Isotopes: Tiny atoms tell stories eons old (GC-08)
Relative amounts or ratios of different isotopes of special chemical
elements can tell ages and much more about geologic samples, even moon
rocks. Certain elements are really chemical families whose members, or
isotopes, share identical electronic structure, number of electrons and
protons, and chemical behavior but differ in number of neutrons in the
nucleus. Different isotopes of any element have different masses, varying
in multiples of 6 X 10-26 ounces.
A mass spectrometer (seen above) is
used to distinguish isotopes and record their ratios.
In the mass
spectrometer, charged atoms are electronically "shot" down a tube under
high vacuum and through a magnetic field. This field causes the atoms to
change direction and bends lighter isotopes more than heavier ones. By
varying the magnetic field, beams of different isotopes can be focused
onto an electronic measuring device that records the relative amounts of
the isotopes. In this way, geologists can "see" back into time.
Our Hoosier State Beneath Us: