Isotopes frequently used in radiometric dating worksheet

16 Jul

A radioactive isotope decays at a constant rate proportional to the number of radioactive atoms remaining.A simple way of describing the speed of decay is to see the time it takes for half of the atoms of a radioactive parent to decay and form the daughter element(s). Various events (especially melting of the rock) will cause the isotopes in a rock to redistribute.An instrument that separates and electronically measures a spectra of atomic masses is called a mass spectrometer.There are many types of mass spectrometers, but the most frequently used in earth-science age determinations are magnetic sector mass spectrometers.In many cases the recovered amount is no larger than a spot on the sample filament and could pass through the eye of a needle.Most people today think that geologists have proven the earth and its rocks to be billions of years old by their use of the radioactive dating methods. Given so much time, the ‘impossible’ becomes possible, the possible probable, and the probable virtually certain.The decay of the parent uranium isotopes to daughter lead isotopes in samples of the Earth, Moon, and meteorites indicates that all the planets in our solar system formed 4.5 billion years ago.

isotopes frequently used in radiometric dating worksheet-3

Magnetic sector mass spectrometers consist of at least three components as illustrated in this figure.This type of mass spectrometer scheme most commonly used in geologic dating shows how ions with a specific mass are directed into the collector for counting, while others, like a race car taking the curves at the wrong speed, are lost.[18k] A difficult chemical procedure is used to concentrate the element of interest so that isotopes can be measured on a mass spectrometer.Naturally occuring radioactive isotopes (called the parent isotope) disintegrate at specific rates to make other isotopes (called daughter isotopes).The amount of time it takes for half the quantity of the original isotope to decay is constant, no matter how much is present at the beginning.