Lewis Structures for Polyatomic Ions

To draw Lewis Structures for polyatomic ions we’ll follow a few simple steps. We first count the number of valence electrons for the polyatomic ion.
Using the Periodic Table we find the number of valence electrons for each element. If the ion has a negative charge (like CN-), we add an additional electron. If it has a positive charge (like NH4 +) we subtract an electron.
We then follow the general process for drawing Lewis Structures (tps:// • How to Draw Lewis Stru... ).
Not that for polyatomic ions we place brackets around the final Lewis Structure and place the charge on the ion outside of the brackets.
For more complicate Lewis Structures it is also a good idea to check the formal charges ( • Formal Charges: Calcul... ).
Helpful Videos:
How to Draw Lewis Structures: • How to Draw Lewis Stru...
Lewis Structures Practice Video Worksheet: • Lewis Dot Structure Pr...
Determining Formal Charge: • Formal Charges: Calcul...
Formal Charge Practice Video: • Formal Charge Practice...
Finding Valence Electrons (element): • Finding the Number of ...
Finding Valence Electrons (molecule): • Finding the Number of ...
The Octet Rule: • The Octet Rule: Help, ...
Exceptions to the Octet Rule: • Exceptions to the Octe...
Finally the Lewis Structure for SO4 2- is • How to Draw the Lewis ... .