Atomic structure

Question 1

how do electrons jump up energy levels

Answer 1

they become excited from the energy they get from em radiation

Question 2

how is em radiation emitted in an atom

Answer 2

when an excited atom falls back down to a lower energy level emitting the energy as em radiation

Question 3

the mass number is……….
the atomic number is………..

Answer 3

the mass number is the protons+neutrons and is at the top

the atomic number is the number of protons and is at the bottom

Question 4

what is ionisation

Answer 4

Electrons can also absorb enough energy to leave the atom altogether, this is known as ionisation

Question 5

what do unstable isotopes do

Answer 5

radioactive decay where they emit something to become more stable

Question 6

what are the 4 types of nuclear radiation

Answer 6

alpha
beta
gamma
neutrons

Question 7

what are alpha particles made up of and what is this the same as

Answer 7

2 protons and 2 neutrons same as nucleus of a helium atom

Question 8

what are the properties of alpha particles

Answer 8

large
have 2+ charge
least penetrative-stopped by few cm in air or single sheet of paper
-heavily/most ionising

Question 9

what does ionising mean

Answer 9

how easily something knocks off electrons off atoms it collides with

Question 10

what is the charge of beta particles

Answer 10

-electrons
-charge of -1 with little mass

Question 11

what are the properties of beta

Answer 11

-small
-moderately ionising and penetrative(stopped by several m of air /5mm of aluminium to stop

Question 12

how are beta particles formed

Answer 12

neutron decays to a proton and electron which gets emitted at high speed

Question 13

what are gamma rays and how are they emitted

Answer 13

not particles but em waves that are emitted after alpha and beta radiation as a way of releasing energy

Question 14

what are the properties of gamma rays

Answer 14

-they have no mass or charge so highly penetrative(stopped by thick sheets of lead or multiple m of concrete to stop)
-weakly ionising

Question 15

how are neutrons emitted

Answer 15

if a neutron is making a nucleus unstable it throws out the neutron to make it more stable

Question 16

what is the equation for alpha decay

Answer 16

loses 4 to the mass number and 2 atomic number

Question 17

what is the equation for beta decay

Answer 17

0 to the mass number +1 to the atomic number

Question 18

what is the equation for neutron emission

Answer 18

+1 to the mass number

Question 19

what is the activity

Answer 19

overall rate of decay of all the isotopes in our sample
measured in bq where 1 bq =1 decay per second

Question 20

what is half life

Answer 20

time taken for no of decays(activity)to half

Question 21

what is the count rate

Answer 21

the no of decays counted by a geiger muller counter

Question 22

what is irradiation

Answer 22

when objects are exposed to any type of radiation

Question 23

what is contamination

Answer 23

when radioactive particles get onto other objects

Question 24

what is the harm of contamination

Answer 24

the radioactive material you are contaminated with is likely to decay and irradiate you

Question 25

why is ionising radiation most dangerous

Answer 25

can enter living cells and interact with molecules inside this involves dna which they can ionise and cause genetic mutation in rare cases can cause cancer

Question 26

what 3 things affect dosage

Answer 26

-distance from the source -how radioactive the material is -how long you are exposed to it

Question 27

how do we minimise irradiation and avoid contamination when we are around radioactive source

Answer 27

precautions like -wearing protective gear like gloves and overalls -handling item with tongs or tools -keeping item in lead lined box

Question 28

what is the only way you can spread radiation

Answer 28

by holding a radioactive source

Question 30

what causes radiation sickness and what symptoms does it have

Answer 30

recieving large doses of radiation across the entire body which will cause vomiting tiredness or hair less making you ill as most of your cells are killed or damaged

Question 31

how can radiation treat cancer and what is this called

Answer 31

can be used by doctors to destroy can cer cells called radiotherapy

Question 32

what are the 2 ways in radiotherapy that the radioactive source is delivered

Answer 32

externally or internally

Question 33

what is the difference between external and internal radiation

Answer 33

-external is performed by emitting gamma rays targetted at cancer site at different angles so it gets the highest dose -internal is performed with beta where it is placed next to or inside cancer

Question 34

what are the side effects of radiotherapy

Answer 34

kills other healthy cells in the body causing patients to feel sick

Question 35

how are medical tracers used

Answer 35

placing certain radioactive isotopes in a body by injection or swallowing by tracking the radiation they emit to see if certain organs are working by absorbing they right amount

Question 36

how do we minimise risk in treatments

Answer 36

use low dose with a short half life

Question 37

what is nuclear fission

Answer 37

splitting of unstable large nuclei into smaller nuclei and lots of energy

Question 38

what are the 2 ways nuclear fission can occur

Answer 38

-spontaneously-happens on its own(rare) -absorbing a neutron-makes nucleus less stable

Question 39

what are the steps of nuclear fission

Answer 39

1)fire slow moving neutron at unstable nuclei 2)it becomes less stable splitting apart into 2 daughter nuclei 2 or 3 neutrons and lots of energy in form of gamma radiation

Question 40

how does fission cause a chain reaction

Answer 40

the neutrons emitted can react with another unstable nuclei releasing huge amounts of energy(eg a nuclear bomb)-uncontrolled

Question 41

what are control rods and what role do they play in fission

Answer 41

control rate of fission which are lowered into reactor to absorb neutrons slowing down rate of reaction

Question 42

what is the energy from fission used for

Answer 42

heat up water turn it to steam drive turbines connected to an electricity generator

Question 43

what is nuclear fusion

Answer 43

when 2 light nuclei fuse to form single large nuclei and a lot of energy

Question 44

what has nuclear fusion done

Answer 44

fuels stars formed all elements heavier than hydrogen

Question 45

why is so much energy released in nuclear fission

Answer 45

some mass of original nuclei is transferred to energy as em radiation instead of new nucleus

Question 46

what are the pros/cons of nuclear fusion

Answer 46

pros no radioactive waste easily make the hydrogen needed as fuel cons -extremely high pressures and temperatures needed -cant be done on earth

Question 47

what are differences between fission and fusion

Answer 47

fusion-only happens inside stars fission-much less energy produced

Question 48

what is fusion inside stars

Answer 48

hydrogen fusing to become helium nuclei

Question 49

Why does fusion only happen at very high temperatures and pressures?

Answer 49

To overcome the repulsion of the positively charged nuclei