radioactivity Flashcards
What type of radiation is most ionising?
alpha is most ionising but least penetrative
what is alpha radiation?
A helium atom
What is beta radiation?
An electron
What is gamma radiation?
An electromagnetic wave
What are the four types of ionising radiation?
nuclear radiation, alpha, beta and gamma
A radioactive material has…
Unstable isotopes that can decay
What does an alpha particle consist of?
Two neutrons and two protons
What causes the emission of a neutron?
A nucleus has too many neutrons making it unstable
What type of radiation can penetrate paper and aluminium but not lead?
Gamma, it’s the least ionising but most penetrative
What type of radiation can penetrate paper but not aluminium?
Beta it’s moderately ionising and moderately penetrative
What type of radiation can’t penetrate paper?
Alpha
What is the source of a beta particle?
A neutron decaying into a proton and an electron
What is activity measured in?
Becquerels
What is half life?
The time taken for the activity to fall by half
what happens to something undergoing alpha decay?
The mass (top) number decreases by four and the atomic (bottom) number decreases by two because the mass number of a helium atom is 4 and the atomic number is two (lipgin)
What happens to something undergoing beta decay?
The mass (top) number stays the same and the atomic number increases by one (lipgin) because it’s adding an electron - charge -1
What happens to something undergoing gamma decay?
Nothing because gamma’s an em ray it has no charge
How is the activity of a sample measured?
Using a geiger muller counter
What is an isotope?
Atoms of the same element with a different number of neutrons
What is nuclear fusion?
The fusing of two lighter nuclei to make a single heavier nucleus
Where does the massive amount of energy released from nuclear fusion come from?
Some of the mass converts to energy
What conditions does nuclear fusion need?
Very high temperature and pressure
Why does nuclear fusion need high temperature and pressure?
To overcome the repulsion of the positively charged nuclei
What is nuclear fission?
The splitting of a large unstable nuclei into smaller nuclei
What kind of radiation do unstable nuclei release when they split?
Gamma
How do we help keep nuclear fission stable?
Put boron rods into the nuclear reactor which absorbs neutrons and slows down the reaction
How can nuclear fission occur?
By an atoms nuclei absorbing a neutron. This makes it more unstable and helps to split the nuclei
What is a chain reaction in terms of nuclear fission?
When a neutron is fired at an u stable nucleus, the nucleus splits into two daughter nuclei and a couple of neutrons. These neutrons are absorbed by other unstable nuclei and the process repeats over and over
How do nuclear power stations generate electricity?
When unstable nuclei split they release gamma radiation which heats water and turns it to steam. The steam rises and turns turbines and the kinetic energy of the turbines is converted to electricity by a generator
How do we keep nuclear reactors safe?
Lower boron rods into the nuclear reactor which absorbs neutrons and slows down the chain reaction
What form is energy emitted in during nuclear fusion?
Electromagnetic radiation
Where does nuclear fusion happen?
Im stars, why they’re so bright and hot
