Lewis Acid-Base Concept. The Lewis theory classifies a substance as an acid if it acts as an electron-pair acceptor and as a base if it acts as an electron-pair donor. Other ways of classifying substances as acids or bases are the Arrhenius concept and the Bronsted-Lowry concept.ewis Acid-Base Concept. The Lewis theory classifies a substance as an acid if it acts as an electron-pair acceptor and as a base if it acts as an electron-pair donor. Other ways of classifying substances as acids or bases are the Arrhenius concept and the Bronsted-Lowry concept.
Microsoft Excel was created by Microsoft Corporation. It was first released in 1985.
The first commercially available GUI, called PARC, was developed by Xerox. It was used by the Xerox 8010 Information System, which was released in 1981. After Steve Jobs saw the interface during a tour at Xerox, he had his team at Apple develop an operating system with a similar design. Apple's GUI-based OS was included with the Macintosh, which was released in 1984. Microsoft released their first GUI-based OS, Windows 1.0, in 1985.