The charge of the hydroxide ion is:

The hydroxide ion carries a charge of -1, which is characteristic of this polyatomic ion. The molecular formula for hydroxide is OH⁻, where the oxygen atom is bonded to a hydrogen atom, and the negative charge indicates that this ion has gained an extra electron.

In terms of its formation, hydroxide can be derived from the dissociation of water (H₂O), which can lose a hydrogen ion (H⁺) to result in the hydroxide ion. This negative charge is important in chemical reactions, especially in acid-base chemistry, where hydroxide acts as a base by accepting protons.

Hydroxide ions play a crucial role in various biochemical processes and in maintaining pH levels in solutions. Understanding the charge of hydroxide is essential for predicting its interactions in reactions, such as neutralization reactions with acids, where hydroxide ions combine with positive hydrogen ions to form water. Therefore, recognizing that the hydroxide ion has a charge of -1 is fundamental in chemical engineering and related fields.