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=== Molecular formula ===
[[File:Isobutane_numbered_2D.svg|thumb|right|180px|[[Isobutane]] structural formula<br />Molecular formula: {{chem2|C4H10}}<br />Condensed formula: {{chem2|(CH3)3CH}}]]

{{Image frame
|content=<chem>H-\overset{\displaystyle H \atop |}{\underset{| \atop \displaystyle H}{C}}-\overset{\displaystyle H \atop |}{\underset{| \atop \displaystyle H}{C}}-\overset{\displaystyle H \atop |}{\underset{| \atop \displaystyle H}{C}}-\overset{\displaystyle H \atop |}{\underset{| \atop \displaystyle H}{C}}-H</chem>
|align=right|width=180
|caption=[[n-Butane|''n''-Butane]] structural formula<br />Molecular formula: {{chem2|C4H10}}<br />Condensed formula: {{chem2|CH3CH2CH2CH3}}
}}

Molecular formulae simply indicate the numbers of each type of atom in a molecule of a molecular substance. They are the same as empirical formulae for molecules that only have one atom of a particular type, but otherwise may have larger numbers. An example of the difference is the empirical formula for glucose, which is {{chem2|CH2O}} (''ratio'' 1:2:1), while its molecular formula is {{chem2|C6H12O6}} (''number of atoms'' 6:12:6). For water, both formulae are {{chem2|H2O}}. A molecular formula provides more information about a molecule than its empirical formula, but is more difficult to establish.