A chemical formula is a concise list of the elements in a compound and the ratios of these elements. To better understand what a chemical formula means, we must consider how an ionic compound is constructed from its ions.
A fallacy is an incorrect argument in logic and rhetoric. It gives a result which is not valid or lacks soundness. Fallacies are either formal fallacies or informal fallacies.
A fallacy is a mistake, and a logical fallacy is a mistake in reasoning. There are, of course, other types of mistake than mistakes in reasoning. For instance, factual mistakes are sometimes referred to as fallacies. However, The Fallacy Files is specifically concerned with logical errors, not factual ones.