Deuterium, << doo TIHR ee uhm or dyoo TIHR ee uhm, >> also called heavy hydrogen, is a stable isotope of hydrogen. Isotopes are atoms of the same element that differ in mass—that is, in the amount of matter they contain. Different isotopes of an element have the same number of protons but different numbers of neutrons in their nucleus. Deuterium is an essential part of the hydrogen bomb, and is used in research in atomic physics, biochemistry, and chemistry. About 1 part in 6,400 parts of all normal hydrogen in the ocean is deuterium.
Properties.
The mass of an atom of deuterium is about twice that of a normal hydrogen atom. The nucleus of an ordinary hydrogen atom consists of only a proton. A hydrogen atom has the atomic mass 1.0079. The nucleus of a deuterium atom, called a deuteron, consists of a proton and a neutron. Deuterium has an atomic mass of 2.01410. Deuterium atoms and ordinary hydrogen atoms have one electron. Chemically, deuterium reacts in the same way as ordinary hydrogen. But it generally reacts more slowly and less completely. Deuterium combines with oxygen to form deuterium oxide, commonly called heavy water. Deuterium oxide is used as a moderator in heavy water nuclear reactors to reduce the speed of the neutrons released in a nuclear chain reaction.
Uses.
Scientists use deuterium to study organic and biochemical reactions. In a process known as deuterium labeling, the deuterium atom serves as an isotopic tracer by acting as a substitute for one or more of the regular hydrogen atoms in a molecule. After the reaction is completed, the deuterium can be located by spectroscopic studies (see Spectroscopy. This technique gives scientists important clues as to how the reaction takes place.
Scientists use deuterons as bombarding particles in particle accelerators. One such device, a cyclotron, can accelerate deuterons to energy levels of millions or even billions of electronvolts. When these particles hit the target material, they alter the composition of its atoms and form another element or a new isotope of the original element (see Transmutation of elements).
Another isotope of hydrogen, called tritium, has an atomic mass of about 3. It contains one proton plus two neutrons, and is unstable. When a mixture of deuterium and tritium is triggered by an atomic explosion, a thermonuclear (heat-induced) chain reaction takes place. The atoms of the hydrogen isotopes fuse with one another and release energy (see Fusion; Nuclear weapon (Thermonuclear weapons)).
Discovery.
Harold C. Urey, an American chemist, discovered deuterium in 1931. Urey applied Niels Bohr’s theories of the atom to the hydrogen atom (see Bohr, Niels). He distilled liquid hydrogen and detected deuterium in the liquid remaining. Urey won the Nobel Prize in chemistry in 1934 for his discovery. Gilbert N. Lewis, an American chemist, first separated deuterium oxide from ordinary water in 1932.
