heavy water

heavy water

n.

Any of several isotopic forms of water, especially deuterium oxide, that consists chiefly of molecules containing heavy hydrogen and is used as a moderator in certain nuclear reactors.

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heavy water

n

(Chemistry / Elements & Compounds) water that has been electrolytically decomposed to enrich it in the deuterium isotope in the form HDO or D₂O

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heavy water

Water in which deuterium, a heavy isotope of hydrogen, takes the place of hydrogen. Heavy water has physical and chemical properties that are like those of ordinary water, but heavy water is 10 percent heavier and has higher freezing and boiling points. Also called deuterium oxide. Chemical formula: D₂O. Semiheavy water is similar to heavy water, but only one of the two hydrogen atoms in each molecule is replaced with deuterium. Chemical formula: DHO.

A Closer Look The nucleus of most hydrogen atoms consists of a single proton, but in one isotope of hydrogen, called deuterium or heavy hydrogen, the nucleus also contains a neutron and thus weighs nearly twice as much as standard hydrogen. The substance called heavy water is chemically identical to ordinary water (H₂O), except that the hydrogen atoms in the molecule are the deuterium isotopes (D₂O). Heavy water makes up a small percentage (0.02%) of water naturally occurring on Earth. It is an excellent moderator for nuclear reactions, slowing down the fast neutrons produced in a nuclear fission reaction, increasing the likelihood that the neutrons will successfully collide with heavy nuclei to cause further fission. Although heavy water is chemically nearly identical with ordinary water, it is about ten percent heavier and interferes with cell mitosis if consumed in place of normal water. Ice cubes made of heavy water are denser than ordinary liquid water and will sink to the bottom of a glass of cola.

Thesaurus

Noun

1.

heavy water - water containing a substantial proportion of deuterium atoms, used in nuclear reactors deuterium oxide moderator - any substance used to slow down neutrons in nuclear reactors