When the number of neutrons is in balance with the number of protons which does not necessarily means that the number of neutrons has to be exactly the same as the number of protons then the atoms of a particular element is said to be stable. Radium, a grandparent of lead, decays to radon, the radioactive gas that can be found in some basements. So, you can use the radioactive elements to measure the age of rocks and minerals. It works because we know the fixed radioactive decay rates of uranium, which decays to lead, and for uranium, which decays to lead These radionuclides—possibly produced by the explosion of a supernova—are extinct today, but their decay products can be detected in very old material, such as that which constitutes meteorites.
Deep time Geological history of Earth Geological time units.
How do geologists use carbon dating to find the age of rocks?
Annual Review of Nuclear Science. Want to watch this again later? All ordinary matter is made up of combinations of chemical elementseach with its own atomic numberindicating the number of protons in the atomic nucleus. The limestone itself cannot be radiometrically dated, so can only be bracketed between the ages of the granite and the pegmatite. This page was last edited on 7 Januaryat For rocks dating back to the beginning of the solar system, this requires extremely long-lived parent isotopes, making measurement of such rocks' exact ages imprecise.