Having a basic understanding of isotopes and nuclides is vital to understanding many aspects of nuclear energy. Here we present a quick and simple review (or preview!) of science class.
Elements are your basic chemical building blocks. They include things like hydrogen, oxygen, sodium, magnesium, iron, titanium..., anything on the periodic table of the elements. Each element on the periodic table has a different number of protons in its atomic nucleus (its dense center). Each element has a few varieties with the same number of protons, but different numbers of neutrons in the nucleus. All isotopes of a particular element act chemically-identically to each other. Figure 1 shows the periodic table of the elements. Each element listed has many (between 2 and 20+) isotopes.
Figure 1. The Periodic Table of the Elements
The arrow points to Iron (Fe), which has a few isotopes shown in Figure 2.
Figure 2.The isotopes of Iron
Make sense? Great. One particularly relevant set of isotopes acting chemically similar but neutronically different are those of the element Uranium, shown below in Figure 3.
Figure 3.The isotopes of Uranium
Isotope and nuclide are closely related terms. When one speaks of isotopes, they are referring to the set of nuclides that have the same number of protons. Nuclide is a more general term, referring to a nuclear species that may or may not be isotopes of a single element. Examples:
Many people use them interchangeably, including experts in the field. Just read the MCNP manual!