Write Lewis structures and predict whether each of the...

Write Lewis structures and predict whether each of the following is polar or nonpolar. a. HOCN (exists as $\mathrm{HO}-\mathrm{CN}$ ) b. $\operatorname{COS}$ c. $\mathrm{XeF}_{2}$ d. $\mathrm{CF}_{2} \mathrm{Cl}_{2}$ e. $\mathrm{SeF}_{6}$ f. $\mathrm{H}_{2} \mathrm{CO}(\mathrm{C}$ is the central atom. $)$

Write Lewis structures and predict whether each of the following is polar or nonpolar.
a. HOCN (exists as $\mathrm{HO}-\mathrm{CN}$ )
b. $\operatorname{COS}$
c. $\mathrm{XeF}_{2}$
d. $\mathrm{CF}_{2} \mathrm{Cl}_{2}$
e. $\mathrm{SeF}_{6}$
f. $\mathrm{H}_{2} \mathrm{CO}(\mathrm{C}$ is the central atom. $)$

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Key Concepts

Bond Polarity

Bond polarity results from differences in electronegativity between two bonded atoms, leading to an unequal sharing of electrons. Recognizing which bonds are polar is a key step in predicting the overall dipole moment and polarity of the molecule.

Polarity Determination

The overall polarity of a molecule is the combined effect of the individual bond polarities and the molecular geometry. Even with polar bonds, a symmetrical arrangement may result in the cancellation of dipole moments, rendering the molecule nonpolar, whereas an asymmetrical arrangement tends to produce a net dipole moment and a polar molecule.

Lewis Structures

Lewis structures represent the valence electrons of atoms within a molecule, showing how atoms are bonded together and indicating lone pairs. They are essential for determining the connectivity and potential charge distribution within the molecule, which further informs the discussion of molecular geometry and overall polarity.

Molecular Geometry

Molecular geometry is the three-dimensional arrangement of atoms in a molecule, usually predicted using VSEPR theory. The shape of a molecule is crucial because it determines whether the dipole moments from individual polar bonds will cancel or add up to produce a net dipole moment, thus defining the molecule as polar or nonpolar.

Transcript

00:01 Our examples of our structures here.

00:02 So the first one, we can see it is linear and so we have bond angles of about 180 degrees there.

00:09 We do have a small dipole in the direction of the oxygen as is asymmetric.

00:14 And then looking at our next example here, we do have a small dipole again.

00:19 And because it is linear, we are experiencing those 180 degree bond angles again because we have our sp2 planar hybridised centres.

00:28 And now if we move, on to our xenon example here.

00:33 So as you could imagine, xenon has three loan pairs.

00:36 It is group eight, it is a noble gas.

00:39 And so we have one lone pair going away from us, one loan pair coming towards us, and then another in the plane.

00:47 So i hope that helps you understand why it is linear.

00:52 And we have dipoles present.

00:56 We have dipoles in the direction of our fluorine.

00:59 Now, fluorine is the most electronegative atom in the table.

01:05 And so we have our individual dipoles.

01:08 However, because the molecule is symmetric, they cancel.

01:13 And we have no net dipole.

01:15 This molecule is not polar.

01:17 So now moving on to our tetrahedral example here, we have bond angles of about 109 .5.

01:27 And we have two fluorines and two chlorine atoms here...

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