As we have mentioned before each radioactive isotope has its own decay pattern.
Not only does it decay by giving off energy and matter, but it also decays at a rate that is characteristic to itself.
The atoms that are involved in radioactive decay are called isotopes.
In reality, every atom is an isotope of one element or another.
However, we generally refer to isotopes of a particular element (e.g., Rubidium-87 (Pb)).
The number associated with an isotope is its atomic mass (i.e., protons plus neutrons).
Statistical probablity is the only thing we can know exactly.
Often students get bogged down in the fact that they don't "understand" how and why radioactive elements decay and miss the whole point of this exercise.
Scientists can use the half-life of Carbon-14 to determine the approximate age of organic objects less than 40,000 years old.
By determining how much of the carbon-14 has transmutated, scientist can calculate and estimate the age of a substance. Isotopes with longer half-lives such as Uranium-238 can be used to date even older objects.
If they can begin to comprehend that it is random and spontaneous, they end up feeling less nervous about the whole thing.