Formula, Chemical (Encyclopedia of Science)
A chemical formula is a combination of chemical symbols that represents the chemical composition of a compound. At a minimum, a formula tells which elements are present in the compound and the relative amount of each element. The chemical formula most familiar to people is probably H2O, the formula for water. This formula says that water consists of two elements, hydrogen (H) and oxygen (O). Further, it says that the ratio of the two elements is two parts hydrogen and one part oxygen. On a submicroscopic scale, the formula says that a molecule of water contains two atoms of hydrogen and one atom of oxygen.
Determining chemical formulas
A chemical formula can be determined in one of two ways: by experimentation or by prediction. For example, imagine that an entirely new compound has been discovered whose formula must be determined. That compound can be broken down in the laboratory and the elements present determined. Also, the ratio of the elements can be found. The formula obtained in this way shows the simplest possible ratio of the elements present and is known as the compound's empirical formula. The word empirical means "obtained by means of experimentation."
The empirical formula of a compound may not be its true or correct formula. Consider three different chemical compounds made of carbon and hydrogen only. The first compound...
(The entire section is 1000 words.)
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