Embed Size (px)
Citation preview
AP Chemistry 2014-2015
CH 9 COVALENT BONDING ORBITALS
The localized electron model (from Chapter 8) views a molecule as a collection of atoms bound together by sharing electrons between their atomic orbitals. For example, methane (CH4) consists of one carbon atom bonded to four hydrogen atoms.
HYBRIDIZATION AND THE LOCALIZED ELECTRON MODEL
According to the orbital diagram for carbon, there are four valence electrons—two in the 2s subshell, and two in the 2p subshell. One of the 2s electrons can get “promoted” to the 2p subshell. This move allows carbon to form four bonds, one to each hydrogen. However—this would mean that the four C-H bonds are not identical. Experimental observations show that the four C-H are identical, so this model does not correctly explain every aspect of bonding.
We can modify it, though, so that carbon’s 2s and three 2p orbitals “hybridize” to form four identical sp3 orbitals.
OVERVIEW OF HYBRID ORBITALS
Type of Hybridization
Orbital Composition
Number of Electron Domains
Common Molecular
Geometries
sp 1 s1 p 2 Linear
sp2 1 s2 p 3 Trigonal planar
Bent
sp3 1 s3 p 4
TetrahedralTrigonal
pyramidalBent
dsp3 (also sp3d)1 s3 p1 d
5
Trigonal bipyramidal
See-sawT-shaped
Linear
d2sp3 (also sp3d2)
1 s3 p2 d
6
OctahedralSquare pyramidal
Square planarT-shaped
Linear
Hybridization of one s orbital and one p orbital
Two electron domainsUsually occurs when an atom either a)
forms double bonds to two different atoms (ex. CO2) or b) forms a single bond to one atom and a triple bond to another atom (ex. HCN). One exception to this is beryllium hydride, BeH2.
Ex. CO2, HCN, C2H2, N2, BeH2
SP HYBRIDIZATION
Hybridization of one s orbital and two p orbitals
Three electron domainsUsually occurs when an atom forms single
bonds to two atoms, and a double bond to a third atom (ex. CH2O). One exception to this is boron trifluoride, where boron forms single bonds with three atoms (no double bonds).
Ex. C2H4, CH2O, BF3
SP2 HYBRIDIZATION
Formed by the hybridization of one s orbital and three p orbitals
Four electron domainsEx. CH4, NH3, H2O
SP3 HYBRIDIZATION
Hybridization of one s orbital, three p orbitals, and one d orbital
Five electron domainsEx. PCl5, I3
-
DSP3 HYBRIDIZATION
Hybridization of one s orbital, three p orbitals, and two d orbitals
Six electron domainsEx. SF6
D2SP3 HYBRIDIZATION
FOR EACH OF THE FOLLOWING
MOLECULES, WRITE THE LEWIS STRUCTURE,
PREDICT THE MOLECULAR
STRUCTURE, GIVE THE EXPECTED HYBRID ORBITALS ON THE
CENTRAL ATOM, AND PREDICT THE OVERALL
POLARITY.
Molecule Lewis Structure
Molecular Structure
Hybridization of Central Atom
Overall Polarity
NF3
TeF4
Molecule Lewis Structure
Molecular Structure
Hybridization of Central Atom
Overall Polarity
KrF2
SeF6
Molecule Lewis Structure
Molecular Structure
Hybridization of Central Atom
Overall Polarity
IF3
DETERMINE THE HYBRIDIZATION OF EACH ATOM IN THE FOLLOWING
MOLECULES.
DETERMINE THE HYBRIDIZATION OF EACH ATOM IN THE FOLLOWING
MOLECULES.
