Hybridization and Other Good Stuff
Introduction
• A hybrid results from combining two of
the same type of objects, and it has
characteristics of both
• Atomic orbitals undergo hybridization
during bonding
• Consider the methane molecule
Methane
• CH4
• The electron configuration of C is
1s22s22p2
• You might expect the two unpaired p
electrons to bond with other atoms and
the 2s electrons to remain as a lone pair
Visual
Carbon Hybridization
• This does not happen as we know carbon
forms 4 bonds
• Hybridization: a process in which atomic
orbitals are mixed to form new, identical
hybrid orbitals
• Each hybrid orbital contains one electron
that it can share with another atom
Visual
Name of the Orbitals
• The orbitals are made from one s orbital and
three p orbitals
• The name of the orbitals in methane is sp3
Geometry
• According to VSEPR, a tetrahedral shape
minimizes repulsion between the orbitals
Boron Trifluoride
• Consider BF3
• VSEPR predicts a trigonal planar shape
• To have this shape, one s and two p
orbitals on the boron must mix to form 3
identical sp2 hybrid orbitals
• Notice that one p orbital is unoccupied
sp2
sp
• Consider BeF2
• Electron configuration of Be is 1s22s2
• Beryllium must promote one electron to
the 2p orbital
• This results in sp hybridization and a
linear shape
BeF2
sp hybrid orbital of Be
More Information
• Lone pairs can occupy hybrid orbitals
• Consider water: it forms sp3 hybrid
orbitals and the two lone pairs on the
oxygen atom are in two of the hybrid
orbitals
To Determine Hybridization
• Count the total number of areas of
electron density on the central atom
• Be sure to include lone pairs and each
bond (whether single, double, or triple)
as one area
• 4 areas of electron density = sp3
• 3 areas of electron density = sp2
• Two areas of electron density = sp
Organic Molecules
• Consider ethane (C2H6), ethene (C2H4),
and ethyne (C2H2)
• Draw each Lewis structure
• Determine the type of hybridization each
carbon has
Ethane
• Lewis structure:
• Hybridization: sp3
Ethene
• Lewis structure
• Hybridization: sp2
Ethyne
• Lewis structure
• Hybridization: sp
Sigma Bond (σ
• Sigma bond: occurs when the electron
pair is shared in an area centered
between the two atoms
• The atomic orbitals (could be hybrids)
overlap end-to-end
• Electron density is at is greatest on the
internuclear axis (an imaginary line
joining the two nuclei)
More
• Single bonds are sigma bonds
Pi Bond (π)
• Pi bond: formed when parallel orbitals
overlap to share electrons
• High electron density is found above and
below the inter-nuclear axis (not on it)
• A double bond consists of one sigma
bond and one pi bond
• A triple bond consists of one sigma bond
and two pi bonds
Comparison
Isomerism
• Isomer: species with the same formula
but different properties
• The different properties are due to
different arrangements of atoms
• There are two main types of isomerism:
structural isomerism and
stereoisomerism
Structural Isomerism
• The isomers contain the same atoms but
one or more bonds differ
Stereoisomerism
• Where all the bonds in the isomers are
the same but the spatial arrangements of
the atoms are different
Complex Metal Ions
• Complex ion: has a metal ion at its center
with a number of other molecules or ions
surrounding
• Can be considered to be attached to the
central ion by coordinate covalent bonds
• Ligands: the molecules or ions
surrounding the central metal ion
Simple Ligands
• The most common simple ligands include
water, ammonia, and chloride ions
• Coordination number: the number of
ligands surrounding the central metal ion
• Some coordination numbers:
• Water: 6; ammonia: 4; chloride ions: 4
Examples