Sunday, June 20, 2010

Nuclear Processes

Nuclear processes are those in which an atomic nucleus changes, including radioactive
decay of naturally occurring and human-made isotopes, nuclear fission, and
nuclear fusion. As a basis for understanding this concept:
a. Students know protons and neutrons in the nucleus are held together by nuclear
forces that overcome the electromagnetic repulsion between the protons.
b. 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 EÊ=Ê mc2) is small but significant in nuclear reactions.
c. Students know some naturally occurring isotopes of elements are radioactive, as
are isotopes formed in nuclear reactions.
d. 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.
e. Students know alpha, beta, and gamma radiation produce different amounts and
kinds of damage in matter and have different penetrations.
f.* Students know how to calculate the amount of a radioactive substance remaining
after an integral number of half lives have passed.
g.* Students know protons and neutrons have substructures and consist of particles
called quarks.

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