Molecular formula: definition in chemistry
Molecular formula: A formula that shows the actual number of atoms of each element in one molecule of a substance, such as C₆H₁₂O₆ for glucose.
The molecular formula is always a whole-number multiple of the empirical formula, and the multiple is found by dividing the molar mass by the mass of the empirical formula unit. It does not show how the atoms are connected, so different compounds, called isomers, can share the same molecular formula. Structural formulas or models are needed to tell isomers apart.
Examples
- Water — H₂O
- Butane — C₄H₁₀, while its empirical formula is C₂H₅
- Glucose: 180 g/mol ÷ 30 g/mol for CH₂O = 6, so C₆H₁₂O₆
- Ethanol and dimethyl ether — both C₂H₆O, but different compounds