Naming Ions, cations and anions

Dr. Walt Volland revised July 12, 2013 all right reserved

 
There are two types of monoatomic ions. (Monoatomic means the ion contains a single atom.)
 
There are cations like K1+ and anions like Cl1-. There is a different process for naming each.
Naming cations:
 
Cations from the main-group metals are typically named using the element name followed by the word ion.
 
Examples:
Metal symbol Element name Ion symbol Cation name
Na sodium Na1+ sodium ion
Al aluminum Al 3+ aluminum ion
Ca calcium Ca2+ calcium ion

 

 

Cations formed by metals in other groups and the bottom of the main-group can have more than one positive charge. This complicates the naming process. The different charge types must be named differently. The new system uses a Roman numeral after the element name to indicate the charge.
.
The old system which we will not use, combines the stem for the element name and the endings -ous and -ic. The -ous ending is applied to the cation with the smaller positive charge. The -ic ending is applied to the cation with the higher positive charge. This system gets particularly messy when there are more than two possible cations. You can see why a "new" system was introduced. The trouble is that both systems are around. The old names are on labels everywhere.
.
Examples:
Metal symbol
Element name
Ion symbol

Cation name (new system)

Cation name (old system)
Fe
iron
Fe2+
iron (II) ion
ferrous ion
Fe
iron
Fe 3+
iron (III) ion
ferric ion
Sn
tin
Sn2+
tin (II) ion
stannous ion
Sn
tin
Sn4+
tin (IV) ion
stannic ion
Cu
copper
Cu1+
copper (I) ion
cuprous ion
Cu
copper
Cu2+
copper (II) ion
cupric ion

Naming anions:
 
Anions from the main-group metals are named using the stem/root of the element name followed by the ending -ide.  
Examples: Here the root or stem for the element name is underlined.

Element symbol Element name   Ion symbol

      Cl             chlorine            Cl1-

Anion name

chloride ion

Br                bromine         Br 1-

bromide ion
O                  oxygen          O2-  
oxide ion
Exercise: Complete the following table by supplying the ion names. click here for answers
Element symbol
Element name
Ion symbol
Ion name
Li
lithium
Li 1+

??????????????????

F
fluorine
F1-

??????????????????

Cr
chromium
Cr2+

??????????????????

Cr
chromium
Cr3+

??????????????????

 

Revised July 12 , 2013

all rights reserved copyright 2001-2013 Dr, Walt Volland