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
NASA Star and Exoplanet Database NASA Star and Exoplanet Database The NASA Star and Exoplanet Database (NStED) is an on-line astronomical stellar and exoplanet catalog and data service that collates and cross-correlates astronomical data and information on exoplanets and their host stars. NStED is dedicated to collecting and serving important public data sets involved in the search for and characterization of exoplanets and their host stars. The data include stellar parameters (such as positions, magnitudes, and temperatures), exoplanet parameters (such as masses and orbital parameters) and discovery/characterization data (such as published radial velocity curves, photometric light curves, images, and spectra). The NStED collects and serves