The symbol for a specific chemical element, that can stand both for an atom or a substance.
ChemicalElement
[2,"smw-datavalue-wikipage-property-invalid-title","HasComment","The IUPAC Gold Book defines the a chemical element both as:\n- a species of atoms; all atoms with the same number of protons in the atomic nucleus\n- a pure chemical substance composed of atoms with the same number of protons in the atomic nucleus\n\nThis qualifies a chemical element as a name and not a matter obejct that can stand for an atom or a substance.@en"]