way in the past. Why is it important to assume that the rate of radioactive decay has
remained constant over time?Further Reading / Supplemental Links
- http://www.pbs.org/wgbh/nova/elnino/reach/living.html
- http://nvl.nist.gov/pub/nistpubs/jres/109/2/j92cur.pdf
- http://pubs.usgs.gov/gip/geotime/radiometric.html
Vocabulary
absolute age The age of an object in years.
alpha particle Particle consisting of two protons and two neutrons that is ejected from
the nucleus during radioactive decay.
beta particle Particleconsistingofasingleelectronthatisejectedfromthenucleusduring
radioactive decay. A beta particle is created when a neutron decays to form a proton
and the emitted electron.
daughter product Stable substance that is produced by the decay of a radioactive sub-
stance. For example, uranium-238 decays to produce lead-207.
half-life Amount of time required for half of the atoms of a radioactive substance to decay
and form daughter products.
ice core Cylinder of ice extracted from a glacier or ice sheet.
isotope An atom of an element that has a differing number of neutrons.
radioactive Substance that is unstable and likely to emit energetic particles and radiation.
radioactivity Emissionofhigh-energyparticlesand/orradiationbycertainunstableatoms.
radiometric dating Process of using the concentrations of radioactive substances and
daughter products to estimate the age of a material. As substances age, the amounts
of radioactive atoms decrease while the amounts of daughter materials increase.
relative age Age of an object as compared to other objects.