Chemists use two main theories to define how bases behave in chemical reactions. The Arrhenius theory states that a base releases hydroxide ions when dissolved in water. The broader Brønsted-Lowry theory defines a base as any molecule that accepts a proton.
A proton in this context is simply a hydrogen ion with a positive charge. Bases can be classified as either strong or weak depending on their chemical behavior. A strong base completely ionizes in water to release all its available hydroxide ions.
Sodium hydroxide is a common strong base used in drain cleaners and soap making. A weak base only partially ionizes and establishes a dynamic chemical equilibrium in solution. Ammonia is a well-known weak base used frequently in fertilizers and household glass cleaners.
Bases feel distinctly slippery to the touch because they react with oils on human skin. They turn red litmus paper blue and taste bitter, though you must never taste lab chemicals. In biological systems, specific bases help maintain the proper pH levels in human blood.
They are also essential in water treatment plants and large-scale industrial chemical synthesis. A common student misconception is that bases are inherently less dangerous than strong acids. In reality, concentrated strong bases can cause severe, immediate chemical burns to organic tissue.