Question

activity b (continued from previous page)

1. classify: with the gizmo, test and categorize the remaining molecules. report your findings.

polar molecules
nonpolar molecules
did the polarity of any of these molecules surprise you? explain.

1. explain: drag the ccl₄ molecule into the simulation area.

a. does this molecule contain polar or nonpolar bonds?
b. turn on the electric field. why do you think the molecule does not rotate in this field?
if a molecule is symmetrical, the effect of the partial charges on either side cancel out. in this case, even though it contains polar bonds, the molecule as a whole may be nonpolar.
c. what other nonpolar molecule contains polar bonds?

1. challenge: drag the ocl₂ molecule into the simulation area. turn on show valence electrons. what do you notice at the very top of the oxygen atom, and how does this feature explain why the molecule is polar?

in an ocl₂ molecule, the top of the oxygen atom contains two lone pairs of electrons. this gives the oxygen end of the molecule a slight negative charge and the chlorine end a slight positive charge.

Explanation:

Step1: Analyze CCl₄ bonds

The C - Cl bonds in CCl₄ are polar due to electronegativity difference between C and Cl. But the molecule is tetrahedral and symmetrical, so the bond dipoles cancel out.

Step2: Explain non - rotation in electric field

In CCl₄, although it has polar bonds, the molecule's symmetry causes the overall dipole moment to be zero. So, in an electric field, there is no net force to cause rotation as the partial charges are symmetrically distributed and cancel each other out.

Step3: Find other non - polar molecules with polar bonds

CO₂ is a non - polar molecule with polar C=O bonds. The linear shape of CO₂ makes the bond dipoles cancel each other.

Step4: Analyze OCl₂ polarity

In OCl₂, the oxygen atom has two lone pairs of electrons at the top. These lone pairs create an uneven distribution of electron density. The lone pairs repel the bonding pairs, making the molecule bent. This results in a net dipole moment, with the oxygen end being slightly negative and the chlorine end being slightly positive, making the molecule polar.

Answer:

1. A. Polar bonds

B. The molecule is symmetrical (tetrahedral), so the overall dipole moment is zero and there is no net force to cause rotation in the electric field.
C. CO₂

1. At the very top of the oxygen atom, there are two lone pairs of electrons. These lone pairs create an uneven electron - density distribution, making the oxygen end slightly negative and the chlorine end slightly positive, thus making the OCl₂ molecule polar.