Empirical formula

An empirical formula expresses the simplest whole-number ratio of the elements in a compound. It gives relative atom counts, not necessarily the number of atoms in a molecule.

Chemical element: A pure substance made of atoms with the same number of protons. Empirical formulas state the relative amounts of each element in a compound.
Percent composition: The mass percentage contributed by each element in a compound. Percentages can be treated as sample masses when deriving the ratio.
Molecular formula: A formula giving the actual number of atoms of each element in a molecule. Comparing it with an empirical formula shows whether the simplest ratio is the molecular count.
Structural formula: A representation showing how atoms are connected within a molecule. It conveys bonding arrangement, which an empirical formula does not specify.
Chemical compound: A substance made of atoms of two or more elements chemically bonded in fixed proportions. An empirical formula summarizes the elemental proportions that define a compound.
Stoichiometry: The quantitative study of relationships among reactants and products in chemical reactions. Empirical formulas provide elemental ratios used in stoichiometric calculations.
Molecular mass: The mass of a molecule, calculated from the masses of its constituent atoms. A molecular mass can determine the integer multiple linking molecular and empirical formulas.
Lewis structure: A diagram showing valence electrons and bonds among atoms in a molecule or ion. It gives electron and bonding detail absent from an empirical formula.
Mole (unit): The SI unit for amount of substance, defined as exactly 6.02214076 × 10²³ specified entities. Converting measured masses to moles makes elemental proportions comparable.
Dimensional analysis: A calculation method that tracks units to check or construct quantitative relationships. Unit conversions keep mass-to-mole steps consistent in the derivation.

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