Heavy hydrogen
Deuterium
Deuterium (symbol
D
or 2
H
, also known as heavy hydrogen) is one of two stable isotopes of hydrogen. The nucleus of deuterium, called a deuteron, contains one proton and one neutron, whereas the far more common hydrogen isotope, protium, has no neutron in the nucleus. Deuterium has a natural abundance in Earth's oceans of about one atom in 6420 of hydrogen. Thus deuterium accounts for approximately 0.0156% (or on a mass basis 0.0312%) of all the naturally occurring hydrogen in the oceans, while the most common isotope (hydrogen-1 or protium) accounts for more than 99.98%. The abundance of deuterium changes slightly from one kind of natural water to another (see Vienna Standard Mean Ocean Water).
The deuterium isotope's name is formed from the Greek deuteros meaning "second", to denote the two particles composing the nucleus. Deuterium was discovered and named in 1931 by Harold Urey. When the neutron was discovered in 1932, this made the nuclear structure of deuterium obvious, and Urey won the Nobel Prize in 1934. Soon after deuterium's discovery, Urey and others produced samples of "heavy water" in which the deuterium content had been highly concentrated.
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