Radioactive dating is called
There are always a few astronomy students who ask me the good question (and many others who are too shy to ask), ``what if you don't know the original amount of parent material?'' or ``what if the rock had some daughter material at the very beginning?All atoms of an element have the same number of protons in their nucleus and behave the same way in reactions.The atoms of an isotope of a given element have same number of protons AND neutrons in their nucleus.'' The age can still be determined but you have to be more clever in determining it.
Subtract the initial amount of daughter isotope A from the rock sample to get the amount of daughter isotope A that IS due to radioactive decay.However, the crater number relation must be calibrated against something with a known age.To measure the passage of long periods of time, scientists take advantage of a regularity in certain unstable atoms.The discussion above is for the case of determining when a ) are the radioactive carbon-14 isotope that will decay to form nitrogen-14 with a half-life of 5,730 years.Carbon-14 is being produced continuously in our atmosphere when cosmic rays (extremely high-energy particles from space, mostly protons) collide with air molecules.