Molecular formula

A notation that gives the kinds and numbers of atoms in a molecule, without necessarily showing how those atoms are connected.

Chemical element: A pure substance whose atoms share the same number of protons. Each element symbol identifies which kind of atom appears in the formula.
Empirical formula: A chemical formula expressing the simplest whole-number ratio of atoms in a compound. It gives the reduced ratio, which may not preserve a molecule’s actual atom counts.
Molar mass: The mass of one mole of a specified substance, usually expressed in grams per mole. Element counts in a molecular formula determine the molecule’s molar mass.
Water: A chemical compound whose molecules contain two hydrogen atoms and one oxygen atom. Its formula H₂O directly records the atom counts of a small molecule.
Chemical symbol: A one- or two-letter abbreviation used to represent a chemical element. Symbols such as H and O are the formula’s basic written units.
Structural formula: A representation showing how atoms in a molecule are connected. Unlike a molecular formula, it conveys connectivity and can distinguish structural isomers.
Mass spectrometry: An analytical technique that measures mass-to-charge ratios of ions to identify and characterize substances. Measured molecular masses help test candidate formulas for an unknown compound.
Glucose: A monosaccharide with molecular formula C₆H₁₂O₆. Its molecular formula shows composition but not the ring and chain forms glucose can adopt.
Chemical formula: A symbolic representation of a substance’s chemical composition using element symbols and numerical notation. Molecular formulas are one kind of chemical formula.
Condensed structural formula: A compact structural notation that groups atoms in sequence without drawing every bond. It adds information about atom arrangement that a molecular formula omits.

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