P2.5 What Happens when Radioactive Substances Decay and the Uses and Dangers of their Emissions Flashcards
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?
6 protons.
8 neutrons.
6 electrons.
What is meant by ionisation.
Loss or gain of electrons.
State what an alpha and a beta particle are made up of.
Alpha - helium nucleus/ 2p +2n.
Beta - high speed electron.
Which type of radiation is most ionising? Most penetrating?
Alpha.
Gamma.
What is produced during the fission or Uranium 235?
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.
Explain the difference between nuclear fission and nuclear fusion?
Nuclear fission - splitting of a large nucleus.
Nuclear fusion - joining of small nucleus.
Describe the process whereby the energy from a nuclear reactor core is converted into electrical energy in 5 steps.
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 =.
What problem is associated with the products of nuclear fission?
They’e radioactive.
Define nuclear fusion.
The creation of large nuclei from smaller nuclei accompanied by the release of lots of energy.
By what process do stars obtain their energy?
Nuclear fusion.
Why does nuclear fusion only happen at temperatures and pressures?
To overcome the electrostatic repulsion of protons.
What are the 2 main dangers if ionising radiation?
Tissue damage.
Possible mutations in DNA.
Thorium and radium used to be put in face creams back in the 1900s. Why is this no longer done?
Scientists became aware of the hazards and risks.
How can nuclear waste be disposed of and stored in the long term?
Stored in concrete,
Steel and glass containers.
What is the main advantage of nuclear power over fossil fuelled power stations?
No CO2 released.
What is the advantage of storing nuclear waste in space or sea?
Containers could fall back to earth.
Containers could corrode and leak.
A substance has a half life of 2 days and an initial activity of 4000cps. What will its activity be after 6 days
500cps = 2 days. 2000cps = 4 days
What do we mean by an isotope’s half life?
Time taken for the activity of a sample to half or time for half the undecayed nuclei to decay.
What is meant by background radiation and where does it originate?
The natural radiation level around us from space, ground and rocks.
Radon gas.
How is radiation used to gauge the thickness of paper?
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.
How is radiation used in smoke alarms?
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.
How are stars formed?
Stars form when dust and gas is pulled together by gravitation attraction.
Explain why the early universe contained only hydrogen but now contains a large variety of different elements?
Elements other than hydrogen and helium were made in super novae.
Describe the forces acting on a star during the main sequence period of its life?
It is stable because the forces within it are balanced.
Gravity is balanced by pressure within the star.
Describe the stages of a smaller star.
Nebulae.
Star.
Red giant.
White dwarf.
Describe the stages of a large star.
Nebulae. Large star. Super massive red giant. Super nova. Neutron star. Black hole.
