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Telling
Time with Ageless Atoms
Atoms are ageless. They are too
small to have a clock, and they never get old or wear out.
Yet, we can use radioactive atoms to tell the age of old, and
even ancient, objects.
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Image #1
Atoms are very simple—they have an inside, the
nucleus, and an outside, a cloud of electrons. Even though the nucleus
is so much smaller, it contain thousands of times more mass and
millions of times more energy than the electron cloud.
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Image #2
Nuclei contain protons, which have a positive
charge, and neutrons, which have zero charge. The number of protons
determine the element
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Image #3
This chart shows some common elements and how many
particles their most common forms contains. Humans are made of a very
different mix of atoms than is the universe.
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Image #4
Some nuclei are unstable and eventually fall
apart, "decay". They decay randomly, but the rate is predictable.
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Image #5
For much more ancient things, other elements such
as uranium are useful.
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Image #6
For much more ancient things, other elements such
as uranium are useful.
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