Chapter 8 - Radioactivity

Question 1

Who discovered uranium and when?

Answer 1

Henri Becquerel discovered it in 1896 during a photographic experiment

Question 2

Who discovered Polonium and Radium?

Answer 2

Pierre and Marie Curie

Question 3

What are the three types of radioactivity?

Answer 3

Alpha particles α
Beta particles β
Gamma radiation γ

Question 4

Radiation

Answer 4

The spontaneous breaking up of unstable nuclei with the emission of one or more types of radiation emitted from the nucleus of the unstable atom

Question 5

What is the composition of alpha particles?

Answer 5

Groups of two protons and two neutrons stuck together (same as a helium nucleus). They have a +2 charge

Question 6

Describe the penetrating power of alpha particles

Answer 6

They are heavy so have a low penetrating power and are stopped by a few centimetres of air or a sheet of paper

Question 7

Give a use of alpha particles

Answer 7

americium-241 in smoke detectors

Question 8

How are beta particles formed?

Answer 8

When a neutron in an unstable nucleus splits into a proton and an electron and the electron is released. They are simply fast moving electrons

Question 9

Describe the penetrating power of beta particles

Answer 9

They are lighter so travel faster than alpha particles. They can penetrate up to about 5mm of aluminium

Question 10

Give a use of beta particles

Answer 10

carbon-14 used in carbon dating

Question 11

What is gamma radiation?

Answer 11

High energy electromagnetic radiation released by an unstable nucleus to expel excess energy. Doesn’t consist of charged particles so is not deflected by electric/magnetic fields

Question 12

Describe the penetrating power of gamma rays

Answer 12

Very high penetrating ability and is only stopped by a thick slab of lead or concrete

Question 13

Give a use of gamma radiation

Answer 13

cobalt-16 is used in cancer treatment

Question 14

What instrument is used to detect radiation?

Answer 14

Geiger-Müller tube (Geiger counter)

Question 15

Nuclear reaction

Answer 15

Process that alters the composition, structure or energy of the atomic nucleus

Question 16

What are the differences between a chemical reaction and a nuclear reaction?

Answer 16

1. Chemical reaction involves electrons; nuclear reaction involves the nucleus
2. No new element is formed in a chemical reaction; a new element is formed in a nuclear reaction
3. There is no release of nuclear radiation in a chemical reaction; nuclear radiation is released with a nuclear reaction
4. In a chemical reaction chemical bonds are broken and formed; in a nuclear reaction there is no chemical bond breaking or formation

Question 17

Transmutation

Answer 17

The transformation of one element into another

Question 18

What happens when an atom loses an alpha particle?

Answer 18

It changes into an atom of the element two places before it in the Periodic Table, and the mass number of the parent atom decreases by four

Question 19

What happens when an atom loses an beta particle?

Answer 19

It changes into an atom of the element one place after it in the Periodic Table but the mass number of the parent atom stays the same

Question 20

What happens when an atom loses gamma radiation?

Answer 20

No new atom or element is formed, only energy is lost from the atom

Question 21

Half-life

Answer 21

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

Question 22

What is the half life of carbon-14?

Answer 22

5700 years

Question 23

What is the half life of cobalt-60?

Answer 23

5 years

Question 24

What is the half life of polonium-234?

Answer 24

0.15 miliseconds

Question 25

Radioisootpe

Answer 25

Radioactive isotope

Question 26

What are the medical uses of radioisotopes?

Answer 26

○Gamma rays penetrate the body and kill cancerous cells → radiotherapy
○Gamma rays are used to sterilise medical equipment by destroyed germs

Question 27

What are the archaeological uses of radioisotopes?

Answer 27

○Radiocarbon dating

○e.g Dead Sea Scrolls, 2000 years old

Question 28

Radiocarbon dating (carbon dating)

Answer 28

Technique used to determine the age of an object containing carbon. It is based on the ratio of carbon-14 to carbon-12 in the object

Question 29

What are the agricultural uses of radioisotopes?

Answer 29

○Used as trackers for the uptake of fertilisers → tracer studies

Question 30

What are the food uses of radioisotopes?

Answer 30

○Food irradiation

○Gamma rays kill bacteria which cause food to go off

Question 31

What are the industrial uses of radioisotopes?

Answer 31

○Leaks in pips are located by feeding a radioactive isotope through the pipe
○Test the ground above with a Geiger counter

Question 32

Give examples of radioactivity around us

Answer 32

○Rocks in the crust decay to release radioactivity
○Radon gas comes from the decay of Uranium or Thorium
○Plants take in radioactive material from the soil
○All called natural radioactivity or background radioactivity
○Nuclear weapons/accidents