Overall Charge Calculations

[Rachel Lipman]

How do you determine which numbers to add/subtract when calculating the overall charge in relation to the Lewis Structure?

[elizabethrojas1G]

First, you're going to find how many valence electrons the element has (refer to the periodic table).
Then, on the Lewis structure of the compound, you're going to see bonds like this - and bonds that are black circles. the black circles are your "lone pair" electrons, your L value. the shared electrons are those with the "-" because they are being shared with another element. Lastly, plug in your values to the equation Formal Charge = V-(L + s/2)