Lab #10 – Molecular Geometry
Background
Molecular model kits are a convenient way to study the three-dimensional structure of molecules. These kits
typically feature color-coded atoms to represent different elements: black for carbon, green for chlorine, etc…
We will be less interested in color coding than with the number of electron pairs surrounding each atom. We
will therefore use the yellow atoms to represent H atoms, not because they are yellow, but because they have 1
hole to represent the single electron pair that satisfies the H atom. We will use the black, four-holed atoms to
represent any atom that is bonding without an expanded octet. Expanded octets can be built by using the atoms
with five or six holes.
Procedure
You will build several 3-D molecular models by using the following procedure:
(1) Draw a Lewis structure for the molecule. Write resonance to indicate a resonance structure.
(2) Gather one yellow atom for each H atom in the molecule, and one black atom for every other atom (except
those with expanded octets).
(3) Gather 1 stick for each of the electron pairs in your Lewis structure.
(4) Assemble the atoms in such a way that every hole is filled with a stick.
(5) For each molecule, give the following information:
(i) The geometry around the central atom
(ii) The bond angles around the central atom
(iii) The polarity of the molecule
(iv) The hybridization around the central atom
(v) The total number of σ bonds and the total number of π bonds in molecule.
Data
CH4
Geometry
NH3
Bond angles
CH2Cl2
Geometry
Bond angles
Polar?
Hybrid.
Polar?
Hybrid.
σ bonds
π bonds
σ bonds
π bonds
Geometry
H2O2
Bond angles
Geometry
Bond angles
Polar?
Hybrid.
Polar?
Hybrid.
σ bonds
π bonds
σ bonds
π bonds
CH4O
Geometry
N2
Bond angles
H2O
Bond angles
Polar?
Hybrid.
Polar?
Hybrid.
σ bonds
π bonds
σ bonds
π bonds
Geometry
P4
Bond angles
H3O+
Polar?
Hybrid.
Polar?
Hybrid.
σ bonds
π bonds
σ bonds
π bonds
Geometry
C2H4
Geometry
Bond angles
Polar?
Hybrid.
Polar?
Hybrid.
σ bonds
π bonds
σ bonds
π bonds
Geometry
C2H2Br2
Bond angles
C2H2
Geometry
Bond angles
Bond angles
HF
Geometry
Geometry
Bond angles
Polar?
Hybrid.
Polar?
Hybrid.
σ bonds
π bonds
σ bonds
π bonds
SCN-
Geometry
Bond angles
Geometry
Bond angles
Polar?
Hybrid.
Polar?
Hybrid.
σ bonds
π bonds
σ bonds
π bonds
SO2
NO3-
Geometry
Bond angles
SO4-2
Bond angles
Polar?
Hybrid.
Polar?
Hybrid.
σ bonds
π bonds
σ bonds
π bonds
Geometry
HNO3
Bond angles
CO2
Polar?
Hybrid.
Polar?
Hybrid.
σ bonds
π bonds
σ bonds
π bonds
Geometry
SF6
Geometry
Bond angles
Polar?
Hybrid.
Polar?
Hybrid.
σ bonds
π bonds
σ bonds
π bonds
Geometry
OPN
Bond angles
XeF2
Geometry
Bond angles
Bond angles
CO3-2
Geometry
Geometry
Bond angles
Polar?
Hybrid.
Polar?
Hybrid.
σ bonds
π bonds
σ bonds
π bonds
Geometry
N2H4
Bond angles
Geometry
Bond angles
Polar?
Hybrid.
Polar?
Hybrid.
σ bonds
π bonds
σ bonds
π bonds
SO3
CN-
Geometry
Bond angles
I3-
Bond angles
Polar?
Hybrid.
Polar?
Hybrid.
σ bonds
π bonds
σ bonds
π bonds
Geometry
RnF4
Bond angles
BF3
Geometry
Bond angles
Polar?
Hybrid.
Polar?
Hybrid.
σ bonds
π bonds
σ bonds
π bonds
ClO2-
Geometry
Bond angles
N2F2
Geometry
Geometry
Bond angles
Polar?
Hybrid.
Polar?
Hybrid.
σ bonds
π bonds
σ bonds
π bonds
N3-
Geometry
Bond angles
Geometry
Bond angles
Polar?
Hybrid.
Polar?
Hybrid.
σ bonds
π bonds
σ bonds
π bonds