Transcript Nuclear Radiation

Nuclear Radiation
Radioactivity
As the heavier atoms become
more unstable, particles and
photons are emitted from the
nucleus and it is said to be
radioactive. All elements with
Atomic # greater than 82 are
radioactive.
a
bb+
g
Alpha particles a
b- particles (electrons)
Gamma rays g
(sometimes positrons)
The Alpha Particle
An alpha particle a is the nucleus of a helium
atom consisting of two protons and two
neutrons tightly bound.
Relatively low speeds
Not very penetrating
The Beta-minus Particle
A beta-minus particle b- is simply an electron
that has been expelled from the nucleus.
-
High speeds
Very penetrating
The Gamma Photon
A gamma ray g has very high electromagnetic
radiation carrying energy away from the
nucleus.
g
g
g
Very fast
g
Most penetrating radiation
Radioactive Decay
If the ratio of neutrons/protons gets very large,
the nucleus becomes unstable and often particles
and/or photons are emitted.
.
4
2
a
The half-life T1/2 of
an isotope is the
time in which onehalf of its unstable
nuclei will decay.
1
N  N0  
2
n
Where n is number
of half-lives
Number Undecayed Nuclei
The Half-Life
No
N0
2
N0
4
1 2 3 4
Number of Half-lives