NAME: ________________________________________________
REGENTS CHEMISTRY
CHEMISTRY LAB
July 11, 2016
MR. SCIAME
COVALENT MOLECULES
BACKGROUND:
A single covalent bond consists of a pair of shared electrons. When such a pair is equally shared between identical
atoms, the bond is pure covalent (non-polar). However, unequal sharing of electrons between different atoms produces a
bond that is to some degree polar. The degree of polarity of the bond can be represented by its percentage of ionic
character. This percentage can be calculated using the electronegativity difference between the bonded atoms.
Remember, electronegativity is a measure of the attraction that atom has for the electrons involved in a bond.
Covalently bonded atoms produce molecules that may be polar or non-polar. If two different atoms (diatomic molecule)
are covalently bonded, the compound’s molecule must be linear and somewhat polar. However, if two identical atoms are
bonded, the molecule is still diatomic but non-polar. More complex compounds have molecules which may be polar or
non-polar depending on the symmetry of the molecule. Even though a molecule might contain polar bonds, the molecule
can be non-polar if the atoms are evenly spaced (highly symmetrical). Less symmetrical molecules for compounds that
are bent (nonlinear) or trigonal pyramids will be polar.
PURPOSE:
To identify 15 unknown molecules by determining bond shape, shape of molecule, and polarity.
MATERIALS:
Molecular molecule kit
PROCEDURE:
You will look at models for 15 different compounds. You will try to identify the models based on the following:
A) Shape. Is it linear, bent, a pyramid (3 pointed), or tetrahedral (4 pointed).
B) Atoms. They differ by color and number of holes.
C) Type and number of bonds.
You will work in groups. You will have one minute to look at the molecule in front of you. Note its characteristics. After
observing all 15 molecules, try to identify each.
MOLECULE LIST:
CH3Br, O2, Cl2, CCl4, CO2, BrCl, NH3, HBr, HCl, H2O, CH3Cl, H2S, H2, N2, CH4
DATA:
You will fill out the data sheet and include it as page 2 of your lab report.
QUESTIONS:
1. In the molecule kit, what did the wooden pegs represent? What did the springs represent?
2. What does the number of holes in each atom represent?
3. Identify the shape and type of molecule of the following:
A. SO2
B. Br2
C. PCl3
UNKNOWN
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
FORMULA
LEWIS (ELECTRON
DOT) STRUCTURE
POLAR OR
NONPOLAR BOND
SHAPE OF
MOLECULE
POLAR OR NONPOLAR
MOLECULE