Chemical formula

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A chemical formula is any of several kinds of notation for expressing the composition and structure of a chemical compound. Chemical formulas use element symbols for the atoms of each chemical element in a compound. There are several conventional types of chemical formula that present different levels of detail. An empirical formula is a type of chemical formula that shows the proportions of each chemical element by writing a subscripted whole number for each element symbol, such as C2H5 for butane, which indicates that butane contains carbon and hydrogen atoms in a 2:5 ratio. Different compounds can share the same empirical formula, such as CH2O for most carbohydrates. A molecular formula is a type of chemical formula that shows the number of atoms of each element contained in a molecule of a compound by writing the number as a subscript for each element symbol, such as C4H10 for butane. There are conventions for the order of the elements, such as the Hill system, to assist readability...

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