Inorganic Nomenclature
Nomenclature of inorganic chemistryis a systematic method of naming inorganic chemical compounds (Inorganic compounds are those that lack carbon and hydrogen atoms), as recommended by the International Union of Pure and Applied Chemistry(IUPAC).
Inorganic compounds can be divided into binary compounds and those containing
Naming of Monoatomic Ions
Single atom anions are named with an -ide suffix: for example, H− is hydride ion
Single atom cations from Groups I, II, and III - which only from one stable positive ion - just have ion following their name: for example, Ca2+ is calcium ion.
Cations able to form more than one stable poisitive ion are named using Roman numerals in parentheses to state their valence. For example, Cu+ is copper(I), Cu2+ is copper(II).
Binary Ionic Compounds
A binary compound is a compound that consists of a combination of two elements. Compounds that end in IDE indicate that they contain only two elements. The first element is usually a positively charged metal, and the second element is usually a negatively charged nonmetal. The positively charged ion is the name of the metal, while the negatively charged ion consists of the stem plus the suffix IDE.
MonovalentMetals in Ionic Compounds | Multivalent Metals in Ionic Compounds | ||
|
|
||
Li2O |
Fe2O3 | ||
metal - lithium | non-metal - oxygen change ending to 'ide' |
metal - iron | nonmetal - oxygen |
lithium oxide | iron (III) oxide |
Binary Covalent Compounds
Binary molecular compounds are compounds that consist of exactly two nonmetal elements. Examples include HF, NO2, and P2O5. Naming binary molecular compounds is really quite easy. The first element is given its element name; the second is given its root (hydr, bor, carb, ox, fluor, etc.) followed by ide.
To be unambiguous (N2O, NO, NO2, and N2O4 all exist), we use Greek prefixes to explicitly indicate how many of each element are present.
1 | mono | 6 | hexa |
2 | di | 7 | hepta |
3 | tri | 8 | octa |
4 | tetra | 9 | nona |
5 | penta | 10 | deca |
Beyond that, it's simply a matter of remembering the following four rules to make the names a little more readable:
Rule 1: Drop mono for the first element
Rule 2: Drop all prefixes if the first element is H
Rule 3: Drop the second o in mono prior to a vowel
Rule 4: Drop the a in prefixes ending in a prior to a vowel
Examples include:
N2S | dinitrogen monosulfide |
N2O3 | dinitrogen trioxide |
CO2 | carbon dioxide |
CO | carbon monoxide |
N2O4 | dinitrogen tetroxide |
Polyatomic Ions
Polyatomic ions are common ions, especially ones containing oxygen (called tertary ions or oxoanions). Their name is determined by thier oxidation state and position in the periodic table. By knowing the most common form of several oxoanions, you can determine the formula or name for the reset. The base set include:
CO32- - carbonate NO3- - nitrate PO43- - phophate SO42- - sulphate ClO3- - chlorate
Since nonmetals can exhibit more than one oxidation state, they can form more than one oxocompound. For form of a oxoanion (eg. NO2-and NO3-) the stem of the name stays the same with the root changing to reflect a change in the number of oxygen; however, with the changing number of oxygen the charge remains the same.
change | prefix / sufix | C | N | P | S | Cl |
one more oxygen | per_____________ic | ClO4- perchlorate |
||||
_______________ic | CO32- carbonate |
NO3- nitrate |
PO43- phosphate |
SO42- sulfate / sulphate |
ClO3- chlorate |
|
one less oxygen | ______________ite | CO22- |
NO2- nitrite |
PO33- phosphite |
SO32- sulphite |
ClO2- chlorite |
two less oxygen | hypo__________ite | CO2- hypocarbonite |
NO- hyponitrite |
PO23- hypophophite |
SO22- hyposulphite |
ClO- hypochlorite |
These 5 oxoanions can be used to determine the formula or name of other oxoanions. For example:
BrO2-: | bromine is in the same group as chlorine, so therefor it is patterned off of chlorine. |
CrO42- | chromine is in the group 6, however, none of the oxoanions used to determine the pattern are in group 6. |
Common Polyatomic Ions
NH4+ | ammonium | HPO42- | hydrogen phosphate |
C2H3O2- | acetate | HS- | hydrogen sulfide | <
AsO43- | arsenate | C2O42- | oxalate |
BO33- | borate | MnO4- | permaganate |
CrO42- | chromate | O22- | peroxide |
Cr2O72- | dirchromate | SiO32- | siliconate |
CN- | cyanide | S2O32- | thiosulphate |
CNO- | cyanate | ||
SCN- | thiocyanate | Hg22+ | mercury (I) |
OH- | hydrroxide |
To name the compounds with polyatomic ions:
example:
Li3PO4: lithium phosphate
NaHSO4: sodium hydrogen sulphate
NH4Cr2O7: ammonium dichromate