Part D. Examine the three-dimensional structures of each of the following molecules in the simulation, which can be found in the Real Molecules mode. Then, identify which molecules are polar and which are nonpolar. Assume that every bond in each molecule is polar covalent. It may be easier to visualize if you uncheck the box labeled Show Lone Pairs.
Drag the appropriate items to their respective bins.
Molecular geometry impacts whether a molecule is polar. Polarity is important because polar molecules interact more strongly with each other (intermolecular interaction) than nonpolar molecules. This explains why nonpolar molecules tend to be gases at room temperature and why polar molecules tend to be liquids at room temperature. Stronger intermolecular forces require more energy to separate them from each other.
The molecular geometry and bond polarities both play critical roles in determining whether or not a molecule is polar. A polar molecule has a net dipole moment, which means that there is an uneven distribution of electrons across the entire molecular structure. This dipole moment is sometimes indicated by an arrow, which has a cross at the end of the lowest electron density (positive end) and points in the direction of the highest electron density (negative end). This dipole moment is achieved when the molecule's polar covalent bonds have an asymmetric orientation. Examine the structures of carbon dioxide and carbonyl sulfide below. Both molecules contain at least one polar covalent bond, but only CO2 is symmetric. The asymmetry in COS is due to oxygen being more electronegative than sulfur. As you can see, the symmetry in CO2 effectively cancels out all bond dipole moments, but a net dipole moment can exist in COS because of its asymmetry.
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