radioactivity

Question 1

what is the structure of an atom?

Answer 1

a positively charged nucleus which contains positive protons and neutral neutrons, negatively charged electrons on the outer shells

Question 2

what are the masses and charges of these:
- proton:
- neutron:
- electron:

Answer 2

proton: mass= 1 charge= +1
neutron: mass= 1 charge= 0
electron: mass= 1/1826 charge= -1

Question 3

what is an isotope?

Answer 3

atom with the same number of protons, but different number of neutrons

Question 4

when electrons move to a higher orbit (away from the nucleus), what happens to the EM radiation?

Answer 4

the atom absorbs the EM radiation

Question 5

when electrons move to a lower orbit (closer to the nucleus), what happens to the EM radiation?

Answer 5

the atom emits EM radiation

Question 6

what are the 4 forms of decay?

Answer 6

• alpha
• beta minus
• beta plus
• gamma

Question 7

how ionising are these?
- alpha
- beta minus
- beta plus
- gamma

Answer 7

• alpha: highly ionising
• beta minus: medium ionising
• beta plus: medium ionising
• gamma: low ionising

Question 8

how penetrating (able to get through things) are these?
- alpha
- beta minus
- beta plus
- gamma

Answer 8

• alpha: weakly penetrating
• beta minus: medium penetrating
• beta plus: medium penetrating
• gamma: highly penetrating

Question 9

what are 3 examples of background radiation?

Answer 9

• cosmic rays
• medical rays
• radiation from underground rocks

Question 10

what is one way of measuring radioactivity and how is it used?

Answer 10

geiger-muller tube, a tube that can detect radiation, it absorbs radiation and transmits an electrical pulse to the machine creating a clicking sound, the more clicks the more radiation present

Question 11

what did Dalton say about atoms?

Answer 11

he said everything is made of atoms

Question 12

what did jj thomson discover and what model did he form?

Answer 12

he discovered the electron and made the plum pudding model

Question 13

what is the theory of the plum pudding model?

Answer 13

jj thompson said the overall charge of an atom is neutral so he created a circle of positive charge and placed negative electrons on it

Question 14

what did Rutherford realise and what experiment did he use?

Answer 14

he realised most of the atom is empty space and he used the gold foil experiment

Question 15

what is the Rutherford model?

Answer 15

there is a positive nucleus in the centre of an atom and the electrons are distributed in the space around the nucleus

Question 16

who produced the final model of the atom and what is it?

Answer 16

Bohr produced the final model and he concluded that the electrons exist in fixed orbits around the nucleus

Question 17

what is half life?

Answer 17

the time taken for half the nuclei to decay

Question 18

what are 3 uses of radioactivity?

Answer 18

• smoke alarms
• diagnosis/treatment of cancer
• sterilise equipment

Question 19

what safety precautions do medical doctors need to take when undergoing radioactive tests?

Answer 19

they should leave the room as it puts their health at risk in the long term

Question 20

what are the two ways radiation can treat tumours ?

Answer 20

external and internal

Question 21

what is the external treatment of tumours and how effective is it?

Answer 21

where a beam of gamma radiation rotates around the body, mainly focuses on the tumour but can sometimes pass the healthy cells
effectiveness: takes a long time to fully treat the tumour, greater risk of long term side effects as radiation passes through healthy cells

Question 22

what is the internal treatment of tumours and how effective is it?

Answer 22

patient injected with radioactive material directly onto the tumour
effectiveness: doesn’t affect the healthy cells around, however a long time is to be spent in hospital as the patient will have high radioactivity and can emit radiation so limited contact is to be made

Question 23

how do PET scanners work?

Answer 23

• a radioactive tracer is inserted into the body
• the scanner records where the tracer emits radiation
• this produces an image of the body

Question 24

what are PET scanners used for?

Answer 24

• they are used to show how effective treatment is
• to diagnose cancer

Question 25

what is radioactive decay?

Answer 25

when an unstable nucleus splits into two smaller nuclei

Question 26

what is nuclear fusion?

Answer 26

where multiple nuclei’s fuse together to make one leading to a release of energy through heat, sound, light