A species of atoms; all atoms with the same number of protons in the atomicnucleus.
A purechemical substance composed of atoms with the same number of protons in the atomicnucleus. Sometimes this concept is called the elementary substance as distinct from the chemical element as defined under (1), but mostly the term chemical element is used for both concepts.
Citation: 'chemical element' inIUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.C01022RISBibTexEndNote