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You have selected a combination of two ions, of which at least one is polyatomic. The formula overall is not charged, but the internal pieces are, and the name of the compound is based on those component ions.

The charge of each ion is not seen directly. It is hidden in the formula but is reflected in the grouping of the bonded parts. For example the charge of S in the formula (NH4)2S is -2 which is not shown but is reflected in the number of ammonium NH4 ions bonded to S, which is 2. See the (NH4)2S example at the bottom of this page.

Naming Inorganic Compounds:  Try a new formula

Click here to see the Legend. See also: typical oxidation numbers

The positive ion must appear first (on the left).

 


name		 place a  space in between

name

 

This naming scheme does not require any Greek Numerals on multiple instances of the same atom.

 

Comments:

The number of repetitions of identical-s does not play a role in the naming.
Do not use Greek numerals. For example, The 2 in (NH4)2 in the example below is not noted in the name.
When composing the polyatomic name, don't use the word ion. For ex. NH4 = ammonium is used rather than "ammonium ion" in the naming of the formula.

If one of the -s is complex, the other one can either be complex, or a simple ion, like Cl- in NH4Cl for example.

 

Examples:

    We see these as two distinct ions but we do not use the word "ion" in the naming scheme.    
Formula on the left on the right Overall name
NH4Cl NH4 + = ammonium Cl- = chloride ammonium chloride
(NH4)2S  NH4 + = ammonium  S2- = sulfide ammonium sulfide
(NH4)2CrO4    NH4 + = ammonium   CrO4 = chromate ammonium chromate  
Cl2   Exception: we do not use the word ion in the naming, we take the name of the element from the periodic table as is. chlorine

Convention:
The name is the elemental name: chlorine because Cl2 it is a neutral diatomic molecule.
More examples of two atoms of the same elements in the molecule are:

hydrogen (H2),
nitrogen (N2),
oxygen (O2),
fluorine (F2),
bromine (Br2),
iodine (I2).

 

 

If instead of the formula can be represented as one of the following combinations, then navigate to those templates instead. Click over the relevant bubble.




 

Not all polyatomic ion names follow distinct rules. Some names are irregular and you simply have to memorize them:
see examples 1, and
examples 2, and
examples 3.

 

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