Molecular Polarity (Simplified) - Video Tutorials & Practice Problems
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Polarity happen in molecules when there is an unequal sharing of electrons.
Molecular Polarity
Both a molecule's shape and bond polarity can affect its overall polarity.
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concept
Molecular Polarity (Simplified) Concept 1
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recall that the polarity of chemical bonds arises from unequal sharing of electrons between atoms based on electro negativity. We're going to say here that when we say molecular polarity thing means we're talking about polarity that arises from an entire co valent molecule. And with this idea we have non polar versus polar molecules. Non polar molecules are any hydrocarbon. So compounds composed of only carbon and hydrogen and any non hydrocarbon with a perfect shape. Now an element or not, actually a compound has a perfect shape when the central element has zero lone pairs and the same surrounding elements, if you break either one of those, then you're classified as a polar molecule. So that's any lewis dot structure that doesn't have a perfect shape. So if we take a look here, We have 2-4 electron groups. In the first column, all of these shapes have zero lone pairs on the central element and it's assumed that all the surrounding elements would be the same. So in these situations, all of these molecules would be non polar. Once we start going into the central element having one lone pair to lone pairs, etcetera, then all of these are classified as polar molecules. They're no longer perfect shapes. So again, to be a perfect shape, your central element has to have zero lone pairs, and the surrounding elements must be the same.
Nonpolar Molecules posses perfect shape, while polar molecules do not.
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example
Molecular Polarity (Simplified) Example 1
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determine if carbon tetrachloride, CCL four is polar or non polar. All right. So we have carbon which is in group for A and Corey, which is in group seven A and R. Four of them Giving us 32 valence electrons. Tour carbon won't go in the center. You would form single bonds with the chlorine. Remember the surrounding elements have to follow the octet rule. So we put enough electrons around them to do that. Okay, And that takes care of our 32 valence electrons. Now we're going to say here that we have a molecule basically that we've drawn that has four bonding groups. Remember bonding groups are just your surrounding elements and it has zero lone pairs here are central element, has no lone pairs and we have the same surrounding elements. So this is a perfect shape since it's a perfect shape, that means a molecule will be non polar.
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Problem
Problem
Determine if the compound of BCl2F is polar or nonpolar.
A
polar
B
nonpolar
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Problem
Problem
Determine if phosphorus trihydride, PH3, is polar or nonpolar.
A
polar
B
nonpolar
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Problem
Problem
Determine if difluorine selenide, F2Se, is polar or nonpolar.
A
polar
B
nonpolar
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Problem
Problem
Determine if carbon dioxide, CO2, is polar or nonpolar.
A
polar
B
nonpolar
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