CH 115 Fall 2014
Worksheet 13
1. List the electronic geometry, molecular geometry, and bond angles for the central
atom (or other specified atom) of the following molecules.
a). COCl2 – trigonal planar, trigonal planar, 120o
b). ClF4+ - trigonal bipyramidal, see-saw, less than 90o, 120o, and 180o
c). SO2 – trigonal planar, bent, less than 120o
d). HCOOH (carbon) – trigonal planar, trigonal planar, 120o
e). IO4- - tetrahedral, tetrahedral, 190.5o
Remember the first step to doing these problems is to draw a Lewis structure!
2. What is hybridization theory? What is a hybrid orbital? What is its purpose? (Think
about why/how covalent bonds form). How do hybrid orbitals compare in energy to
atomic orbitals?
Hybridization is the process by which we mix atomic orbitals together to form
hybrid orbitals that more accurately describe bonding patterns observed for
certain molecules. Covalent bonds from through the overlap of these orbitals –
hybrid orbitals better describe the geometry and angles we predict when we
draw Lewis structures for compounds. Hybrid orbitals are intermediate in
energy, or an average of the energies of the orbitals that were mixed to form
them.
3. How do you determine the hybridization of an atom? What is the hybridization of
each of the central atoms in question #1?
1. Draw the Lewis structure
2. Count the regions of electrons density around the atom in question
3. Assign hybridization (sp, sp2, sp3, sp3d, sp3d2) based on the number of
regions
Question # 1:
a). sp2
b). sp3d
c). sp2
d). sp2
e). sp3
4. What is a sigma bond? Which orbitals can be used to form it? In the most likely
Lewis structure of SCN-, what two orbitals form the sigma bond between S and C?
A sigma bond is the same thing as a single bond. It is formed when two orbitals
overlap – those orbitals can be either atomic or hybrid orbitals depending on
the hybridization of the atoms that make up the bond.
Sigma bond between S and C is formed by sp3 and sp2 orbitals.
5. What is a pi bond? What orbitals can be used to form it? In the most likely structure
of CO2, what two orbitals form the pi bond between O and C?
A pi bond is a bond formed by the overlap ALWAYS of two unhybridized p
(atomic) orbitals. Between O and C – 2p and 2p make the pi bond ALWAYS
CH 115 Fall 2014
Worksheet 13
6. Fill in the table below.
Single Bond
Double Bond
Triple Bond
Sigma Bonds?
1
1
1
Pi Bonds?
0
1
2