has part electron chemical entity atom A chemical entity constituting the smallest component of an element having the chemical properties of the element. CHEBI:22671 CHEBI:23907 CHEBI:33250 atom atome atomo atoms atomus chebi_ontology element elements A chemical element is a species of atom having the same number of protons in their atomic nuclei (that is, the same atomic number, or Z). For example, the atomic number of oxygen is 8, so the element oxygen describes all atoms which have 8 protons. At the level of ontology, the chemical element is equivalent to the atom at the class level. - Oliver He, Kaiyong Liu. Ref: https://en.wikipedia.org/wiki/Chemical_element chemical entity atomic nucleus