1. The number of protons and neutrons determine variations
in physical properties
of elements observed in isotopes. Naturally radioactive elements decay
spontaneously. X-rays can be produced when metallic anodes are bombarded
with electrons in a cathode ray tube. (Nuclear Chemistry topics
may be included
with the study of Atomic Structure.) The discovery of fundamental
particles may
be used to develop the atomic model. Radioactive decay and half-life may
be used
in kinetics to illustrate first-order rate reactions (see Rates of Reactions
module).
2. Tritium is a naturally occurring radioactive isotope
of hydrogen. It has two
neutrons and one proton in its nucleus, exists in the diatomic state, and
constitutes a very small percentage of the hydrogen content of water. Since
it has a half-life of 12.3 years, it can be used for dating rather ãyoungä
samples. For example, after a wine is bottled, it becomes a closed system;
it
can no longer exchange substances with the outside world, and its tritium
content will decay at the rate dictated by its half-life. Meanwhile, the
naturally occurring level of tritium worldwide remains relatively constant.
The tritium level of the wine can be compared to that of ordinary water
to
determine the wineâs age. For example, if a port wine is tested for tritium
content along with ordinary water, and it is found that its tritium level
is only
30.6% of that of the tritium activity of water, then one can infer that
the wine
is 21 years old.
Nuclear physicists concentrate on the study and expansion of knowledge
of
subatomic particles, their structure, and models for the nuclear atom.
Therefore, nuclear chemistry is an area with strong overlap with a general
physics course. Radioactivity, fission, fusion, and nuclear reactors are
also
important areas to the nonscientist.
Community
Field trips to: nearby nuclear power
plant; nuclear medicine center at most large hospitals.
Societal
1.
Americium (Am) is the ionizing source in smoke detectors.
2.
Nuclear medicine.
3.
Carbon-14 is used to date objects made of wood or other formerly living
material.
Examples include the Shroud of Turin, Native American artifacts, bones,
etc.
4.
The current clamor over radon gas risks in well-insulated homes built over
uranium-rich bedrock.
5.
Camping lanterns have a mantle containing some radioactive thorium.
6.
At one time, watch dials were painted with a paint containing radium in
order
to make them glow in the dark. The radium was harmful to the health of
the
factory workers÷in particular the women who hand-painted the dials,
frequently licking their small paint brushes. Now, tritium (3H)
is used, but due
to its much shorter half-life, the face may visibly dim during the life
of the watch.
7.
Some EXIT signs are illuminated by tritium rather than by electricity.
Can
you think why this is an advantage? [In a power failure, an electrically
powered EXIT sign would not remain lighted.]
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