Summary of Naming Rules

Rule number #1: Make sure you actually have an ionic compound or not!
An Ionic Compound must have a METAL
(except in the case of ammonium NH
4
+1 ) and a NON-METAL
Example:
CrO consists of chromium and
Oxygen

Rule number #2: Write out the correct names for the parts of the ionic compound
Example: Cr is NOT Chlorine or Carbon or Cryptonite! It is chromium!
CrO 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.
CrO
Example: Chromium Ox ide

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