Radioactivity and particles

Question 1

What does an atom consist of

Answer 1

• positively charged nucleus
- protons
- neutrons
• surrounded by electrons, which orbit the nucleus

Question 2

Define mass number

Answer 2

number of protons + number of neutrons

Question 3

define atomic number

Answer 3

number of protons

Question 4

define isotopes

Answer 4

forms of same element that has same number of protons but different number of neutrons

Question 5

define radioactive decay

Answer 5

• spontaneous emission of nuclear radiation by an unstable nucleus to become stable
• random process

Question 6

describe the nature of alpha particles

Answer 6

• positively charged
• similar to helium nucleus
• high ionizing power
• low penetration
• blocked by thin sheet of paper

Question 7

describe nature of beta particles

Answer 7

• negatively charged
• similar to fast-moving electron
• medium ionizing power
• medium penentration
• blocked by an aluminum sheet

Question 8

describe nature of gamma radiation

Answer 8

• neutral charge
• electromagnetic radiation
• low ionizing power
• high penetration
• blocked by lead block

Question 9

practical: investigation ethe penetration powers of different types of radiation

Answer 9

1. Connect GM detector to counter and remove the source and measure background radiation over period of time (eg 1 minute)
2. repeat 3 times and get an average
   3.replace the source and place different materials between the source and detector and record count rate for each 3 times and find mean
   4.repeat experiment with different sources

if count rate stays same = radiation can penetrate material
if count rate drops by large amount = radiation is blocked
if count rate is zero = radiation is completely absorbed

Question 10

effects on atomic and mass numbers of anucleus of the emmision of four types of radiation

Answer 10

alpha
• mass = decrease by 4
• atomic = decrease by 2

beta
• mass = stays same
• atomic = increase by 1

gamma
• mass = stays same
• atomic = stays same

neutron
• mass = decrease by 1
• atomic stays same

Question 11

How to detect ionizing radiations

Answer 11

• GM detector
• photographic film

Question 12

Explain sources of background radiation

Answer 12

earth
• air
• food
• buildings
• rocks

space
• cosmic rays

Man made sources
• nucleur waste
• nucleur fallout

Question 13

What do you measure radioactivity in

Answer 13

becquerels

Question 14

define half life

Answer 14

time taken for half the radioactive atoms in a sample to decay

Question 15

describe the uses of radioactivity in industry and medicone

Answer 15

industry
• smoke detectors
• thickness monitoring

medicine
• sterilizing equipment
• diagnosis and treatment

Question 16

describe the difference between contamination and irradation

Answer 16

irradation means the object is exposed to radioactivity, while contamination means it is on the object.