Concept radiometric dating
Radioactivity and radioactive decay are spontaneous processes.Students often struggle with this concept; therefore, it should be stressed that it is impossible to know exactly when each of the radioactive elements in a rock will decay.If we know the half-life of an isotope (and we can measure it with special equipment), we can use the number of radiogenic isotopes that have been generated in a rock since its formation to determine the age of formation.Radiometric dating is the method of obtaining a rock's age by measuring the relative abundance of radioactive and radiogenic isotopes.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.There is no going back -- the process is irreversible. When we pour our popcorn kernels into a popcorn popper, the is no way to know which will pop first.And once that first kernel pops, it will never be a kernel again..is forever changed! ) Teaching example using popcorn to teach radioactive decay "A variety of a chemical element (strictly, of one particular element) which is distinguished from the other varieties of the element by a different mass number but shares the same atomic number and chemical properties (and so occupies the same position in the periodic table)." That definition may not mean anything to them.
Plotting the results of these demonstrations results in a curve of an exponential decay function.
In order to determine the age of a geologic material, we must understand the concept of half-life. The definition is: the radioactive isotopes in a system.
The units of half-life are always time (seconds, minutes, years, etc.).
Instead, it is really the Problem solving in the geosciences was forever changed with the discovery of radioactivity.
Radioactive elements can be used to understand numerical age of geological materials on time scales as long as (and even longer than) the age of the Earth.However, oxygen atoms can have between 8 and 10 neutrons in the nucleus and therefore the isotopes of oxygen have atomic masses of 16, 17, and 18 a.m.u.(and none are radioactive! Samarium (Sm) has 7 naturally occurring isotopes (3 are radioactive).