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.
How to Start the Excel Formula. Excel is an outstanding application for working with mathematical formulas. One of the key aspects in understanding formulas is that they start with the = sign. This = sign needs to placed in the cell where you want the result to be displayed. So to add two numbers together, first place the = sign in the cell where you would like the result, then select the cell that contains the first number in the equation. Add a + sign. Now select the cell that contains the number you are adding. Finally, press enter. Notice how the total appears.