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When writing names for ionic compounds, we must first determine if the metal in the compound is a transition metal. If the metal IS a transition metal, the charge of the metal must be shown as part of the name. On the periodic table shown below, any element shaded in blue is an element that must include a charge as part of its name.
- Even though the metals under the staircase are not usually classified as transition metals, they form ions of >1 charge, so the rules for naming them are the same as for naming transition metals.
Some metals that are in the blue region, like zinc, do only form one charge. Therefore, you may not always see their charge written as part of their name. We won’t worry about those exceptions for right now.
IF NO TRANSITION METAL IS PRESENT:
Simply write the name of each ion/ polyatomic ion present. The name ends in
- ide of no polyatomic ion is present.
Ex. CaS = calcium sulfide NaNO 3 = sodium nitrate
IF A TRANSITION METAL IS PRESENT:
The charge on the transition metal must be included in the name. This is done by writing the charge in Roman numerals in parenthesis next to the metal.
To figure out what the charge is, simply “uncross” the number from the opposite ion (do the opposite of what you would do to write the formula)
NEVER take a subscript away from a polyatomic ion!
Ex. CuCl 2 = copper (II) chloride Ex. Fe 2 (SO 4 ) 3 = iron (III) sulfate
You MUST remember to take the subscript from the ion NEXT to the metal, NOT the subscript next to the metal itself. Ex: Fe 3 O 2 = iron (II) oxide NOT iron (III) oxide
