LO16 notes: VSEPR shape and polarity

TERMINOLOGY: VSEPR, electron regions, polarity, molecular geometry, bond polarity, and electronegativity

• Lewis Strucure

What is missing from a lewis structure?

Its shape! 

• VSEPR (Valence Shell Electron Pair Repulsion) 

VSEPR helps us find the shape of molecules from the lewis structure 

Each electron groups around a central atom repels one another, this repulsion defines the geometry of the molecule

This results is 5 electrom group arrangements of minimum energy seen in a large majority of molecules and polyatomic ions 

Electron center geometry is NOT (always) the same as molecular shape 

To determine the shape of a molecule consider only atoms not the lone pairs 

• Electron center vs molecular geometry (shape) 

Electron center geometry: lone pairs are considered (which are the 2 dots in the picture), and bonded pairs that are part of a bond