Naming Ions (including Polyatomic Ions)

Naming Ions (including Polyatomic Ions)

Elements or compounds with a  +  or –  charge are called ions.

The  +  or –  charge is because they gained or lost electrons.

Losing an electron makes them positive (cation). Gaining an electron makes them negative (anion).

• Ca²⁺
• Cl^-
• CO₃^2-

Practice: The key to success.

Keys for Single Element Ions (like Na⁺ , Cl^-,  Ca²⁺,  N^3-):

• To name positive ions (called cations) write the name as found on the Periodic Table and add the word 'ion'.
• For the negative ions (called anions) use the name from the Periodic Table but replace the ending with ‘ide’. Then add the word 'ion' .

For Single Element Ions of Transition Metals

• Write the ionic charge (the +1, +2 ...) as a Roman Numeral surrounded by parentheses. For example, Fe³⁺ would be the Iron (III) ion.
• You'll also want to do this for Pb, Sn as well.

Keys for for Polyatomic Ions (like NO₃^-,  PO₄^3-,  NH₄⁺):

• Either memorize the formulas or look them up on a Common Ion Table.