Radioactivity

Question 1

What size are small molecules

Answer 1

10(-10)m

Question 2

Why are atoms neutral

Answer 2

Because they have the same number or protons and electrons and they have an equal but opposite charge

Question 3

What do electrons do in an atom

Answer 3

The orbits the nucleus at different set distances from the nucleus

Question 4

When do electrons change orbit

Answer 4

When there’s absorption or emission of electromagnetic radiation

Question 5

How do atoms form positive ions

Answer 5

If an outer electron absorbs radiation with enough energy it can move so far that it leaves the atom and is now a free electron and the atom is said to have ionised and is now a positive ion - there are now more protons than electrons

Question 6

What are alpha, beta minus, positron, gamma rays and neutron radiation emitted from and how

Answer 6

From an unstable nuclei in a random process

Question 7

What are alpha, beta minus, positron and gamma rays all

Answer 7

Ionising radiations

Question 8

What is background radiation

Answer 8

The low level radiation that is around us all the time

Question 9

What is alpha radiation

Answer 9

When an alpha particle is emitted from the nucleus

Question 10

What is a beta minus particle

Answer 10

A fast-moving electron released by the nucleus

Question 11

What is a beta plus particle

Answer 11

A fast moving positron (the antiparticle of the electron)

Question 12

Mass of a beta minus particle

Answer 12

No mass

Question 13

Charge beta minus particle

Answer 13

-1

Question 14

Mass of beta plus particle

Answer 14

0.0005(same as electron)

Question 15

Charge of beta plus particle

Answer 15

+1

Question 16

What is an alpha particle equivalent too

Answer 16

A helium nucleus

Question 17

What is a beta particle

Answer 17

An electron emitted from the nucleus

Question 18

What is a gamma ray

Answer 18

An electromagnetic radiation

Question 19

Where does background radiation come from

Answer 19

Radioactivity of naturally occurring unstable isotopes (in air, some foods, building mats), radiation from space aka cosmic rays - mostly from sun, radiation due to human activity e.g. fallout from nuclear explosions or nuclear waste

Question 20

How can radioactivity be measured

Answer 20

Using a Geiger-müller tube - which clicks each time it detects radiation
Or photographic film - more radiation the films exposed to, the darker it becomes

Question 21

How ionising are alpha particles and why

Answer 21

Stonefly ionising because of their size

Question 22

How ionising are beta particles

Answer 22

Moderately ionising

Question 23

How ionising are gamma rays and why

Answer 23

Weakly ionising because they tend to pass through rather than collide with atoms

Question 24

Process of beta minus decay

Answer 24

An atom converts one of its neutrons into a protons while releasing an electron

Question 25

Process of beta plus decay

Answer 25

a proton in the parent nucleus decays into a neutron that remains in the daughter nucleus, and the nucleus emits a neutrino and a positron,

Question 26

What happens to the mass and atomic number to alpha decay

Answer 26

Mass number decreases by 4 | Atomic number decreases by 2

Question 27

What happens to the mass and atomic number to beta minus decay

Answer 27

Mass number doesn’t change | Atomic number increase by 1

Question 28

What happens to the mass and atomic number to beta plus decay

Answer 28

Mass number doesn’t change | Atomic number decreases by 1

Question 29

What happens to the mass and atomic number to neutron emission

Answer 29

Mass number decreases by 1 | Atomic number stays the same

Question 30

What happens to the mass and atomic number of gamma rays

Answer 30

Neither change

Question 31

What form are nuclear equations written in

Answer 31

Atoms before decay — atom after decay + radiation emitted (alpha, beta minus, beta plus, neutron emission)

Question 32

What often happens to nuclei that have undergone radioactive decay

Answer 32

The often undergo nuclear rearrangement with a loss of energy as gamma radiation

Question 33

What is activity

Answer 33

The rate at which a source decays

Question 34

How does the activity of a radioactive source decrease over a period of time

Answer 34

Each time a radioactive nucleus decays, one more radioactive nucleus disappears, as the unstable nuclei all steadily disappear, the activity as a whole will decrease

Question 35

What is half-life

Answer 35

The average time taken for the number of radioactive nuclei in an isotope to halve

Question 36

What is the unit of activity of a radioactive isotope

Answer 36

Becquerel, Bq

Question 37

What is a random process and how can we calculate it

Answer 37

Radioactive sources contain radioactive isotopes that give out radiation from the nuclei of their atoms -process=random If there are lots of nuclei u can predict how many will have decayed in a given time using half-life

Question 38

What are the dangers of ionising radiation

Answer 38

It can enter living cells and ionise atoms and molecules within them-lead to tissue damage Lower doses tend to cause minor damage without killing the cells, can give rise to mutant cells dividing uncontrollably-cancer Higher doses can kill cells completely -lead to radiation sickness

Question 39

Dangers of beta and gamma radiation

Answer 39

Can penetrate the body and get into vital organs | Alpha cannot penetrate skin

Question 40

How can we prevent harm caused by ionising radiation

Answer 40

Hospitals limit staff and patient exposure to radiation e.g. shielding is used protecting staff and untreated body parts white short half-life used

Question 41

What are the differences between irradiation effects and contamination effects

Answer 41

Contamination- contaminating atoms can decay and release radiation, radioactive particles could get in your body and the person becomes contaminated