Chemistry: How to write chemical formulas

The composition of a compound is best represented by a chemical formula. It is made up of symbols and subscripts. The symbols denote the atoms that compose the compound while the subscripts indicate the number of atoms for each element present in the compound. The presence of parenthesis in a chemical formula signifies that the number of all atoms within the parenthesis should be multiplied by the number appearing outside of the parenthesis. READ details at http://www.helium.com/items/1341647