The decay rate and therefore the half-life are fixed characteristics of a nuclide. Thats the first axiom of radiometric dating techniques: the half-life of a given nuclide is a constant.
Thus, an atom of carbon-14 (C14), atomic number 6, emits a beta particle and becomes an atom of nitrogen-14 (N14), atomic number 7.
A third, very rare type of radioactive decay is called electron absorption.
The rules are the same in all cases; the assumptions are different for each method.
To explain those rules, I'll need to talk about some basic atomic physics. Hydrogen-1's nucleus consists of only a single proton.
Radiometric dating methods are the strongest direct evidence that geologists have for the age of the Earth.
All these methods point to Earth being very, very old -- several billions of years old.
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.
The new atom doesnt form the same kinds of chemical bonds that the old one did. It may not even be able to hold the parent atoms place in the compound it finds itself in, which results in an immediate breaking of the chemical bonds that hold the atom to the others in the mineral. In the next part of this article, Ill examine several different radiometric dating techniques, and show how the axioms I cited above translate into useful age measurements. C14 is also formed continuously from N14 (nitrogen-14) in the upper reaches of the atmosphere.