Post on 01-Jan-2016
Molecular Geometry
bond length, angle determined experimentallyLewis structures bonding
geometryVSEPR
Valence Shell Electron Pair Repulsion
octahedron 90o bond angles
trigonal bipyramid equatorial 120o
axial 180o
big groupssmall groups
linear 180o
BeCl2
valence e- = 2 + (2 x 7) = 16e-
Cl....
..BeCl....
..
fewer than 8e-
valence pairs on Be bonding e-
linear molecule
two
linear 180o
CO2
valence e- = 4 + (2 x 6) = 16e-
CO....
.. O....
.. CO..
O..
.. ..
valence pairs on C ignore double bondstwo
single and double bonds same
linearmolecular shapemolecular geometry linear
trigonal planar 120o
SO2
valence e- = 6+ (2 x 6) = 18e-
valence pairs on Sthree
one lone pairmolecular geometry
molecular shape bent
trigonal
S O....
..O....
:
SO....
.. O....
..:
SO...... O
..
..
:
two bonding pairs
< 120o
tetrahedral 109.5o
CH4
valence e- = 4+(4 x 1) = 8e-
valence pairs on Cfour C HH
H
H109.5o
molecular geometry
molecular shape tetrahedral
tetrahedral
tetrahedral 109.5o
NH3
valence e- = 5+ (3 x 1) = 8e-
valence pairs on Nfour N HH
H
:
< 109.5o
molecular geometry
molecular shape trigonal pyramid
tetrahedral
one lone pairthree bonding pairs
tetrahedral 109.5o
H2O
valence e- = 6+ (2 x 1) = 8e-
valence pairs on OfourO HH
::
< 109.5o
molecular geometry
molecular shape bent
tetrahedral
two lone pairtwo bonding pairs
bipyramidal 120o and 1800
PCl5
valence e- = 5+ (5 x 7) = 40e-
valence pairs on Pfive
molecular geometry
molecular shape bipyramidal
bipyramidal
P
Cl....
..
Cl....
..
Cl....
..Cl....
..
Cl
......
90o
120o
180o
bipyramidal 120o and 1800
SF4
valence e- = 6+ (4 x 7) = 34e-
valence pairs on Sfive
molecular geometry
molecular shape seesaw
bipyramidal
one lone pair
four bonding pairs S..F..
..
..F..
..
..F..
....F..
..
:
< 180o
bipyramidal 120o and 1800
ClF3
valence e- = 7+ (3 x 7) = 28e-
valence pairs on Clfive
molecular geometry
molecular shape T
bipyramidal
two lone pair
three bonding pairsCl
..F..
..
..F..
..
..F..
..
::
180o90o
bipyramidal 120o and 1800
ICl2-
valence e- = 7+ (2 x 7) + e-
valence pairs on Ifive
molecular geometry
molecular shape linear
bipyramidal
three lone pair on I
two bonding pairs
= 22e-
I..Cl..
..
::
..Cl..
..
:
octahedral 90o
BrF5
valence e- = 7+ (5 x 7)
valence pairs on Brsix
molecular geometry
molecular shape square pyramidal
octahedral
= 42e-
one lone pair
five bonding pairs
BrF....
..F....
..
F....
..
F....
..
F.... ..:
octahedral 90o
XeF4
valence e- = 8+ (4 x 7)
valence pairs on Xesix
molecular geometry
molecular shape square planar
octahedral
= 36e-
two lone pair
four bonding pairsXe
F....
..F....
..
F....
..
F....
..
:
:
Cl....
..BeCl....
..
SO....
.. O....
.. S O
....
..O.... SO
...... O
..
..
S
O O
:
CO....
.. O....
.. CO..
O..
.. ..
B
: :
F
:
: : F
:
::
F: ::
C HH
H
H
N HH
H
:
O HH
::
P
Cl....
..
Cl....
..
Cl....
..
Cl....
..
Cl
......
S..F..
..
..F..
..
..F..
..
..F..
..
:
Cl..F..
....F..
....F..
..
::
I..Cl..
..
::
..Cl..
..
:
F..
.. ..S
F....
..
F....
..
F....
..F....
..
F.... ..