Radioactivity And Ionising Radiation Flashcards
(40 cards)
What is a proton
Realtime mass 1
Charge +1
What is a neutron
Mass 1
Charge 0
What is an electron
Mass 1/2000
Charge -1
What is alpha
A helium nucleus
Slow and heavy
Strongly ionising
Stopped by paper and skin
What is beta
An electron
Light and fast
Moderately ionising
Stopped by thin metals
What is gamma
Electromagnetic wave
No mass very fast
Weakly ionising
Stopped by thick lead or very thick concrete
What is a positron
It is an anti particle of an electron
Relative mass 1/2000
Charge +1
They have the same properties as an electron
If they meet an electron they are annihilated
What is neutron radiation
They are more penetrating than alpha beta or gamma
They’re not directly ionising but can be absorbed by nuclei of atoms in substances they pass through
Absorbing a neutron can make a nucleus radioactive
Neutrons are absorbed best by light nuclei such as hydrogen
Often neutron absorption makes nuclei emit gamma radiation
What makes a nucleus unstable
Too many neutrons
Too few neutrons
Too many protons and neutrons together
Too much energy
What does the curve of stability show
Any isotope not on the curve is unstable
An isotope above the curve has too many neutrons to be stable
An isotope below the curve as too few neutrons to be stable
When does beta- decay happen
When there are too many neutrons
What happens in beta- decay
Emission of an electron from the nucleus
It happens when there’s more neutrons than protons so one of the neutrons is changed into a proton
The proton number is increased by one and the mass number stays the same
When does beta+ decay happen
When there are too few neutrons
What happens in beta+ decay
A positron is emitted from the nucleus
A proton gets changed into a neutron
So the proton number decreases by one and the mass number stays the same
When does alpha decay happen
When there are navy atoms with a z value (number of protons) above 82 like uranium and radium
What happens is alpha decay
A helium nucleus is emitted
The proton number decreases by two and the mass number decreases by four
When does gamma radiation happen
After alpha or beta decay the nucleus has lots of energy
What happens in gamma radiation
It always goes with alpha or beta decay there’s no change in the proton on mass number of the atom
What are quarks
Small particles that make up protons and neutrons
Describe an up quark
Charge 2/3
Mass 1/3
Describe a down quark
Charge -1/3
Mass 1/3
What is a proton made up of
Two up quarks and one down quark
The charge is 2/3+2/3+{-1/3} = 1
The mass is 1/3+1/3+1/3=1
What is a neutron made up of
One up quark and two down quarks
Charge is 2/3 +{-1/3}+{-1/3}
Mass is 1/3+1/3+1/3
What happens when a neutron is turned to a proton
A down quark turns into an up quark
The overall charge still has to be 0 so an electron is also produced
