1. Svante August Arrhenius taught himself to read at age three and graduated from high school as the youngest and brightest in his class. As a student at the University of Uppsala he studied how electricity passed through solutions. He proposed that the resulting electric current from an aqueous sodium chloride solution was carried not by ordinary sodium and chlorine atoms, but by atoms carrying an electric charge--sodium ions and chloride ions. These ideas, which Arrhenius presented in 1884 in his Ph.D. thesis, met with resistance. He was awarded the lowest possible passing grade by his examiners.
Fortunately, Van't Hoff and Ostwald, two influential physical chemists, were impressed and encouraged him to continue work in physical chemistry. In 1887, Arrhenius proposed that the characteristic properties of acids in water solution are the properties of hydrogen ion and those of bases, the properties of hydroxide ion. When J. J. Thompson discovered the electron in the 1890s, the idea of "ions" which Arrehenius proposed in his thesis suddenly became credible. In 1903, for the same thesis that had barely earned him a passing grade in his Ph.D. examination, Arrhenius was awarded the Nobel Prize in chemistry. In 1959 Sweden issued a postage stamp on the occasion of his birth centenary.
2. Johannes Brønsted was born in Denmark in 1879. When he was thirteen his father died; he was supposed to follow in his father's profession of civil engineer. However, he was interested in chemistry and studied it in college. In 1908, he earned his doctorate and was selected as a new professor of chemistry at the University of Copenhagen. While studying how acids and bases catalyzed reactions in 1921, he clarified what acids and bases were. Since the properties of acids and bases were opposites, Brønsted felt it made more sense to supply definitions that were opposites. In 1923 he suggested that if acids were species that gave up a proton, bases are species that accept a proton. At the same time, Thomas Lowry, a British chemist, independently proposed the same definition. This definition represented a greater flexibility that extended acid-base notions into areas in which the old view was inadequate. For examples, ions could be classified as acids or bases and acid-base reactions could occur without water being present.
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