radioactive materials

Question 1

what are nuclear wastes categorised in according to their level of risk?

Answer 1

• low level waste:
  slightly radioactive waste that is sealed + placed in landfills
• intermediate level waste:
  a lot is produced, deciding how to store = prob, most are mixed with concrete + stored in big containers
• high level waste:
  very radioactive waste, stored carefully. only small produced + doesn’t remain radioactive for long

Question 2

what are the 3 types of ionising radiation?

Answer 2

alpha
- absorbed by a few cm of air or thin sheet of paper

beta
- passes through air and paper but absorbed by few cm of aluminium

gamma
- very penetrating + needs many cm of lead to absorb most of it

Question 3

what is irradiation?

Answer 3

exposed to radiation

Question 4

what is contaminated?

Answer 4

radioactive material on skin, clothes or entered body

Question 5

rr

Answer 5

r

Question 6

what are the uses of radiation?

Answer 6

• high energy gamma rays destroy cancer cells
• sterilise surgical instruments + sterilise food killing bacteria
• as a tracer in body eg PET scans

Question 7

r

Answer 7

r

Question 8

r

Answer 8

r

Question 9

what are the dangers of radiation?

Answer 9

break molecules into ions which damage cells becoming cancerous or killed

a - dangerous inside, radiation absorbed by cells
b - dangerous outside, penetrate outer layer of skin, damages internal
g - if absorbed by cells but weakly ionising so can pass through body without damaging

Question 10

what is sievert?

Answer 10

measure of a radiations dose’s potential to harm a person

based on type + amount of radiation absorbed

Question 11

what is nuclear fusion?

Answer 11

if hydrogen nuclei brought close together, can fuse into helium nuclei which releases energy

fusion releases large amounts of energy + is the source of the suns power

Question 12

what does a nucleus contain?

Answer 12

positive protons and neutral neutrons held together by strong nuclear force which balances repulsive electrostatic force between protons

Question 13

explain nuclear energy?

Answer 13

energy released during nuclear fission greater than that released in a chem reaction involving a similar mass of material

Question 14

what is the equation for nuclear fusion/fission?

Answer 14

for mass of matter, M, the amount of energy, E, produced during nuclear fission given by:

E = mc2

Question 15

what is the alpha particle scattering experiment?

Answer 15

gold foil bombarded with alpha particles, effect on alpha particles recorded + observations provided evidence for our current understanding of atoms

Question 16

what 3 observations were recorded?

Answer 16

most alpha particles were seen to pass straight through gold foil:
- indicates gold atoms composed of large amounts of space

some particles were deflected + few bounced back towards source
- alpha particles passed close to some positively charged within atom and were repelled by it

Question 17

what were the conclusions of the experiment?

Answer 17

• nucleus positively charged
• electrons are arranged around the nucleus with great deal of space between them
• atoms consist of empty space with a nucleus

Question 18

what do nuclear power stations don’t do?

Answer 18

• don’t emit smoke from chimneys as happens in fossil fuel power stations
• don’t release greenhouse gases

Question 19

spent fuel rods from reactors in power stations do what?

Answer 19

• contain 90% uranium
• high level waste
• sent away to be reprocessed + used to make new rods

Question 20

how do you calculate half life?

Answer 20

used to calculate how old a radioactive substance is or how long it will take to become safe

Question 21

when is a substance considered to be safe?

Answer 21

once activity drops to same level as background radiation

some substances decay quick and could be safe in short time
those with long half life remain harmful for years

Question 22

how do you measure half life?

Answer 22

as radioactive atom decays, activity drops + radioactivity decreases
half life is time it takes for its radioactivity to 1/2

Question 23

why do experiments that measure half life need to be repeated?

Answer 23

need to be repeated + the activity level for each experiment averaged to give more reliable data bc there might be slight variations each time activity is measured

Question 24

what are elements?

Answer 24

made of atoms, each contains 1 type of atom + all atoms contain nucleus and electrons

Question 25

why is hydrogen different?

Answer 25

has no neutrons, just 1 proton + electron

Question 26

what are isotopes?

Answer 26

atoms of same element that have diff numbers of neutrons

Question 27

what are examples of when evert atom of a particular element has same number of protons?

Answer 27

hydrogen atoms - 1 proton
helium atoms - 2 protons
oxygen atoms - 8 protons

Question 28

when is ionising radiation emitted?

Answer 28

when nucleus of unstable atom decays, type of radioactive decay depends on why the nucleus is unstable

the process of decay helps atoms become more stable

Question 29

how alpha decay?

Answer 29

d

Question 30

how does beta decay?

Answer 30

d

Question 31

how does gamma decay?

Answer 31

d