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.
Before Microsoft's Excel came about, a Harvard MBA student and his former MIT classmate built the first spreadsheet software for the Apple II. It was 1979 and Dan Bricklin and Bob Frankston wanted to see their calculators come to life. They wanted to be able to change numbers in their calculations and update their final answers. By creating VisiCalc, the first electronic spreadsheet, that's exactly what they did. Bricklin and Frankston would work at night because computer time was cheaper at night.