Chemistry Chapter 9 Notes #3

Representing Molecules Molecular Formula –Ex. CH 4 –Ex. H 2 O Structural/ Lewis Formula Ball & Stick Model Space Filling Model

Exceptions to the Octet Expanded Octet –Ex. PCl 5 –Due to a d e- Odd # valence e- Less than 8 e- The odd # and the less than 8 tend to bond with other molecules

Molecular Shape VSEPR Model –Valence shell electron pair repulsion model –Used to determine the shape, or geometry, of a molecule –The angle formed by any 2 terminal atoms and the central atom = bond angle –Pairs of electrons repel each other –Pairs are take up more space (they are only attracted to one nuclei)

Molecular Shape Common Shapes 1. Linear –No lone pairs of electrons –Atoms are at a 180 degree angle from each other

Molecular Shape Common Shapes 2. Trigonal Planar –No lone pairs on the central atom –3 shared pairs –Central atom has 3 terminal atoms attached’ –Bond angle = 120 degrees

Molecular Shape Common Shapes 3. Tetrahedral –No lone pairs on the central atom –Central atom has 4 terminal atoms attached –4 shared pair –Bond angle = degrees

Molecular Shape Common Shapes 4. Bent –2 lone pairs –2 shared pair –Central atom has 2 terminal atoms attached –Bond angle = 105 degrees

Molecular Shape Common Shapes 5. Trigonal Pyramidal –1 lone pairs –Central atom has 3 terminal atoms attached’ –Bond angle = 107 degrees

Review Bent Trigonal Pyramidal