Empirical, molecular and structural formulas
A formula's subscripts represent different information in different chemical models.
Key knowledge
An empirical formula gives the simplest whole-number ratio of constituent atoms. A molecular formula gives their counts in a specified molecule; different structures may share it. A structural formula also represents connectivity. For an extended ionic solid, a formula unit expresses a stoichiometric ratio rather than claiming that the crystal consists of discrete molecules.
Conditions and scope
- Specify whether the entity is a molecule, ion or extended solid.
- A molecular formula alone does not specify bonding, stereochemistry or every isotopic composition; nonstoichiometric solids need a composition range.
Sources · 2
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Paul Flowers, Klaus Theopold, Richard Langley and William R. Robinson · OpenStax/Rice University2 sources
- Chemistry 2e (2019), §2.4 Chemical formulasPaul Flowers, Klaus Theopold, Richard Langley and William R. Robinson · OpenStax/Rice UniversityTextbook chapter
- Chemistry 2e (2019), §3.1 Formula mass and the mole conceptPaul Flowers, Klaus Theopold, Richard Langley and William R. Robinson · OpenStax/Rice UniversityTextbook chapter
Evidence and review
Inspected §2.4 molecular/structural/empirical formula definitions and §3.1 ionic formula-unit discussion. Excludes §2.4's illustration calling crystalline TiO2 a molecule; the record explicitly separates extended solids from molecules.
2026-10-10 · Independent Mathematics and Information editor (/root/core_math_information). Independent AI editorial review of this entry's statements, equations, applicability conditions and source coverage. Source checks apply to these claims within their stated limits.
Entry details
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- foundation-chem-formula-representations
- Revision
- foundations-refresh.1
- Structured reference record
- Foundational reference additions