lighter than alpha, heavier than gamma
gamma - none

Question 14

Relative charges and ionizing powers of 3 radiations

Answer 14

Alpha = +2, strong ionizing
Beta = -1, weak ionizing
gamma = 0, very weak ionizing

Question 15

Effects of electromagnetic fields on 3 radiation

Answer 15

Alpha and beta - deflected by magnetic and electric fields
Gamma - Not deflected by any fields

Question 16

What are alpha particles made off

Answer 16

2 protons, 2 neutrons.

Similar structure to nucleus of helium

Question 17

What are beta particles made off

Answer 17

Each particle is an electron

Question 18

What are gamma particles made off

Answer 18

Electromagnetic waves similar to X rays

Question 19

Why are alpha and beta particles deflected in fields

in a magnetic field -
in an electric field -
which gets deflected more in both and which diretion

Answer 19

Alpha beam - flow of positively charged particles (same flow as current)
Beta particles - electrons (flow opp to current)

In a magnetic field - both follow flemings left hand rule

In an electric field - if they pass 2 oppositely charged plates, they experience a force

Beta particles deflected more in both since its lighter but in the opposite direction to alpha particles since charges are opposite

Question 20

how can the deflection of alpha and beta rays in magnetic fields be found?

Answer 20

alpha particles are heavy and a flow of positively charged particles, so it is equivalent to an electric current, hence we can use Flemings’ left-hand rule to find the direction of deflection. As it is heavy it is deflected less

(since its positive, its the same direction as conventional current hence alpha is left hand rule and beta is the opp of wtv alpa is)

beta particles are much lighter and are a flow of negatively charged particles so it is equivalent to an electron flowing in a magnetic field, which is the opposite direction of the current flow. As it is light it deflects more

Question 21

background radiation definition

Answer 21

Background radiation is the radiation that is present all around in the environment

Question 22

what are the factors that make a significant contribution to background radiation

Answer 22

radon gas (in the air)
rocks and buildings
food and drink
cosmic rays

Question 23

how is a Geiger muller tube used to detect alpha particles

Answer 23

if an alpha particle enters the tube, sparks are produced towards the negative plate and a big and loud sound is created

Question 24

how is a Geiger muller tube used to detect beta particles

Answer 24

if a beta particle enters the tube, sparks are produced towards the positive plate, this spark is fast and a low sound is produced

Question 25

how is a Geiger muller tube used to detect gamma particles

Answer 25

if a gamma particle enters the tube, trail of sparks, no sound and no deflection occurs

Question 26

what are the 3 possible apparatuses a GM tube can be connected to

what does each do

Answer 26

ratemeter - How many of that radiations particles are detected per second. Eg: 100 alpha particles detected per second so the reading is 100 counts per second.
scaler - total number of particles detected by the GM tube
amplifier and loudspeaker - makes a ‘click’ sound when a particle or burst of gamma radiation is detected

Question 27

what is a corrected count rate

Answer 27

the count rate subtracted by the background radiation count

Question 28

properties of alpha decay

Answer 28

decreases the mass number by 4
atomic number decreases by 2
doesn’t form isotopes but rather a new element altogether
produces a helium atom
eg: parent nuclei —> parent nuclei (mass no -4, proton no -2) + helium (mass no 4, proton no 2)

Question 29

properties of beta decay

Answer 29

beta particles breakdown a neutron into 3 parts
proton
electron
antineutrino (fast moving massless, chargeless particle)
no change in the mass number since one neutron gets converted to one proton
beta proton number decreases by 1
the atoms proton number increases by 1

Question 30

what kind of particle is an alpha, gama and beta

Answer 30

gamma is electromagnetic
beta is electron
alpha is a helium nucleus

Question 31

How does risk of exposure to radiation vary

Answer 31

Greater the intensity of the radiation and longer the exposure the greater the risk

Question 32

Effects of ionising nuclear radiations on living things

Answer 32

Mutations - Changes in genetic instructions which may grow abnormally and cause cancer

cell death

Question 33

Which radiation is most harmful and why

Answer 33

Alpha radiation - highest ionizing power

Question 34

Which radiations are potentially harmful to internal organs and which arent.

Answer 34

Harmful - beta and gamma because they can penetrate through to the internal organs.

Not harmful - Alpha particles. They can’t penetrate the skin and hence can’t reach the internal organs.

Question 35

Why is radioactive gas and dust especially harmful

Answer 35

They are taken in the body with air, food and drinks

Question 36

Give an equation in terms of parent nucleus, daughter nucleus and decay products.

Answer 36

Parent nucleus —> daughter nucleus + decay products

Question 37

What happens when an unstable nucleus undergoes Alpha decay

Answer 37

Original isotope loses 2 protons and 2 neutrons

Question 38

What happens when a particle undergoes beta decay

Answer 38

A neutron becomes a proton
An electron and an anti-neutrino is given out

Question 39

What happens in gamma emission

Answer 39

When beta or alpha decay take place, protons and neutrons rearrange themselves to become more stable. They lose energy when they do this. That lost energy is emitted as a burst of gamma radiation

Question 40

What is a half-life of a particular isotope

Answer 40

time taken for half the nuclei of that isotope in any sample to decay

Question 41

What is activity
What is the unit

Answer 41

Average number of disintegrations per second is known as the activity

Unit: Becquerel (Bq)

Question 42

What is the stability line

What is above the stability line? What happens

What is below the stability line? What happens

what happens to the heaviest isotopes

Answer 42

Stable isotopes lie on the stability line

Isotopes above the stability line have too many neutrons to be stable. They undergo beta- (electron) decay to reduce the number of neutrons.

Isotopes below the stability line have too few neutrons to be stable. They undergo beta+ (positron) decay to increase the number of neutrons.

Heaviest isotopes decay by alpha emission.

Question 43

In a cathode-ray tube, a hot tungsten cathode releases particles by thermionic emission.
What are these particles?

Answer 43

electrons

Question 44

a radioactive nucleus emits a beta particle
what happens to the proton number of the nucleus of the atom

Answer 44

proton number increases by 1

Question 45

what is always a product of nuclear fission

Answer 45

neutron

Question 46

How many isotopes can an atom have

Answer 46

more than one

Question 47

In which decay does the nucleus change to a diff element

Answer 47

α-decay or β-decay

Question 48

2 economic issues involved in the storage of radioactive materials with very long half-lives

Answer 48

high cost of storage/shielding/guarding/ need to store for a long time

OR reduction in tourism

OR loss of farming produce/land

OR reduction of land/property values

Question 49

2 social issues involved in the storage of radioactive materials with very long half-lives

Answer 49

fear of cancer/ causes cancer/genetic mutations/radiation sickness in people/ animals

OR local objections

OR cause people to move away

Question 50

2 environmental issues involved in the storage of radioactive materials with very long half-lives

Answer 50

crop mutations

OR leakage into water supplies

OR pollution of atmosphere/water supply

Question 51

Why are alpha particles more stongly ionising than beta particles

Answer 51

larger charge (+2 vs -1)

slower moving

more massive/greater volume/ more chance of collision