Electron geometry and Molecular geometry
Hybrid.
sp
Steric #
#
atoms
#
lone pairs
Electron
geometry
Molecular
geometry
Molecular
geometry
(Attache
d atoms
+ lone
pairs)
(atoms
attached to
central
atom)
(attached to
central atom)
(based on
static #)
(how atoms are
attached to
central atom)
*polarity
Shape
Look only at
atoms attached
to center
2
2
0
linear
linear
180
yes
3
3
0
trigonal
planar
trigonal
planar
120
Yes
3
2
1
trigonal
planar
bent
<120
No
4
4
0
tetrahedral
tetrahedral
109.5
yes
4
3
1
tetrahedral
trigonal
pyramid
<109.5
No
4
2
2
tetrahedral
bent
<109.5
No
5
5
0
trigonal
bipyramidal
trigonal
bipyramidal
90,120,180
Yes
5
4
1
trigonal
bipyramidal
seesaw
90,120,180
No
5
3
2
trigonal
bipyramidal
T-shaped
90, 180
No
5
2
3
trigonal
bipyramidal
linear
180
yes
sp2
Symmteric?
angle
sp3
sp3d
6
6
0
octahedral
octahedral
90, 180
Yes
6
5
1
octahedral
square
pyramidal
90, 180
No
6
4
2
octahedral
square planar
90, 180
Yes
*more
than one
type of
atom on
central
atom =
polar &
nonsymme
trical
*0 lone pairs
=
symmetrical
& non-polar
sp3d2
*bold-italic are
symmetrical &
non-polar
Lewis Structure Rules
1. Attach the atoms together in a skeletal structure
Lease Electro negative element -central
halogens and hydrogen – terminal
2. Calculate the total number of valence electrons
available for bonding
3. Attach atoms with single bonds and subtract
electrons used from total
4. Add remaining electrons in pairs to complete the
octets of all the CORNER atoms working your way to
central atom (remember H only wants 2 electrons).
Keep subtracting from the total
5. If there are not enough electrons to complete the
octet of the central atom, bring pairs of electrons
from an attached atom – Make Double, Triple bonds
6. Expanded Octet Give extras to central atom
7. Follow Common Bonding patterns
some common bonding patterns
• C = 4 bonds & 0 lone pairs
•
•
•
•
•
4 bonds = 4 single, or 2 double, or single + triple,
or 2 single + double
N = 3 bonds & 1 lone pair,
O = 2 bonds & 2 lone pairs,
H and halogen = 1 bond,
Be = 2 bonds & 0 lone pairs,
B = 3 bonds & 0 lone pairs