Atomic structure

Question 1

Alpha

Answer 1

2 neutrons and 2 protons (same as helium nucleus)
- absorbed by paper
- large so cant penetrate very far for other materials
- strongly ionising : easily knock electrons off any atoms they collide with

Question 2

Beta

Answer 2

High speed electron
Emitted when a neutron turns into a proton in nucleus
tiny so moderately ionising
penetrate moderately far in materials

Question 3

Gamma

Answer 3

Only stopped by a few cm of lead
Very penetrating
EM radiation
pass straight through materials (as no charge/mass) so weakly ionising
penetrate really far through materials before being stopprd

Question 4

Plum pudding Model

Answer 4

Ball of positive charge with negative charges scattered throughout

Question 5

Uses of Nuclear Radiation

Answer 5

Medical tracers:
- use to detect its radiation
- radioactive tracer is consumed and targets a part of the body
- have short half- lives

Destroying unwanted tissue:
- gamma rays can be focused onto areas of the body and kill unwanted cells

Question 6

Bohr Model

Answer 6

Central nucleus, electrons in energy levels orbiting it

Question 7

Half- Life

Answer 7

time for number of unstable nuclei in a given isotope to halve

Question 8

Count-rate

Answer 8

measured using a Geiger- Muller tube

Question 9

Activity

Answer 9

rate at which a nuclei decays

Question 10

Nuclear fusion

Answer 10

joining of two light nuclei into a large nucleus
- mass in converted into energy in the form of radiation

Question 11

Nuclear Fission

Answer 11

splitting of large and unstable nuclei
unstable nuclei must absorb a slow-moving neutron
- produces two smaller nuclei and releases energy
- releases two or three neutrons
- once released, induce further fission

Question 12

Irradiation

Answer 12

process by which objects are exposed to radiation

Question 13

Contamination

Answer 13

when radioactive particles get onto other objects

Question 14

What determines how harmful radiation is?

Answer 14

• the amount
• type of radiation
• where your exposed to it

Question 15

How do you minimise irritation?

Answer 15

• take precautions
• gloves
• overalls
• tongs
• lead lined box

Question 16

Medical tracers

Answer 16

• radioactive isotope is injected or swallowed by a person
• if the tracer is injected, the trace moves to part of body through blood
• tracer is swallowed - absorbed through persons intestine to the bloodstream
• position of tracker is detected from outside the body- emits radiation
• see : movement and accumulation of the tracer in the body