Chemical nomenclature Therefore, the name of the compound is calcium hydroxide. If one is asked to write the formula for copper(I) chromate, the Roman numeral indicates that copper ion is Cu and one can identify that the compound contains the chromate ion (). Two of the 1+ copper ions are needed to balance the charge of one 2− chromate ion, so the formula is CuCrO. Type-III binary compounds are covalently bonded. Covalent bonding occurs between nonmetal elements. Covalently-bonded compounds are also known as "molecules". In the compound, the first element is named first and with its full elemental name. The second element
Chemical element for californium and Es for einsteinium), are always capitalized (see below). In the second half of the twentieth century, physics laboratories became able to produce nuclei of chemical elements with half-lives too short for an appreciable amount of them to exist at any time. These are also named by IUPAC, which generally adopts the name chosen by the discoverer. This practice can lead to the controversial question of which research group actually discovered an element, a question that delayed the naming of elements with atomic number of 104 and higher for a considerable amount of time. (See element naming controversy).