An unstable atomic nucleus emits a form of radiation
(alpha, beta, or gamma) to become stable.
In other words, the nucleus decays into a different
Atoms and Radioactivity
Isotopes of some elements have unstable nucleus .In
order to become stable the make break apart or decay
.This decay causes the nucleus to emit ionising
radiation, and an atom of a different element is
formed . These isotopes are called radioisotopes or
Example – using Carbon
A normal carbon
nucleus looks like this,
it has 6 protons and 6
neutrons. This is
It is actually the nucleus of a helium atom consisting of 2 protons and
2 neutrons, held tightly together.
It comes directly from the nucleus, so only big atoms tend to emit it.
It strongly interacts with matter around it, smashing past atoms and
The alpha radiation, a helium
nucleus (2,protons and 2
Is a high speed electron, given off when a neutron turns
into a proton
They are many times smaller than alpha radiation
They interact much less strongly with matter
Beta radiation, (a high speed electron)
Sometimes a nucleus that is still unstable after a beta or alpha decay
is still unstable so may emit gamma radiation to become more stable.
This is an electromagnetic wave with a very short wavelength
It does not change the number of protons or neutrons in the nucleus
The decay process is random.
No one can predict when 1 nucleus decays.
The emission is spontaneous.
It is possible to make a statistical prediction.
Betas and gammas are the most dangerous
they can penetrate and reach the cells of organs
They are absorbed and ionise the cells
This can cause cancer
Alphas are the least dangerous
The gamma rays they
emit can travel long
This has been caused by long exposure to gamma
Alpha radiation is the most dangerous as it
is strongly absorbed and ionises cells
Betas and gammas are not strongly
absorbed and cause less ionisation damage
Gamma rays are used to kill
cancer cells and bacteria
Sterilization of hospital equipment
Checking leaks in pipes
Irradiation of food