IUPAC nomenclature of inorganic chemistry
In chemical nomenclature, the IUPAC nomenclature of inorganic chemistry is a
System
The names "
- Single atom anions are named with an -ide suffix: for example, H− is hydride.
- Compounds with a positive cation): 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, and CaF2 is calcium fluoride.
- complex (chemistry).
- Oxyanions (polyatomic anions containing oxygen) are named with -ite or -ate, for a lesser or greater quantity of oxygen, respectively. For example, NO−
2 is nitrite, while NO−
3 is nitrate. If four oxyanions are possible, the prefixes hypo- and per- are used: hypochlorite is ClO−, perchlorate is ClO−
4. - The prefix bi- is a deprecated way of indicating the presence of a single hydrogen ion, as in "sodium bicarbonate" (NaHCO3). The modern method specifically names the hydrogenatom. Thus, NaHCO3 would be pronounced sodium hydrogen carbonate.
Positively charged ions are called cations and negatively charged ions are called anions. The cation is always named first. Ions can be metals, non-metals or polyatomic ions. Therefore, the name of the metal or positive polyatomic ion is followed by the name of the non-metal or negative polyatomic ion. The positive ion retains its element name whereas for a single non-metal anion the ending is changed to -ide.
- Example: sodium chloride, potassium oxide, or calcium carbonate.
When the metal has more than one possible ionic charge or
An older system used prefixes and suffixes to indicate the oxidation number, according to the following scheme:
Oxidation state | Cations and acids | Anions |
---|---|---|
Lowest | hypo- -ous | hypo- -ite |
-ous | -ite | |
-ic | -ate | |
per- -ic | per- -ate | |
Highest | hyper- -ic | hyper- -ate |
Thus the four oxyacids of chlorine are called hypochlorous acid (HOCl),
Traditional naming
Simple ionic compounds
An ionic compound is named by its cation followed by its anion. See polyatomic ion for a list of possible ions.
For cations that take on multiple charges, the charge is written using
The
List of common ion names
Monatomic anions:
- NH+
4 ammonium - H
3O+
hydronium - NO−
3 nitrate - NO−
2 nitrite - ClO−
hypochlorite - ClO−
2 chlorite - ClO−
3 chlorate - ClO−
4 perchlorate - SO2−
3 sulfite - SO2−
4 sulfate - S
2O2–
3 thiosulfate - HSO−
3hydrogen sulfite (or bisulfite) - HCO−
3hydrogen carbonate (or bicarbonate) - CO2−
3 carbonate - PO3−
4 phosphate - HPO2−
4 hydrogen phosphate - H
2PO−
4 dihydrogen phosphate - CrO2−
4chromate - Cr
2O2−
7dichromate - BO3−
3 borate - AsO3−
4 arsenate - C
2O2−
4 oxalate - CN−
cyanide - SCN−
thiocyanate - MnO−
4 permanganate
Hydrates
Hydrates are ionic compounds that have absorbed water. They are named as the ionic compound followed by a numerical prefix and -hydrate. The numerical prefixes used are listed below (see IUPAC numerical multiplier):
For example, CuSO4·5H2O is "copper(II) sulfate pentahydrate".
Molecular compounds
Inorganic molecular compounds are named with a prefix (see list above) before each element. The more electronegative element is written last and with an -ide suffix. For example, H2O (water) can be called dihydrogen monoxide. Organic molecules do not follow this rule. In addition, the prefix mono- is not used with the first element; for example, SO2 is sulfur dioxide, not "monosulfur dioxide". Sometimes prefixes are shortened when the ending vowel of the prefix "conflicts" with a starting vowel in the compound. This makes the name easier to pronounce; for example, CO is "carbon monoxide" (as opposed to "monooxide").
Common exceptions
The "a" of the penta- prefix is not dropped before a vowel. As the IUPAC Red Book 2005 page 69 states, "The final vowels of multiplicative prefixes should not be elided (although 'monoxide', rather than 'monooxide', is an allowed exception because of general usage)."
There are a number of exceptions and special cases that violate the above rules. Sometimes the prefix is left off the initial atom: I2O5 is known as iodine pentaoxide, but it should be called diiodine pentaoxide. N2O3 is called nitrogen sesquioxide (sesqui- means 1+1⁄2).
The main oxide of phosphorus is called phosphorus pentaoxide. It should actually be diphosphorus pentaoxide, but it is assumed that there are two phosphorus atoms (P2O5), as they are needed in order to balance the oxidation numbers of the five oxygen atoms. However, people have known for years that the real form of the molecule is P4O10, not P2O5, yet it is not normally called tetraphosphorus decaoxide.
In writing formulas, ammonia is NH3 even though nitrogen is more electronegative (in line with the convention used by IUPAC as detailed in Table VI of the red book). Likewise, methane is written as CH4 even though carbon is more electronegative (
Nomenclature of Inorganic Chemistry
Nomenclature of Inorganic Chemistry, commonly referred to by chemists as the Red Book, is a collection of recommendations on IUPAC nomenclature, published at irregular intervals by the IUPAC. The last full edition was published in 2005,[2] in both paper and electronic versions.
Release year | Title | Publisher | ISBN |
---|---|---|---|
2005 | Recommendations 2005 (Red Book) | RSC Publishing | 0-85404-438-8 |
2001 | Recommendations 2000 (Red Book II) (supplement) |
RSC Publishing | 0-85404-487-6 |
1990 | Recommendations 1990 (Red Book I) | Blackwell | 0-632-02494-1 |
1971 | Definitive Rules 1970 | Butterworth | 0-408-70168-4 |
1959 | 1957 Rules | Butterworth | |
1940/1941 | 1940 Rules | Scientific journals |
See also
- IUPAC nomenclature
- IUPAC nomenclature of organic chemistry
- List of inorganic compounds
- Water of crystallization
- IUPAC nomenclature of inorganic chemistry 2005 (the Red Book)
- Nomenclature of Organic Chemistry (the Blue Book)
- Quantities, Units and Symbols in Physical Chemistry (the Green Book)
- Compendium of Chemical Terminology(the Gold Book)
- Compendium of Analytical Nomenclature (the Orange Book)
References
- ^ Nomenclature of Inorganic Chemistry IUPAC Recommendations 2005 - Full text (PDF)
2004 version with separate chapters as pdf: IUPAC Provisional Recommendations for the Nomenclature of Inorganic Chemistry (2004) Archived 2008-02-19 at the Wayback Machine