Video narration
Does every definition of a base point to exactly the same action-producing OH−? Think of a school indicator test: you identify a substance by what it does. An Arrhenius base increases the concentration of OH− in water. Sodium hydroxide separates into Na+ and OH−: NaOH(aq) → Na+(aq) + OH−(aq). But a base is not defined only by producing OH−. A Bronsted-Lowry base accepts a proton, H+, from another substance. In NH3 + H2O ⇌ NH4+ + OH−, ammonia accepts the proton from water. The idea broadens further. A Lewis base donates an electron pair to form a coordinate covalent bond. In NH3 + H+ → NH4+, ammonia donates its lone pair to H+. So remember: Arrhenius means increases OH− in aqueous solution; Bronsted-Lowry means accepts H+; Lewis means donates an electron pair. These are different viewpoints, not separate kinds of bases. No. A base is defined by what it does: raising OH− in water, accepting H+, or donating an electron pair.