In
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 ...
, the IUPAC nomenclature of inorganic chemistry is a
systematic
Systematic may refer to:
Science
* Short for systematic error
* Systematic fault
* Systematic bias, errors that are not determined by chance but are introduced by an inaccuracy (involving either the observation or measurement process) inheren ...
method of naming
inorganic chemical compounds, as recommended by the
International Union of Pure and Applied Chemistry (IUPAC). It is published in ''
Nomenclature of Inorganic Chemistry
In chemical nomenclature, the IUPAC nomenclature of inorganic chemistry is a systematic method of naming inorganic chemical compounds, as recommended by the International Union of Pure and Applied Chemistry (IUPAC). It is published in ''Nomenclat ...
'' (which is informally called the Red Book). Ideally, every
inorganic compound
In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...
should have a name from which an unambiguous
formula
In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwee ...
can be determined. There is also an
IUPAC nomenclature of organic chemistry.
System
The names "
caffeine" and "
3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione
Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class. It is mainly used recreationally as a cognitive enhancer, increasing alertness and attentional performance. Caffeine acts by blocking binding of adenosine ...
" both signify the same chemical compound. The systematic name encodes the structure and composition of the caffeine molecule in some detail, and provides an unambiguous reference to this compound, whereas the name "caffeine" just names it. These advantages make the systematic name far superior to the common name when absolute clarity and precision are required. However, for the sake of brevity, even professional chemists will use the non-systematic name almost all of the time, because caffeine is a well-known common chemical with a unique structure. Similarly, H
2O is most often simply called
water in English, though other chemical names
do exist.
# Single atom
anions are named with an ''-ide'' suffix: for example, H
− is
hydride.
# Compounds with a positive
ion (
cation
An ion () is an atom or molecule with a net electrical charge.
The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...
): The name of the compound is simply the cation's name (usually the same as the element's), followed by the anion. For example, NaCl is ''
sodium chloride
Sodium chloride , commonly known as salt (although sea salt also contains other chemical salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With molar masses of 22.99 and 35.45 g ...
'', and CaF
2 is ''
calcium fluoride''.
#
Cation
An ion () is an atom or molecule with a net electrical charge.
The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...
s of transition metals able to take multiple charges are labeled with
Roman numerals
Roman numerals are a numeral system that originated in ancient Rome and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages. Numbers are written with combinations of letters from the Latin alphabet, eac ...
in parentheses to indicate their
charge. For example, Cu
+ is copper(I), Cu
2+ is copper(II). An older, deprecated notation is to append ''
-ous
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