hydrideiona

A hydride ion is a diatomic molecule consisting of one hydrogen atom and one electron. It is a negatively charged ion, represented by the chemical formula H-. The hydrogen atom in a hydride ion has gained an extra electron, giving it a total of two electrons in its valence shell. This configuration makes the hydride ion isoelectronic with the noble gas helium. Hydride ions are not typically found in isolation in nature. They are highly reactive species and are generally formed in chemical reactions where a hydrogen atom accepts an electron.

Hydrides are compounds that contain hydrogen, and some of these compounds can be classified as ionic hydrides. In ionic hydrides, the hydrogen atom exists as a hydride ion (H-) bonded to a metal cation. These are usually formed with electropositive metals from Group 1 and Group 2 of the periodic table. For example, sodium hydride (NaH) consists of Na+ and H- ions. When these ionic hydrides react with water, they produce hydrogen gas.

In contrast, covalent hydrides involve hydrogen atoms bonded to other atoms through covalent bonds, where the hydrogen atom may not necessarily carry a significant negative charge. The concept of a hydride ion is central to understanding the chemistry of these different types of hydride compounds.