Radioactivity

Question 1

What are radioactive elements?

Answer 1

Have atoms that have unstable nuclei because of unstable combinations of protons & neutrons.

Question 2

What is the process of radioactive decay?

Answer 2

Unstable atoms disintegrate or decay to form smaller, more stable atoms
They emit radiation when this happens

Question 3

What are the properties of alpha rays? How are they stopped? What is its charge?

Answer 3

Large, heavy, slow particles, Helium atoms that’s lost 2 electrons
Few cms of air, Thin sheet of paper
Positive

Question 4

What is background radiation? Sources?

Answer 4

Radiation that’s all around us & always present, caused by reaction of unstable nuclei 
Radon 
Carbon-14 
Cosmic rays 
Nuclear reactors

Question 5

What are everyday uses of radiation?

Answer 5

Gamma rays: kill cancer cells , Sterilise surgical instruments, Preserve perishable fish food, Detects leaks from underground pipes

Question 6

What happens when radiation is emitted?

Answer 6

Original element disintegrates into new element & smaller more stable atom formed

Question 7

What are the properties of beta rays? How are they stopped? What is its charge?

Answer 7

Small, light & fast-moving electrons
Few metres of air, Few mms of aluminium
Negative

Question 8

What are the properties of gamma rays? How are they stopped? What is its charge?

Answer 8

Fast & powerful electromagnetic radiation
Few cms of lead
None

Question 9

What is carbon-14 radiation?

Answer 9

Type of carbon found inside all living organisms

Question 10

What is radon radiation?

Answer 10

Radioactive gas emitted from granite rocks

Question 11

What is potassium radiation?

Answer 11

Measurable traces contained in some foods

Question 12

What are nuclear reactors radiation?

Answer 12

Waste from nuclear power stations

Question 13

What are radioactive materials radiation?

Answer 13

Used in medicine in hospitals

Question 14

What are cosmic rays radiation?

Answer 14

Rays reaching earth from space

Question 15

What is the definition of a half-life?

Answer 15

Time taken for radiation to fall by half

Question 16

What is ionisation?

Answer 16

Process of electrically neutral atoms becoming ions by radiation

Question 17

What is the common name for Alpha, Beta & Gamma rays?

Answer 17

Ionising radiations, as they cause ionisation

Question 18

How do we minimise risk form ionising radiation?

Answer 18

Maximise distance from person & radioactive source - at arms length, with tongs facing away from user
Minimise exposure time - work quickly, but carefully, kept in locked lead-lined container at all other times
Shield observer from source

Question 19

How is radiation used in industry?

Answer 19

Leaks from pipeline carrying oil or gas can be traced by injecting radioactive element into to it. Saves digging it all up
Right element should:
Have a half-life of few hours or days - long enough to be detected, short enough that isn’t safety problem
Be a beta emitter - alpha particles absorbed by soil, gamma rays would pass through medical pipe

Question 20

How is radiation used in medicine?

Answer 20

Used to kill cancer cells, gamma rays used as they can penetrate deep inside body, and can target tumour
Radiation source rotated to have maximum effect on cancer cells, but not destroy healthy cells surrounding tumour
Measures put in place to reduce harm to patients, e.g. radiotherapy treatment in series of very small doses

Question 21

How is radiation used in sterilisation?

Answer 21

Gamma rays sterilise plastic syringes, which would be damaged by heating them