Presentation on theme: "Chapter 9 Notes – Part III Mr Nelson 2010. Polarity But just because a molecule possesses polar bonds does not mean the molecule as a whole will be polar."— Presentation transcript:
Chapter 9 Notes – Part III Mr Nelson 2010
Polarity But just because a molecule possesses polar bonds does not mean the molecule as a whole will be polar.
Polarity There are two ways to tell if a molecule is nonpolar: –Symmetry – perfect symmetry = nonpolar –Dipoles moments – if the dipoles cancel out the molecule is nonpolar
Examples Draw the Lewis Dot Structure for: –HCl –CCl 4
Bonding & Lone Pairs Electron pairs that are shared are called bonding pairs Electron pairs that are not bonded or shared are called lone or unshared pairs
Steric Number The total electron pairs around the central atom is the steric number. Double or triple bonds count as one steric number (electron domain). The central atom has a steric number of four.
Determining the shape of molecules
VSEPR (not the Bond girl Vesper) VSEPR: Valence Shell Electron Pair Repulsion –Electron pairs will arrange so they are as far apart as possible. ALL HAVE NEGATIVE CHARGES –ALL e - pairs determine the shape, bonded or not, but ONLY bonded pairs determine the name of the shape.