atomic structure

Question 1

what is radioactive decay

Answer 1

the process in which an unstable nucleus gives out radiation to become more stable

Question 2

what is alpha decay and what are the properties

Answer 2

2 protons and 2 neutrons (He)
- can’t penetrate very far
- strongly ionising

Question 3

what is beta decay and what are the properties

Answer 3

one of the atoms neutrons decay into a proton (stays in nucleus) and electron (which is emitted out)
- penetrate moderately far
- moderately ionising

Question 4

what is gamma waves and what are the properties

Answer 4

waves of electromagnetic radiation
no mass and no charge
- weakly ionising
- penetrating far

Question 5

explain the radiation of electrons

Answer 5

if the nucleus has too many neutrons it can increase the stability by getting rid of a neutron

Question 6

write the equation for alpha decay of radium 226 (atomic number 88)

Answer 6

226 222 4
ra ——- ? + He
88 86 2

Question 7

write the equation for beta decay of carbon 14 (atomic number 6)

Answer 7

14 14 0
C ——-? + e
6 7 -1

Question 8

write the equation for gamma radiation of radium 226 (atomic number 88)

Answer 8

226 226
ra ——— ra + gamma decay (y)
88 88

Question 9

is the decay process random or is there a specific pattern

Answer 9

random

Question 10

what is the activity of radioactive decay

Answer 10

overall rate of decay of all the isotopes in our sample ( measured in Bq)
1Bq = 1 decay per second

Question 11

define the two definitions of half life

Answer 11

• the time taken for the number of decays to half life
  OR
• the time taken for the number of radioactive nuclei in a sample to half

Question 12

what are the steps to calculate the half life

Answer 12

work out how many half lives
and then half the number of radioactive nuclei that many times

Question 13

the half life of a radioactive source is 40 hours, there are initially 3000000 radioactive nuclei in a sample. how many nuclei remain after five days

Answer 13

5 x 24 divided by 40 = 3 half lives

3000000/ 2 / 2 / 2 = 375000

Question 14

what is irradiation

Answer 14

the process by which objects are exposed to radiation

Question 15

what is contamination

Answer 15

when radioactive particles get onto other objects. if this radioactive material decays on you, your at risk of being irradiated

Question 16

which type of radiation is most harmful and why

Answer 16

ionising radiation are most harmful because they can interact with molecules inside cells.

Question 17

give an example of how radiation is harmful inside the body

Answer 17

if ionising radiation enters the cells, it can ionise DNA causing a mutation. this can cause them to divide uncontrollably possibly causing cancer

Question 18

what determines how harmful radiation is

Answer 18

location ( inside/ outside the body), the amount of radiation (dosage), how far away from the source, how long spent near the source, how radioactive it is

Question 19

what is background radiation

Answer 19

the radiation that is present all around in the environment

Question 20

what are the sources of background radiation

Answer 20

rocks, cosmic rays, nuclear weapon testing, nuclear accidents

Question 21

what are some uses of nuclear radiation in medicine

Answer 21

examining of internal organs
radiotherapy

Question 22

how are gamma rays used in raditheraphy

Answer 22

gamma emitters direct gamma rays at the cancerous cell, these cells absorb this radiation and the die

Question 23

how is beta radiation used in radiotherapy

Answer 23

the beta radiation is placed inside the body either next to or inside the cancerous cells in order for them to absorb the radiation and die

Question 24

what are the side effects of radiotherapy

Answer 24

• other cells also get damaged or killed
  why cancer patients feel so ill

Question 25

what are medical tracers used for and how are they used

Answer 25

to check if organs are working properly and diagnose diseases by tracking the movement of isotopes and the radiation they emit around the body

Question 26

why are gamma rays used in medical tracers and what dosage is given

Answer 26

they emit gamma radiation which has a shorted half life meaning radiation is only emitted for a shorter amount of time very small dosage

Question 27

what is nuclear fission and what are the two ways in which it occurs

Answer 27

the splitting of large and unstable nuclei into smaller nuclei spontaneously - fission is unforced and happens by itself absorbing a neutron - which splits a nucleus by making it even less stable

Question 28

explain the process of nuclear fission using uranium 235

Answer 28

1. start with a large unstable nuclei (uranium 235) and fire a slow moving neutron at at 2. this addition of a neutron makes it even less stable and causes it to split into two smaller nuclei (daughter nuclei) 3. this releases two or three more neutrons and loads of energy in the form of gamma radiation 4. the neutrons are then used again to from more daughter nuclei

Question 29

what are the consequences of an uncontrolled chain reaction of fission

Answer 29

the rate of fission is too high emitting too much energy resulting in a nuclear explosion

Question 30

how can nuclear fission be controlled

Answer 30

- control rods - absorb neutrons - slow down reaction - the energy released is used to heat up water, producing steam. this is then drive turbines which are connected to an electricity generator

Question 31

what are the pros and cons of nuclear energy

Answer 31

pros - uranium is relatively cheap, produces a large and steady amount of energy, doesn't produce greenhouse gasses cons -very expensive to build power plants, hard and expensive to dispose of as it has to be buried underground, risk of a major disaster if something malfunctions

Question 32

what is nuclear fusion

Answer 32

when two smaller / lighter nuclei fuse to make a single larger nuclei

Question 33

why does nuclear fusion create so much energy

Answer 33

some of the mass from the original smaller nuclei is converted to energy

Question 34

why is nuclear fusion good and what are the issues

Answer 34

doesn't produce radioactive waste easily make hydrogen which is needed as a fuel only happens at high pressures and temperatures

Question 35

where does nuclei fusion happen and why

Answer 35

inside stars because of the high temperatures and pressures