What are Isotopes?
Nuclear physics
Same element, same number of protons but different number of neutrons.
Describe what a proton and nuclear number is.
Proton number (aka Atomic Number - Z).
This tells us the number of protons in the atom/nucleus
Nuclear number (aka Mass Number - A)
This tells us the number of protons and neutrons in the nucleus.
Why does radioactive decay happen?
Happens because of an imbalance between protons and neutrons.
Describe Alpha decay.
Symbol - 1H2
What is it - A helium nucleus (2 protons, 2 neutrons)
What can stop it penetrating power - thin sheet of paper or a few cm or air.
Ionising power - very high, most damaging in the body.
Describe Beta decay.
Symbol - 0β-1
What is it - Fast moving/high energy electron
What can stop it penetrating power - few mm of aluminium or up to a metre of air
Ionising power - medium
Describe Gamma decay
Symbol - γ
What is it - high energy electromagnetic waves
What can stop it penetrating power - several cm of lead or very thick concrete
Ionising power - low compared with alpha and beta. easily passes through the body
Describe an alpha decay equation.
222Rn86 > ?Po? + 4He2
222 - 4
86 - 2
?Po? = 218Po84
Rn is the parent nucleus
Po is the daughter nucleus
He is the alpha.
Describe an alpha decay equation.
General equation >
aXz > aY2+1 + 0β-1
e.g.
218Po84 > ?At? + 0β-1
= 218At85
Describe a gamma decay equation.
There’s none as Gamma just releases energy.
Describe sources of radiation.
Radioactive decay is RANDOM and SPONTANEOUS
This is why we need to
- take several readings to calculate the average
- measure over a longer period of time
