Download Naming Ionic Compounds Many Ionic compounds contain

Naming Ionic Compounds
Many Ionic compounds contain polyatomic ions: ions made up of more than one atom.
 Polyatomic ions exist as a unit, so never change the subscript
o If you have to balance an ionic compound with a polyatomic ion then ( )and a subscript
must be written
 Ex. Ca (+2) and PO4 (-3) →Ca3(PO4)2 and named Calcium phosphate
o Most polyatomic ions are oxyanions
 Oxyanion is a polyatomic ion composed of an element, usually a nonmetal,
bonded to one or more oxygen atoms
o If a transitional metal and a polyatomic ion is involved
 Ex. Cu (+2) and NO3 (-1) →Cu(NO3)2 and named Copper (II) nitrate
 Note that transitional metals with varying oxidation numbers always
have to state which atom was used in the chemical compound whether
or not a polyatomic ion is used
Rules for naming Ionic Compounds
 Name the cation (metal) first and the anion (nonmetal) second
 Monatomic cations use element name
 Monatomic anions take their name from the root element name plus the suffix –ide
o Ex. CsBr is Cesium bromide
 Determine oxidation numbers of transitional metals compounds before naming to determine
Roman number I-IV
o Ex. Fe2O3 is Iron (III)oxide
 Some transitional metals only have one charge

Cadmium: Cd+2
 Zinc: Zn+2
 If the compound has a polyatomic ion, simply name the ion
o Ex. NH4Cl is Ammonium chloride
 If the polyatomic ion has an oxyanions
o The ion with more oxygen atoms is named using the root of the nonmetal plus the suffix
–ate
 Ex. NO3- is nitrate
 Ex. ClO3- is chlorate
 Ex. CO3-2 is carbonate
o The ion with fewer oxygen atoms is named using the root of the nonmetal plus the
suffix –ite
 Ex. NO2- is nitrite
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The oxyanions with the greatest number of oxygen atoms is named using the prefix per-,
the root of the nonmetal, and the suffix-ate
 ClO4- is perchlorate
 IO4- is periodate
 MnO4- is permanganate
The oxyanions with one less oxygen atom is named with the nonmetal and the suffix-ate
 SO4-2 is sulfate
The oxyanions with two fewer oxygen atoms is named using the root of the nonmetal
plus the suffix –ite
 Ex. ClO2 – is chlorite
The oxyanions with three fewer oxygen atoms is named using the prefix hypo-, the root
of the nonmetal, and the suffix –ite
 Ex. ClO – is hypochlorite
Polyatomic ions with 2 transitional metal atoms include a Di-prefix
 Ex. H2PO4- is Dihydrogen phosphate
 Ex. Cr2O7-2 is Dichromate
Some Hydrogen plus a polyatomic ion are named two ways
 Ex. HSO4- can be named bisulfate or Hydrogen sulfate
 Ex. HCO3- can be named bicarbonate or Hydrogen carbonate