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
  1. Write the metal name
  2. Write the non-metal name with its ending changed to 'ide'
  1. Determine the valence of the non-metal.
  2. Using the valence of the non-metal determine the valence of the multivalent metal. The sum of the metal and non-metal valences should be zero.
  3. Write the metal name followed by its valence writen in romal numerals in brackets.
  4. Write the non-metal name with the ending changed to 'ide'.
  Li2O
Fe2O3
metal - lithium   non-metal - oxygen
change ending to 'ide'

metal - iron
multivalent, from reverse cross
valence of 3+

nonmetal - oxygen
change ending to 'ide'

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-
carbonite

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.
chlorate has 3 oxygens, and since there are only 2 oxygen here than its sufix will be 'ite'
therefore its name will be bromite

CrO42-

chromine is in the group 6, however, none of the oxoanions used to determine the pattern are in group 6.
sulfur, in group 16, however will be the base of the pattern.
suplfate has 4 oxygen, and since there are 4 its suffix will be 'ate'
therefore its name will be chromate

 

Common Polyatomic Ions

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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:

  1. Name the non-metal.
  2. Name the polyatomic ion.
 

example:
       Li3PO4:           lithium phosphate
       NaHSO4:       sodium hydrogen sulphate
       NH4Cr2O7:    ammonium dichromate