Stock nomenclature for inorganic compound

Inorganic compound

Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...

s is a widely used system of chemical nomenclature developed by the German chemist Alfred Stock

Alfred Stock

Alfred Stock was a German inorganic chemist. He did pioneering research on the hydrides of boron and silicon, coordination chemistry, mercury, and mercury poisoning...

 and first published in 1919. In the 'Stock system', the oxidation state

Oxidation state

In chemistry, the oxidation state is an indicator of the degree of oxidation of an atom in a chemical compound. The formal oxidation state is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic. Oxidation states are typically represented by...

s of some or all the elements in a compound are indicated in parentheses by Roman numerals.

Style

Contrary to the usual English style for parentheses, there is no space between the end of the element name and the opening parenthesis: for AgF

Silver(I) fluoride

Silver fluoride , also known as argentous fluoride and silver monofluoride, is a compound of silver and fluorine. It is a ginger-coloured solid, melting point 435 °C, which blackens on exposure to moist air. Unlike other silver halides such as silver chloride it is soluble in water to the extent...

, the correct style is "silver(I) fluoride" not "silver (I) fluoride".

Where there is no ambiguity about the oxidation state of an element in a compound, it is not necessary to indicate it with Roman numerals: hence for NaCl

Sodium chloride

Sodium chloride, also known as salt, common salt, table salt or halite, is an inorganic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms...

, sodium chloride will suffice; sodium(I) chloride(−I) is unnecessarily long and such usage is very rare.

Examples

• FeCl₂
  Iron(II) chloride
  Iron chloride, also known as ferrous chloride, is the chemical compound of formula FeCl2. It is a paramagnetic solid with a high melting point, and is usually obtained as an off-white solid. FeCl2 crystallizes from water as the greenish tetrahydrate, which is the form that is most commonly...
  
  : iron(II) chloride
• FeCl₃
  Iron(III) chloride
  Iron chloride, also called ferric chloride, is an industrial scale commodity chemical compound, with the formula FeCl3. The colour of iron chloride crystals depends on the viewing angle: by reflected light the crystals appear dark green, but by transmitted light they appear purple-red...
  
  : iron(III) chloride
• K[MnO₄
  Potassium permanganate
  Potassium permanganate is an inorganic chemical compound with the formula KMnO4. It is a salt consisting of K+ and MnO4− ions. Formerly known as permanganate of potash or Condy's crystals, it is a strong oxidizing agent. It dissolves in water to give intensely purple solutions, the...
  
  ]: potassium manganate(VII) (rarely used except in pre-university education
  Secondary education
  Secondary education is the stage of education following primary education. Secondary education includes the final stage of compulsory education and in many countries it is entirely compulsory. The next stage of education is usually college or university...
  
  , potassium permanganate
  Permanganate
  A permanganate is the general name for a chemical compound containing the manganate ion, . Because manganese is in the +7 oxidation state, the permanganate ion is a strong oxidizing agent. The ion has tetrahedral geometry...
  
   is ubiquitous)
• [Co(NH₃)₆]³⁺: hexaamminecobalt(III)

Mixed-valence compounds

• Co₃O₄
  Cobalt(II,III) oxide
  Cobalt oxide is inorganic compound with the formula Co3O4. It is one of two well characterized cobalt oxides. It is a black antiferromagnetic solid...
  
  : cobalt(II,III) oxide. Co₃O₄ is a mixed-valence compound that is more accurately described as Co^IICo^III₂O₄, i.e. [Co²⁺][Co³⁺]₂[O²⁻]₄.
• Sb₂O₄
  Antimony tetroxide
  Antimony tetroxide is an inorganic compound with the formula Sb2O4. This material, which exists as the mineral cervantite, is white but reversibly yellows upon heating...
  
  : antimony(III,V) oxide. Sb₂O₄ is better formulated as Sb^IIISb^VO₄, i.e. [Sb³⁺][Sb⁵⁺][O²⁻]₄.