Hydrideionen

Hydrideionen is the chemical species with the formula H-. It is an anion where a hydrogen atom has gained an electron, giving it a negative charge. This makes it a hydride, specifically a hydride ion. In contrast, a neutral hydrogen atom has one proton and one electron. A hydrogen molecule (H2) consists of two hydrogen atoms bonded together.

The hydride ion is a powerful reducing agent. Its small size and high charge density make it highly reactive. It is typically found in ionic hydrides, such as sodium hydride (NaH) and calcium hydride (CaH2). In these compounds, the hydride ion is bonded electrostatically to a metal cation. These ionic hydrides react vigorously with water to produce hydrogen gas and a metal hydroxide.

Hydride ions are also important in organic chemistry, where they are transferred by reagents like lithium aluminum hydride (LiAlH4) and sodium borohydride (NaBH4). These reagents are commonly used to reduce various functional groups, such as aldehydes, ketones, and carboxylic acids, to alcohols. The hydride ion is the species that delivers the electron and proton to the substrate during these reactions. It is an essential concept in understanding reduction reactions in both inorganic and organic chemistry.