Lewis - Acids And Basis Essay

614 Words3 Pages
Lewis - Acids and Bases There are several methods of defining acids and bases. While these definitions don't contradict each other, they do vary in how inclusive they are. Antoine Lavoisier, Humphry Davy, and Justus Liebig also made observations regarding acids and bases, but didn't formalize definitions. The definition that we use often in chemistry is that a base is a chemical species that donates electrons or hydroxide ions (OH-) or that accepts protons while an acid is a substance that gives up hydrogen ions (H+) when dissolved in water. This definition limits acids and bases to substances that can dissolve in water. Later on, Brønsted and Lowry defined an acid to be a proton donor and a base to be a proton acceptor. In this definition, even substances that are insoluble in water can be acids and bases. Whether or not an aqueous solution is neutral, acidic or basic depends on the hydrogen-ion concentration. We give the acidity of an aqueous solution in terms of the pH. pH is defined as the negative logarithm of the molar hydrogen-ion concentration. A pH of 7 means that a solution is neutral. A pH of below 7 means that a solution is acidic; a pH of above 7 means that a solution is basic. Gilbert Newton Lewis postulated the electron pair relationship of acids and bases that is known as the Lewis theory of acids and bases. He was probably the greatest and most influential of American chemists. Through the nineteenth century, Europe dominated science, but the first half of the twentieth century brought a tidal wave of scientific research that thrust America to the forefront. Lewis influenced this revolution by both his teaching and his research. He suggested another way of looking at the reaction between H+ and OH- ions. In the Brønsted model, the OH- ion is the active species in this reaction (it accepts an H+ ion to form a covalent bond).

More about Lewis - Acids And Basis Essay

Open Document