Lecture Notes 9

If it has less electrons in the molecule then it has

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: ). 7. Use the concept of formal charge to assess the plausibility of the Lewis structure. Formal Charge Formal Charge: An atom in a molecule owns its lone pairs completely, but has an equal share in bonding electron pairs. If this results in an atom having more electrons in the molecule than as a free, neutral atom, we say that the atom has a negative formal charge in the Lewis structure. If it has less electrons in the molecule, then it has a positive formal charge. FC = number of valence electrons of free atom − number of lonepair electrons − 1 number of shared electrons 2 The sum of formal charges must equal zero for a neutral molecule and must equal the charge for ions. GChem I 9.10 Lewis structures with the lowest formal charges are most plausible. Exercise: Write the Lewis structure for CF2 Cl2 (Freon-12) A = number of available valence electrons A = 4 + 2 × 7 + 2 × 7 = 32 N = number valence electrons needed for octets N = 5 × 8 = 40 S = N − A = number of shared electrons S...
View Full Document

This document was uploaded on 03/18/2014 for the course CHEM 1303 at SMU.

Ask a homework question - tutors are online