Molecular Shapes of Compounds

VSEPR Models

VSEPR

V = Valence

S = Shell

E = Electron

P = Pair

R = RepulsionUsed to predict the 3-D molecular shape

of molecules

VSEPR TraitsElectrons on central atom arrange themselves

as far apart as possible.Lone pairs on central atom repel the mostShared pairs on central atom repel the leastWe need to know:

- Lewis structure (#of bonded e- pairs & # of lone pair e- pairs)- VSEPR structure- VSEPR name- Bond angle

No VSEPR models for Ionic compounds

One more things that may helpGeneric formula to remember shapesA = central atomX = bonded pair e-

E = lone pair e-

Example – AX2E

-two bonded pair e-

-one lone pair e-

LinearAX2 2 bonded pairs; 0 lone pairsBond angle = 1800

Trigonal PlanarAX3

3 bonded pairs; 0 lone pairsBond angle = 1200

BentAX2E2 bonded pairs; 1 lone pairBond angle = <1200

TetrahedralAX4

4 bonded pairs; 0 lone pairsBond angle = 109.50

Trigonal PyramidalAX3E3 bonded pairs; 1 lone pairBond angle = <109.50

BentAX2E2

2 bonded pairs; 2 lone pairsBond angle = <109.50

Trigonal BipyramidalAX5

5 bonded pairs; 0 lone pairsBond angle = 900 & 1200

SeesawAX4E4 bonded pairs; 1 lone pairBond angle = <900 & 1200

T - shapeAX3E2

3 bonded pairs; 2 lone pairsBond angle = <900

LinearAX2E3

2 bonded pairs; 3 lone pairsBond angle = 1800

OctahedralAX6

6 bonded pairsBond angle = 900

Square PyramidalAX5E5 bonded pairs; 1 lone pairBond angle = <900

Square PlanarAX4E2

4 bonded pairs; 2 lone pairsBond angle = 900