History

• The word isotope was invented in 1913 by Margaret Todd, a physician, during conversation with Frederick Soddy. Soddy was referring to a curious phenomenon in which it appeared that several different elements were able to occupy each area on the periodic table. Soddy's initial work was taken to refer to different radioactive forms. This definition was expanded when J. J. Thomson moved a stream of ionized neon through both electrical and magnetic fields to transmit onto a photographic plate and showed two distinct streams of ions. This was the first observation of stable isotopes.
  
  

Identification

• All isotopes differ in their number of neutrons, a subatomic particle which has no electric charge. All isotopes have the same number of protons and electrons, which are electrically active subatomic molecules. As a result, most isotopes have similar chemical and electrical properties, since these properties are primarily based on the number of protons and electrons. Neutrons help stabilize the nucleus by attracting each other (and protons) via the strong nuclear force.
  
  

Types

• Hydrogen (which has an atomic mass just over 1) is the only element which has specially named isotopes that are in use today. During the early studies of radioactivity, many elements were given names for their isotopes, though these have fallen into disuse. The two naturally occurring isotopes of hydrogen are deuterium and tritium, though others have been synthesized in a laboratory.
  
  

Features

• Deuterium has one proton and one neutron in its nucleus. It accounts for approximately 0.002 percent of the hydrogen on the planet. It is found in lesser amounts in hydrogen gas and is more common in oceanic water. Tritium has two neutrons and one proton in its nucleus. It is radioactive and occurs via the passing of cosmic rays and as a result of nuclear weapons.
  
  

Function

• Isotopes of hydrogen are used for many industrial and scientific purposes. Water, when enriched with deuterium, is called heavy water. Deuterium and its derivatives are used for chemical experiments and NMR spectroscopy. In addition, heavy water is used as a coolant for nuclear generators. Tritium was used in the past as a label in chemical tests, though this is less common now. Tritium, along with deuterium, is also a key component of nuclear fusion reactions.