7b P1 radioactivity LM fission and fusion

Question 1

what happens when isotopes are unstable?

Answer 1

undergo radioactive decay, so they emit electrons

Question 2

what are alpha particles made up off?

Answer 2

2 protons and 2 neutrons, no electrons same as nucleus of Helium

Question 3

how do we represent alpha particles?

Answer 3

He or helium symbol

Question 4

what is the overall charge for alpha particles?

Answer 4

2+ because they have no electrons, and neutrons have a neutral charge

Question 5

how penetrating are alpha particles?

Answer 5

can’t penetrate far into other materials

• can only travel a few cm in air
• absorbed by a single sheet of paper

Question 6

how ionising are alpha particles?

Answer 6

very

- because of large size and strong charge

Question 7

what does strongly ionising mean?

Answer 7

easily knock electrons off of any atoms they collide with

Question 8

what are beta particles?

Answer 8

just an electron, charge of -1 and no mass

Question 9

how are beta particles made?

Answer 9

• one of the atoms neutrons decays into a proton and an electron
• proton stays in the nucleus, electron emitted at high speed

Question 10

how ionising are beta particles?

Answer 10

moderately

Question 11

how penetrating are beta particles?

Answer 11

penetrate moderately far

- several meters of air and 5mm of aluminium to stop them

Question 12

what are gamma rays?

Answer 12

waves of electromagnetic radiation

Question 13

when are gamma rays emitted?

Answer 13

often emitted after alpha or beta radiation, a way of getting rid of a bit of extra energy

Question 14

how penetrating are gamma rays?

Answer 14

penetrate really far

• long distances
• thick sheets of lead
• meters of concrete to stop them

Question 15

how ionising are gamma rays?

Answer 15

weakly because they have no mass or charge

Question 16

what is the last type of radiation?

Answer 16

emission of a neutron

Question 17

what happens to an atom that has too many neutrons?

Answer 17

wants to become stable so it throws out a neutron to increase stability

Question 18

what happens in an alpha decay ?

Answer 18

when an unstable nucleus undergos alpha decay, it emits an alpha particle
- have to subtract 4 from mass number
- subtract 2 from atomic number
the nucleus will change and then it will most likely become something else

Question 19

what happens in beta decay?

Answer 19

neutron turns into a proton and emits a beta particle

• gains a proton so atomic number changes (changes element as well)
• mass number stays the same
• e (beta particle) has an -1 and a 0

Question 20

why does the mass number in beta decay stay the same?

Answer 20

gained a proton, but it also lost a neutron

Question 21

what happens in gamma radiation and the equation?

Answer 21

if an element underwent gamma radiation it stays the same plus gamma radiation (weird v thing)

Question 22

what is the equation for neutron emission?

Answer 22

subtract one from the mass number of the element , and a neutron on the end

Question 23

what is a half life?

Answer 23

• the time taken for the number of radioactive nuclei in a sample to halve
• the take time for the number of decays or activity to halve
  both are correlated

Question 24

what is the activity in terms of decay?

Answer 24

overall rate of decay of all the isotopes in our sample

Question 25

what is activity measured in?

Answer 25

becquerels

1Bq = 1 decay per second s

Question 26

how do you know when a particle will decay?

Answer 26

you don’t, you can’t tell its completely random

Question 27

as the number of particles decrease…

Answer 27

the overall rate of decay or activity also decreases

Question 28

the half life of a radioactive source is 40 hrs, there are initially 3,000000 radioactive nuclei in the sample. how many nuclei will remain after 5 days?

Answer 28

1. how many half lives?
   5days x 24 hrs
   = 120 /40h = 3 half lives
2. halve the no. of nuclei that many times.
   so just half the initial number of radioactive nuclei three times because there are three half lives

Question 29

what is contamination?

Answer 29

when radioactive particles get onto other objects

Question 30

what is irradiation?

Answer 30

the process by which objects/things are expose to radiation of any type

Question 31

what are non ionising radiation ways?>

Answer 31

ultraviolet

and microwave

Question 32

why is contamination harmful?

Answer 32

isn’t but the particle on you is likely to decay and then irradiate the object, its the risk that is the issue

Question 33

what determines how harmful radiation is?

Answer 33

• what type
• where is the exposure
• the amount

Question 34

what are the more harmful types of radiation?

Answer 34

ionising, because they can enter living cells and interact with the molecules inside, ionise our DNA, that cause mutations

Question 35

what is the most harmful type of radiation when the source is outside the body?

Answer 35

beta and gamma because they can penetrate

Question 36

what is the most harmful type of radiation when the source is on or inside the body?

Answer 36

alpha is the most because it would make it to cells inside the body

Question 37

what precautions can reduce your risk of being contaminated or irradiated?

Answer 37

gloves
overalls
using tongs
keeping item in lead lined box

Question 38

what are the uses of radiation in medicine?

Answer 38

radiotherapy 
medical traces (X-rays etc)

Question 39

what is radiotherapy?

Answer 39

to destroy particular cells, mainly cancerous cells

Question 40

what are the two types of radiotherapy?

Answer 40

externally and internally

Question 41

how does external radiotherapy work?

Answer 41

gamma rays are targeted at the cancer site at lots of different angles
cancer site gets the highest dose

Question 42

how does internal radiotherapy work?

Answer 42

beta rays