Lewis acids and bases studied chemical bonding. In 1923, Lewis wrote "An acid substance is one which can employ an electron lone pair from another molecule in completing the stable group of one of its own atoms." The Brønsted–Lowry acid–base theory was published in the same year. The two theories are distinct but complementary. A Lewis base is also a Brønsted–Lowry base, but a Lewis acid doesn't need to be a Brønsted–Lowry acid. The classification into hard and soft acids and bases (HSAB theory) followed in 1963. The strength of Lewis acid-base interactions, as measured by the standard enthalpy of formation of an adduct
Timeline of binary prefixes Timeline of binary prefixes This article presents a timeline of binary prefixes used to name memory units, in comparison of decimal and binary prefixes for measurement of information and computer storage. Historically, computers have used two different approaches to memory addressing, binary and decimal. Early decimal computers included the ENIAC, UNIVAC 1, IBM 702, IBM 705, IBM 650, IBM 1400 series, and IBM 1620. Early binary addressed computers included Zuse Z3, Colossus, Whirlwind, AN/FSQ-7, IBM 701, IBM 704, IBM 709, IBM 7030, IBM 7090, IBM 7040, IBM System/360 and DEC PDP series. Decimal systems typically had memory configured in whole