2. CA Standards
Students know the three most common forms
of radioactive decay (alpha, beta, and gamma)
and know how the nucleus changes in each type
of decay.
Students know alpha, beta, and gamma
radiation produce different amounts and kinds
of damage in matter and have different
penetrations.
Students know some naturally occurring
isotopes of elements are radioactive, as are
isotopes formed in nuclear reactions.
4. Types of Radioactive Decay
alpha production (a, He): helium nucleus
238
92 U He
4
2
234
90 Th
beta production (b, e):
234
90 Th 234
91 Pa e
0
1
gamma ray production (g):
U He
238
92
4
2 Th 2 g
234
90
0
0
5. Nuclear
Stability
Decay will occur in
such a way as to
return a nucleus to
the band (line) of
stability.
6. Alpha
Radiation
Alpha decay is
limited to VERY
large, nuclei
such as those in
heavy metals.
8. Alpha Particle Beta Particle Gamma Ray
Emission Emission Emission
4
Symbol 2 He 2 or 2 a 2
4 0
1 e 0
or 1 b
0
0 g
Mass Heavy Light No Mass
How it changes Decreases the Converts a No change to the
the nucleus mass number neutron into a nucleus
by 4 proton
Decreases the Increases
atomic number atomic number
by 2 by 1
Penetration Low Medium High
Protection Skin Paper, clothing Lead
provided by…
Danger Low Medium High
9. CA Standards
Students know protons and neutrons in the
nucleus are held together by nuclear forces
that overcome the electromagnetic repulsion
between the protons.
Students know the energy release per gram of
material is much larger in nuclear fusion or
fission reactions than in chemical reactions.
The change in mass (calculated by E = mc2) is
small but significant in nuclear reactions.
11. Deuterium – Tritium Fusion Reaction
Fusion - Combining two light nuclei to
form a heavier, more stable nucleus.
12. Energy and Mass
Nuclear changes occur with small but measurable
losses of mass. The lost mass is called the mass
defect, and is converted to energy according to
Einstein’s equation:
DE = Dmc2
Dm = mass defect
DE = change in energy
c = speed of light
Because c2 is so large, even small amounts of
mass are converted to enormous amount of
energy.
