Summary of Naming Rules

Naming Ionic Compounds

Rule number #1: Make sure you actually have an ioniccompound or not!

Example: CrO consists of chromium and Oxygen

An Ionic Compound must have a METAL(except in the case of ammonium NH4

+1)and a NON-METAL

metal non-metal

Rule number #2: Write out the correct names for the parts of the ionic compound

Example:

CrO

Cr is NOT Chlorine or Carbon or Cryptonite! It is chromium!

chromium and oxygen

Rule number #3:Put an –ide on the ending of the non-metal if it is just an monatomic anion such as Cl or Br or F.

Example: Chromium OxideCrO

Rule number #4: Figure out if you need a Roman numeral in the name.

CrOCr definitely can have more than one charge:Cr+2 or Cr+3

so a roman numeral is needed

Cr+2 or Cr+3

Rule number #3: Figure out what the Roman numeral should be.

Cr O-2 chromium oxide

Oxygen ALWAYS has a charge of -2

Therefore the Cr has to be +2 the formula is:Chromium (II) Oxide

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