Particle

Question 1

Observations of alpha scattering experiment

Answer 1

• most of the mass in one small volume
• nucleus is positively charged ( they repel positively charged alpha particles)
• negative electrons orbit the nucleus at a large distance from it (negative charges needed to keep atom neutral)

Question 2

what is ionisation

Answer 2

the removal of one or more electron from an atom.

Question 3

Alpha fact file
ionising power:
Uses:
Danger out of body:
Danger in body:
penetrating power:
stopped by:
Charge:
range in air:
deflection by em field

Answer 3

-high
- smoke detectors, radiotherapy cancer
- low
- cell death,mutation,cancer
- low
- paper n skin
- +2
- 5cm
- yes

Question 4

Beta fact file
ionising power:
Uses:
Danger out of body:
Danger in body:
penetrating power:
stopped by:
Charge:
range in air:
deflection by em field:

Answer 4

• medium
• thickness control in paper
• damage to skin
• same as alpha but less damage
• medium
• aluminium
• -1
• 2-3m
• yes

Question 5

Gamma fact file
ionising power:
Uses:
Danger out of body:
Danger in body:
penetrating power:
stopped by:
Charge:
range in air:
deflection by em field:

Answer 5

• low
• tracers + sterilising medical equipment
• cell death mutation and cancer
• low
• high
• lead and concrete
• 0
• 15m
• no

Question 6

charge of alpha

Answer 6

+2e

Question 7

alpha decay calculations

Answer 7

top minus 4
bottom minus 2

Question 8

why and how does beta decay happen

Answer 8

caused by the weak nuclear force. radioactive nuclei that emits beta -minus radiation characterised as having too many neutrons for stability.weak nuclear force causes one of the neutrons decaying to a proton. an electron and electron anti-neutrino is emitted.

Question 9

why does beta plus decay happen

Answer 9

too many protons for stability. weak nuclear force inititates changes within parent nucleus by neutron transforming one of the protons into a neutron.

Question 10

beta plus decay

Answer 10

proton becomes a neutron. postiron, electron neutrino emitted.
bottom no. -1 + 0-1e + Ve

Question 11

why and how does gamma decay happen

Answer 11

gamma photons emitted if nucleus has surplus energy following an alpha or beta emission.

stays the same + gamma photon

Question 12

why is radioactive decay random

Answer 12

• can’t predict when the next one will be
• each nucleus has the same chance as decaying per unit time

Question 13

why is radioactive decay spontaneous

Answer 13

• because its not affected by presence of other nuclei in the sample
• external factors such as pressure

Question 14

half life definition

Answer 14

the average time it takes for half the number of active nuclei in the sample to decay.

Question 15

activity definition

Answer 15

the rate at which nuclei decay or disintegrates.

Question 16

activity definition emission

Answer 16

the number of alpha beta or gamma photons emitted from the source per unit time.

Question 17

bequerel defintion

Answer 17

activity of one decay per second.

Question 18

decay constant definition

Answer 18

probability of decay of an individual nucleus per unit time.

Question 19

what is directly proportional

Answer 19

activity A to N number of undecayed nuclei