Hybridization
Carbon 1s2 2s2 2p2
two electrons in p with a figure of
8 shape p electrons have slightly
more energy than s electrons so
therefore any bonds formed
would not be even.
What happens to the orbitals of
carbons electrons
. First the electrons are promoted
to higher energy orbitals this is
called an excited state and breaks
Hund’s rule. Make a note that an
excited state is when electrons
have enough energy to jump up
into an orbital that is further out.
Is the blending
together of
electron orbitals in
order to make new
equal ones
Let’s consider the
molecule methane
CH4. Molecules
need have equal
bonds so the four
bonds with the
hydrogen’s must be
equal but as an
atom carbon has
two of its four
electrons in an s
orbital with a
spherical shape and
When atoms bond
the orbitals that
make up their
electron
configuration also
changes.
In order for the
central atom of a
molecule to form
equal bonds with
other atoms the
different outer
orbitals must be
combined to form a
new set of equal
orbitals
Hybridizing atomic
orbitals produces
completely new
orbitals
So different hybridizations result
in different shapes
If we mix one s with one p it
results in linear molecules
If we mix one s with two p’s it
results in trigonal planar
ect
Four hybrid orbitals were
required since there are four
atoms attached to the central
carbon atom. These new orbitals
will have an energy slightly above
the 2s orbital and below the 2p
orbitals as shown in the following
illustration. Notice that no change
occurred with the 1s orbital.
Now 4 new but
equal orbitals have
been formed (
don’t be fooled by
the name sp3 This
does not mean that
the orbitals are one
s and 3 p orbitals it
means instead that
these new equal
super orbital were
made from
combining one s
with 3 p to make 4
brand new orbitals.
In the case of
methane, the three
2p orbitals of the
carbon atom are
combined with its
2s orbital to form
four new orbitals
called "sp3" hybrid
orbitals. The name
is simply a tally of
all the orbitals that
were blended
together to form
these new hybrid
orbitals.
A liger is not a tiger
and a lion it is a
liger
Sp3 means sp3 not one s and 3p
only that that was what was
mixed to create them.
The blending of
orbitals is a bit like
the blending of
colors blue and
yellow when mixed
together make
green. They are no
longer blue and
yellow they are
green. This is the
same with s and p
orbitals in
methane.
The key take away here are that
the hybridized orbitals are new
and are not 1s and 3p orbitals as
the name might imply but are in
fact 4 branded new equivalent
orbitals with different shapes
from their parent orbitals
CFU
• What are sp3 hybridized orbitals?
• Would you expect sp2 orbitals to be more
spherical or more dumb bell shaped than sp3?
• Why?
These hybrid
orbitals have 75%
p-character and
25% s-character
which gives them a
shape that is
shorter and fatter
than a p-orbital.
The new shape
looks a little like
these. Notice that
all four orbitals are
identical.
.
Sp3 are new
hybridized orbitals
made by combining
1 s with 3 p orbitals
More dumbell
shaped
because they are
33% s and 67% d
While students are
solving the cfu TW
circulate and locate
exemplar note
taking
TW will be looking
for questions in the
left had column
and annotated
diagrams
Lecture Part 2
The electron
geometry
surrounding the
central atom is
directly linked to
the number of new
orbitals that have
been formed.
So the shape and
the hybridization
are linked
The electrons of
the nitrogen in the
ammonia molecule
will be hybridized a
from being 2S2 and
2p3 to become 4
equal sp3 orbitals
Thus the hybridized orbitals must
comprise four parent orbitals.
Therefor one s and 3p orbitals
must be mixed together to create
four new orbitals
We can see that in
ammonia the
electrons are
pointing in four
different directions.
We can use this as
a 99.9% reliable
way of determining
the hybridization of
the N in ammonia.
Four different
directions means
four equal orbitals
must be created.
So using our short
cut technique we
can determine that
the electron pairs
point in four
different directions
so the oxygen in
water must be sp3
hybridized.
This is confirmed
when we study the
orbital diagram of
the oxygen in water
and we see that the
2s electrons are
blended with the
2p orbitals to
create 4 brand new
sp3 orbitals
So what when
more than four
equal orbitals are
required? The d
orbitals have to be
tapped into. This
means electron
pairs travelling in
five directions
would have a sp3d
hybridization and 6
different directions
would be sp3d2.
# of different
# of orbitals Hybridization
directions electron that are
pairs go in
combined
2
3
4
5
6
2
3
4
5
6
sp
sp2
sp3
sp3d1
sp3d2
If pairs of electrons in 5
directions then the new super
orbitals must be sp3d
If pairs of electrons in 6
directions then the new super
So to identify the
hybridization that
has taken place we
can look at the
shape of the
electron geometry
If pairs of electrons
go in 2 directions
then the new super
orbitals must be sp
If pairs of electrons
in 3 directions then
the new super
orbitals must be sp2
orbitals must be sp3d2
If pairs of electrons
in 4 directions then
the new super
orbitals must be sp3
Sp2
This means the electron densities
are aligned in three different
directions. So three new orbitals
must have been created. To
create three new orbitals we
require one s and 2 ps to become
blended. The hybridization is
therefore sp2
:N
N:
Sp
Now we will
consider how
multiple bonds
effect hybridization.
We can see here
that the electron
pairs are aligned in
three different
directions. The 4
electrons in the
double bond are all
aligned to the left
carbon and
therefore this only
counts as one
direction.
For a molecule of
N2 we can see that
the electron pairs
only align to two
directions this
means we need
two orbitals so the
atom is sp
hybridized.
CFU Ccall
What is the
hybridization of the
central atom (red)
in each molecule
a= sp
c = sp2
b,d,f, = sp3 e, h,i =
sp3d g, j,k=sp3d2
l=sp3d3
Which atom is sp2
hybridized?
Quick turn and talk
30 seconds
Teacher will cold
call students
Correct answer:
Carbonyl carbon or
carbonyl oxygen
It is important to
remember that the
other oxygen has
two lone pairs so is
sp3 hybridized