1. Daily Science
Draw the Lewis structure for NO2-1 . How many sigma and pi bonds does it have?
Draw the Lewis structure for the following and tell how many sigma and pi bonds there are
SeO3

2. VSEPR Theory
Pg. 53

3. Molecular shape
You can determine the shape of a molecule based on the Valence Shell Electron Pair Repulsion model (VSEPR)
Electrons repel each other and determine shape
Bond angles are predicted using VSEPR

4. Steps for VSEPR model Draw Lewis Structure
Determine the total number of “things” attached to central atom
Things includes bonds and lone pairs
A lone pair counts as 1 ‘thing’
Double and triple bonds count as one thing
Use the chart to determine the molecular shape
Ex. CH4, H2O, and SO3

5. Total Electron Pairs (‘Things’)
Number of bonded electron pairs (atoms)
Number of lone pairs of electrons
Molecular Shape
Bond Angles 2
Linear
180 3
Trigonal Planar
120 1
V-shaped (bent)
104.5 4
Tetrahedral
109.5
Trigonal Pyramidal
107 5
Trigonal Bipramidal
90, 120
Seesaw
90, 120, 180
T-Shaped 90
108 6
Octahedral
Square Pyramidal
Square Planar

6. Pg. 54 CS2 CH3Cl PI5 NF3 O2 TeF2 SO32- CH2O SeF6 Formula Total v.e.
Lewis
Structure
Total bonds (‘things’) around central atom
# of bonded atoms
# lone pair
Shape name
CS2
CH3Cl
PI5
NF3 O2
TeF2
SO32-
CH2O
SeF6