Alternative Method
The following is equivalent:
- Draw a circle around the atom for which the formal charge is requested (as with carbon dioxide, below)
- Count up the number of electrons in the atom's "circle." Since the circle cuts the covalent bond "in half," each covalent bond counts as one electron instead of two.
- Subtract the number of electrons in the circle from the group number of the element (the Roman numeral from the older system of group numbering, NOT the IUPAC 1-18 system) to determine the formal charge.
- The formal charges computed for the remaining atoms in this Lewis structure of carbon dioxide are shown below.
It is important to keep in mind that formal charges are just that-formal, in the sense that this system is a formalism. The formal charge system is just a method to keep track of all of the valence electrons that each atom brings with it when the molecule is formed.
Read more about this topic: Formal Charge
Famous quotes containing the words alternative and/or method:
“If English is spoken in heaven ... God undoubtedly employs Cranmer as his speechwriter. The angels of the lesser ministries probably use the language of the New English Bible and the Alternative Service Book for internal memos.”
—Charles, Prince Of Wales (b. 1948)
“Protestantism has the method of Jesus with His secret too much left out of mind; Catholicism has His secret with His method too much left out of mind; neither has His unerring balance, His intuition, His sweet reasonableness. But both have hold of a great truth, and get from it a great power.”
—Matthew Arnold (1822–1888)