(OH) refers to the hydroxide ion, which consists of one oxygen atom and one hydrogen atom, giving it the chemical formula OH⁻. It carries a negative charge due to the extra electron associated with the oxygen atom. Hydroxide ions are commonly found in various chemical reactions, particularly in acid-base chemistry, where they can neutralize acids. In aqueous solutions, hydroxide ions contribute to the basicity of a solution. For example, when sodium hydroxide (NaOH) dissolves in water, it releases hydroxide ions, increasing the solution's pH. Hydroxide ions play a crucial role in many biological and industrial processes, including water treatment and the production of soap.