P2.5 What Happens when Radioactive Substances Decay and the Uses and Dangers of their Emissions

Question 1

If an atom of carbon has a mass number 14 and atomic number of 6 describe what this tells us about the number of electrons, neutrons and protons in the atoms?

Answer 1

6 protons.
8 neutrons.
6 electrons.

Question 2

What is meant by ionisation.

Answer 2

Loss or gain of electrons.

Question 3

State what an alpha and a beta particle are made up of.

Answer 3

Alpha - helium nucleus/ 2p +2n.

Beta - high speed electron.

Question 4

Which type of radiation is most ionising? Most penetrating?

Answer 4

Alpha.

Gamma.

Question 5

What is produced during the fission or Uranium 235?

Answer 5

Neutrons released are absorbed by other materials.
1 of the 2 neutrons released goes on to be absorbed by another uranium 235 nucleus.
Limiting the amount of energy released.

Question 6

Explain the difference between nuclear fission and nuclear fusion?

Answer 6

Nuclear fission - splitting of a large nucleus.

Nuclear fusion - joining of small nucleus.

Question 7

Describe the process whereby the energy from a nuclear reactor core is converted into electrical energy in 5 steps.

Answer 7

Heat energy transferred into a coolant which is usually water.
Super heated water is pumped to a heat exchanger where is it used to generate steam.
Steam turns a turbine which turns a generator.
Turns kinetic energy into electrical energy =.

Question 8

What problem is associated with the products of nuclear fission?

Answer 8

They’e radioactive.

Question 9

Define nuclear fusion.

Answer 9

The creation of large nuclei from smaller nuclei accompanied by the release of lots of energy.

Question 10

By what process do stars obtain their energy?

Answer 10

Nuclear fusion.

Question 11

Why does nuclear fusion only happen at temperatures and pressures?

Answer 11

To overcome the electrostatic repulsion of protons.

Question 12

What are the 2 main dangers if ionising radiation?

Answer 12

Tissue damage.

Possible mutations in DNA.

Question 13

Thorium and radium used to be put in face creams back in the 1900s. Why is this no longer done?

Answer 13

Scientists became aware of the hazards and risks.

Question 14

How can nuclear waste be disposed of and stored in the long term?

Answer 14

Stored in concrete,

Steel and glass containers.

Question 15

What is the main advantage of nuclear power over fossil fuelled power stations?

Answer 15

No CO2 released.

Question 16

What is the advantage of storing nuclear waste in space or sea?

Answer 16

Containers could fall back to earth.

Containers could corrode and leak.

Question 17

A substance has a half life of 2 days and an initial activity of 4000cps. What will its activity be after 6 days

Answer 17

500cps = 2 days.
2000cps = 4 days

Question 18

What do we mean by an isotope’s half life?

Answer 18

Time taken for the activity of a sample to half or time for half the undecayed nuclei to decay.

Question 19

What is meant by background radiation and where does it originate?

Answer 19

The natural radiation level around us from space, ground and rocks.
Radon gas.

Question 20

How is radiation used to gauge the thickness of paper?

Answer 20

Detector counts the rate at which beta particles pass through paper.
If it is too high or too low the paper isn’t the right thickness.

Question 21

How is radiation used in smoke alarms?

Answer 21

Alpha particles from AMERCIUM-241 ionise the air to make ions and electrons.
A current flows between 2 charged plates.
When smoke gets in the air gaps the current falls and sounds the alarm.

Question 22

How are stars formed?

Answer 22

Stars form when dust and gas is pulled together by gravitation attraction.

Question 23

Explain why the early universe contained only hydrogen but now contains a large variety of different elements?

Answer 23

Elements other than hydrogen and helium were made in super novae.

Question 24

Describe the forces acting on a star during the main sequence period of its life?

Answer 24

It is stable because the forces within it are balanced.

Gravity is balanced by pressure within the star.

Question 25

Describe the stages of a smaller star.

Answer 25

Nebulae.
Star.
Red giant.
White dwarf.

Question 26

Describe the stages of a large star.

Answer 26

Nebulae.
Large star.
Super massive red giant.
Super nova.
Neutron star.
Black hole.