What must an alkali contain?

An alkali must contain metal atoms and hydroxyl group(s) (OH). This definition aligns with the chemical nature of alkalis, which are typically soluble bases that can neutralize acids. In a basic sense, alkalis consist of a metal ion bound to one or more hydroxide ions. Common examples include sodium hydroxide (NaOH) and potassium hydroxide (KOH), where the metal atoms (sodium and potassium, respectively) are combined with hydroxyl groups.

The presence of both metal atoms and hydroxyl groups is significant because it determines the substance's ability to react with acids and contribute to various chemical processes, such as pH regulation in skincare or body chemistry. Understanding this fundamental aspect is crucial for anyone working in fields that involve chemical interactions, such as esthetics, where pH balance can impact product effectiveness and skin health.