# All samples dating

The half-life of a radioactive nuclide is defined as the time it takes half of a sample of the element to decay.A mathematical formula can be used to calculate the half-life from the number of breakdowns per second in a sample of the nuclide.I found several good sources, but none that seemed both complete enough to stand alone and simple enough for a What is radiometric dating?Simply stated, radiometric dating is a way of determining the age of a sample of material using the decay rates of radio-active nuclides to provide a 'clock.' It relies on three basic rules, plus a couple of critical assumptions.The mass number doesnt change, while the atomic number goes down by 1.

The mass number doesn't change, but the atomic number goes up by 1.

Thats the essence of radiometric dating: measure the amount thats present, calculate how much is missing, and Obviously, the major question here is "how much of the nuclide was originally present in our sample? If an element has more than one nuclide present, and a mineral forms in a magma melt that includes that element, the elements different nuclides will appear in the mineral in precisely the same ratio that they occurred in the environment where and when the mineral was formed. The third and final axiom is that when an atom undergoes radioactive decay, its internal structure and also its chemical behavior change.

Losing or gaining atomic number puts the atom in a different row of the periodic table, and elements in different rows behave in different ways. C14 is radioactive, with a half-life of 5730 years.

Some nuclides have very long half-lives, measured in billions or even trillions of years.

Others have extremely short half-lives, measured in tenths or hundredths of a second.