Forming Chemical Compounds:

Chemistry and all other sciences are based on facts developed by experimentation.  The scientific law is a condensed statement of facts that has been established through experiment.

There are three basic laws which apply to the chemical reactions. That is the Law of Definite Proportions, the Law of Conservation of Mass, and the Law of Multiple Proportions.  Those laws are defining here to help the reader in understanding the purpose compounds and elements behave as they do.