Radioactivity

Question 1

What is the diameter of an atom

Answer 1

10^-10 m

Question 2

What is the relative mass of an electron

Answer 2

1/1840 compared to neutron/proton

Question 3

Define isotopes

Answer 3

Isotopes are atoms of the same element that have same number of protons but different number of neutrons

Question 4

Define nuclear decay/radioactivity

Answer 4

Nuclear decay is a spontaneous and random process by which unstable nucleus loses energy by emission of electromagnetic radiation or particles

Question 5

What does nuclear decay being spontaneous refer to

Answer 5

It is not possible to speed up, slow down, start or stop the process of radioactive decay by artificial means

Question 6

What does nuclear decay being random process refer to

Answer 6

It is not possible to predict when nucleus will decay/emit radiation or in which direction the radiation will be emitted

Question 7

Describe alpha particles
(What is it, ionising effect, penetrating power)

Answer 7

Helium nucleus (2 protons and 2 neutrons) which have net positive charge
Highest ionising effect
Lowest penetrating power - stopped by piece of paper, human skin

Question 8

Describe beta particles
(What is it, ionising effect, penetrating power)

Answer 8

High energy electron
Medium ionising effect
Medium penetrating power - stopped by piece of aluminium few mm thick

Question 9

Describe gamma rays
(What is it, ionising effect, penetrating power)

Answer 9

Electromagnetic waves of high energy and frequency
Lowest ionising effect
Highest penetrating power - stopped by few cm thick lead or very thick concrete

Question 10

Define ionising radiation

Answer 10

Radiation with high energies that can knock off electrons from atoms to form ions

Question 11

Define background radiation

Answer 11

The nuclear radiation in an environment where no radioactive source has been deliberately introduced

Question 12

How to measure ionising radiation

Answer 12

Measured using Geiger-Muller (GM counter)
SI unit is Becquerel

Question 13

Define half life

Answer 13

The time taken for half the nuclei of that nuclide in any sample to decay

Question 14

What are applications of radioactivity related to damage of cells

Answer 14

Medical treatment of cancers (from em waves)
Sterilisation of food and medical equipment

Question 15

What are applications of radioactivity related to radioactive decay and half-life

Answer 15

Radiocarbon dating- all living things contain carbon and amount of carbon-14 makes them slightly radioactive. By measuring proportion of carbon-14, researchers can find time of death
Uranium-lead dating (measure uranium-238)

Question 16

What are applications of radioactivity related to penetrating ability

Answer 16

Radioactive tracers and thickness control

Question 17

What are hazards of radioactivity (same as EM waves)

Answer 17

Damage biological molecules, living cells and tissues. It can lead to cell death, mutations and abnormal cell division. Overexposure can cause immediate effects like pain and radiation burns, leading to sores and blisters and cancers such as leukaemia or deformities to developing foetus

Question 18

What factors determine hazards of radioactivity

Answer 18

Half-life of radioactive materials
Penetrating abilities of radioactive emissions
Ionising effects of radioactive emissions

Question 19

What precautions can be taken to prevent hazards of radioactivity

Answer 19

Reduce exposure time, increase distance between source and living tissue, shielding by using materials that absorb ionising radiation(lead-lined gloves and suits), proper storage and disposal(lead box)

Question 20

Define nuclear fission

Answer 20

Nuclear fission is a process in which the nucleus of an atom splits and releases a huge amount of energy

Question 21

Define nuclear fusion

Answer 21

Nuclear fusion is a process in which two light atomic nuclei combine to form one heavier atomic nucleus and release a huge amoutn of energy