10 Things You Didnât Know About Chronic Fatigue Syndrome. Chronic Fatigue Syndrome (CFS) is undeniably complicated in every conceivable way. The disorder has been around for decades, but the medical community has yet to assemble a clear picture of it. The condition is characterized by extreme fatigue that canât be explained by any underlying medical condition.
A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is an atom that has excess nuclear energy, making it unstable.
The term isotopes is often used to mean nuclides, because a nuclide is usually an isotope of an element. Strictly speaking, isotopes are atoms with the same number of protons but different number of neutrons in their nuclei.