Newton Lewis Research Paper

Historical Concept of Lewis acids and bases

Gilbert Newton Lewis was one of the great chemists in history. His greatest discovery may well be the theory of the covalent bond in 1916, but he made many other contributions. One was his theory of acids and bases. In 1923, he wrote:

"We are so habituated to the use of water as a solvent, and our data are so frequently limited to those obtained in aqueous solutions, that we frequently define an acid or a base as a substance whose aqueous solution gives, respectively, a higher concentration of hydrogen ion or of hydroxide ion than that furnished by pure water. This is a very one sided definition . . . ."

What Lewis wanted was a general definition of an acid and a base, one that was universal no matter

. . . Since hydrogen is a constituent of most of our electrolytic solvents, the definition of an acid or base as a substance which gives up or takes up hydrogen ion would be more general than the one we used before, but it would not be universal."

Lewis then gives his definition of an acid and a

2) NO solvent need be involved.

The Lewis theory of acids and bases is more general than the "one sided" nature of the Bronsted-Lowry theory. Keep in mind that Bronsted-Lowry, which defines an acid as a proton donor and a base as a proton acceptor, requires the presence of a solvent, specifically a protic solvent, of which water is the usual example. Since almost all chemistry is done in water, the fact that this limits the Bronsted-Lowry definition is of little practical consequence.

The Lewis definitions of acid and base do not have the constraints that the Bronsted-Lowry theory does and, as we shall see, many more reactions were seen to be acid base in nature using the Lewis definition than when using the Bronsted-Lowry