Dating rocks using radioactive isotopes

Thus, if we start out with 1 gram of the parent isotope, after the passage of 1 half-life there will be 0.5 gram of the parent isotope left.

After the passage of two half-lives only 0.25 gram will remain, and after 3 half lives only 0.125 will remain etc.

Over 60 further radionuclides are detectable in nature, either as daughters of these, or through natural production on Earth by cosmic radiation.

More than 2400 radionuclides have half-lives less than 60 minutes.

Libby received the Nobel Prize in Chemistry for his work in 1960.

The radiocarbon dating method is based on the fact that radiocarbon is constantly being created in the atmosphere by the interaction of cosmic rays with atmospheric nitrogen.

This excess energy can be either emitted from the nucleus as gamma radiation, or create and emit from the nucleus a new particle (alpha particle or beta particle), or transfer this excess energy to one of its electrons, causing that electron to be ejected as a conversion electron.There are about 730 radionuclides with half-lives longer than 60 minutes (see list of nuclides).With the longest half lives are the 32 primordial radionuclides that have survived from the creation of the Solar System.Students should be able to understand the principles and have that as a background so that age determinations by paleontologists and geologists don't seem like black magic. Geologists in the late 18th and early 19th century studied rock layers and the fossils in them to determine relative age.William Smith was one of the most important scientists from this time who helped to develop knowledge of the succession of different fossils by studying their distribution through the sequence of sedimentary rocks in southern England.

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