Differences in mass or radioactivity can be used to see where specific elements react with other compounds.This is essential to understanding things like cellular transport, enzyme activity, protein structures, and disease mechanisms.For inorganic materials, such as rocks containing the radioactive isotope rubidium, the amount of the isotope in the object is compared to the amount of the isotope's decay products (in this case strontium).
The isotopes of an element have the same chemical properties but different weights.
This means it is difficult to separate isotopes from each other by chemical processes.
(Hydrogen is the only exception as most hydrogen atoms contain no neutrons.) The protons and neutrons are found in the atomic nucleus, while the electrons are found in the space around the nucleus and constantly orbit around it.
The sum of the protons and neutrons is the mass number.
As soon as a living organism dies, it stops taking in new carbon.
The ratio of carbon-12 to carbon-14 at the moment of death is the same as every other living thing, but the carbon-14 decays and is not replaced.For organic materials, the comparison is between the current ratio of a radioactive isotope to a stable isotope of the same element and the known ratio of the two isotopes in living organisms.Radiocarbon dating is one such type of radiometric dating.Isotopes are two forms of an element that have the same atomic number but different masses.This is due to the element having a fixed number of protons but with varying numbers of neutrons.Other useful radioisotopes for radioactive dating include Uranium -235 (half-life = 704 million years), Uranium -238 (half-life = 4.5 billion years), Thorium-232 (half-life = 14 billion years) and Rubidium-87 (half-life = 49 billion years).