Trivial name for example, hydrogen ("water-producing"), oxygen ("acid-producing"), nitrogen ("soda-producing"), bromine ("stink"), and argon ("no reaction") were based on Greek roots, while the names of iodine and chlorine were derived from the Greek words for their characteristic colors. Indium, rubidium, and thallium were similarly named for the colors of particular lines in their emission spectra. Iridium, which forms compounds of many different colors, takes its name from "iris", the Latin for "rainbow". The noble gases have all been named for their origin or properties. Helium comes from the Greek "helios", meaning "sun" because it was first detected as a line in 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