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Any of a class of compounds in which hydrogen is combined with another element. There are three basic types of hydrides: saline, metallic, and covalent. Saline hydrides, such as sodium hydride (NaH) and calcium hydride (CaH), are often used as portable sources of hydrogen gas (H). Metallic hydrides, such as titanium hydride (TiH), are alloylike materials (seealloy) with some properties of metals, such as lustre and electrical conductivity. Covalent hydrides (seecovalent bond) are mostly compounds of hydrogen and nonmetallic elements; they include water, ammonia, hydrogen sulfide (HS), and methane. A fourth group of hydrides, dimeric (polymeric) hydrides, is sometimes recognized (seeborane). Dimeric hydrides give off large amounts of energy when burned and may be useful as rocket fuels.
This entry comes from Encyclopædia Britannica Concise. For the full entry on hydride, visit Britannica.com.