Chemical element whole number. For example, the relative atomic mass of chlorine is 35.453 u, which differs greatly from a whole number as it is an average of about 76% chlorine-35 and 24% chlorine-37. Whenever a relative atomic mass value differs by more than 1% from a whole number, it is due to this averaging effect, as significant amounts of more than one isotope are naturally present in a sample of that element. Chemists and nuclear scientists have different definitions of a "pure element". In chemistry, a pure element means a substance whose atoms all (or in practice almost all) have the
Chemical nomenclature the element name. For example, NH is called "azane". This naming method has been developed principally for coordination compounds although it can be more widely applied. An example of its application is [CoCl(NH)]Cl pentaamminechloridocobalt(III) chloride. Ligands, too, have a special naming convention. Whereas "chloride" becomes the prefix "chloro-" in substitutive naming, in a ligand it becomes "chlorido-". Chemical nomenclature A chemical nomenclature is a set of rules to generate systematic names for chemical compounds. The nomenclature used most frequently worldwide is the one created and developed by the International Union of Pure and Applied Chemistry (IUPAC). The IUPAC's rules for