Deuterium

Deuterium/Hydrogen-2 (symbol D or 2H, 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. It has a natural abundance in Earth's oceans of about one atom in 6,420 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.

Deuterium has around twice the mass of ¹H. That means deuterated compounds behave differently than those containing 1H. Deuterium oxide, D₂O, melts/freezes at 3.8 oC (38.4 ^oF), for instance. Drinking it probably won't kill you, but you could make yourself sick.

Deuterium is an essential, although indirect, human nutrient. Formation of deuterium is the first step in the chain of reactions which produce most of the sun's energy. It is also the rate controlling step, the step which determines how bright the sun burns - and how long it lasts. Way down deep, it is deuterium which is responsible for our being here.

Deuterium is a fragile nucleus, one not tightly bound. If a ²H nucleus encounters a ¹H nucleus they can readily fuse to make ³He. This can happen even if temperature is so low that the reaction ³He + ³He --> ⁶Be --> ⁴He + ²He(?) [or 2*¹H] cannot occur at an important rate. It takes about 13 times the mass of Jupiter to raise core temperature in a gaseous body to the ignition point of deuterium fusion. It takes about 90 jupiter masses to cause ¹H fusion to ignite. Anything massive enough to ignite protium fusion is a star. Anything that fuses deuterium, but not protium is called a brown dwarf.

See also

• Protium
• Tritium
• Isotopes of hydrogen
• Hydrogen 6