Vsepr Theory & Hybridization Cont. Wood County Schools Page 2
ADVERTISEMENT
1
2
3VSEPR T
& h
.
hEoRy
ybRidizaTion conT
Hybridization
Hybridization explains the formation of
Types of Hybridized Orbitals
bonds as the overlap of atomic orbitals and
is a central part of the valence bond theory.
Orbitals Hybridized
Hybridized
Number of Hybridized
Hybridized orbitals are formed by mixing
Orbital Names
Orbitals
atomic orbitals.
s + p
sp
2
•
The number of hybridized orbitals equals
s + p + p
sp
3
2
the number of atomic orbitals used to
s + p + p + p
sp
4
3
form the hybridized orbitals.
s + p + p + p + d
sp
d
5
3
•
Each hybridized orbital contains two
electrons.
s + p + p + p + d + d
sp
3
d
2
6
Consider the molecule CH
with the electron configuration 1s
2s
2p
. The carbon atom forms four bonds, but in the
2
2
2
4
ground state electron configuration, carbon only has two half-filled orbitals (the 2p orbitals). In order to form four
bonds, one of the electrons in the 2s orbital must be promoted to the empty 2p orbital, creating four half-filled orbitals.
Image Credit: CK-12 Foundation, CC-BY-NC-SA 3.0
If the four hydrogen atoms bonded to the atomic orbitals as is, then one of the bonds would be different from the
others. In reality, all the bonds are identical. Hybridization explains this observation by creating four identical sp
3
orbitals. This is beneficial for an atom because it lowers the energy state of the higher-energy orbitals and makes all
orbitals have an equal energy level, thus assisting bonding patterns (each orbital can make one chemical bond).
Sigma and Pi Bonds
Hybridized and unhybridized orbitals can then combine to form molecular orbitals that belong to the entire molecule.
The two types of molecular orbitals are sigma bonds and pi bonds.
Figure: Sigma and pi bonds
Image Credit: Rory Runser, CC-BY-SA 3.0
•
Each molecular orbital still holds only two electrons.
•
Sigma (σ) bonds form from the head-on-head overlap of s, p, or hybridized orbitals. All covalently bonded molecules
contain sigma bonds.
•
Pi (�) bonds form from the side-by-side overlap of unhybridized p orbitals.
•
Double bonds have 1 sigma and 1 pi bond, while triple bonds have 1 sigma and 2 pi bonds.
•
Sigma bonds are stronger than pi bonds.
Polar Molecules
The shape of the molecule can be used to determine if the molecule is polar. To see if a molecule is polar or nonpolar,
1. Draw the molecular geometry
2. Label the bonds with arrows that point toward the more electronegative atom
3. If all the arrows cancel out, then the molecule is nonpolar. Otherwise, the molecule is polar.
Imagine the arrows are pushing on the molecule. If the overall effect of all the arrows cause the molecule to
move in one direction, the molecule is polar. If the molecule doesn’t move, the molecule is nonpolar.
Notes
Page 2 of 3
ADVERTISEMENT
0 votes
Related Articles
Related forms
Related Categories
Parent category: Education