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Posted: Sun May 27, 2018 6:08 pm
by Cytlalli 1B
How do you know when a molecule has polarity or is it in every molecule? If so how do you determine which is positive and which is negative?

Re: Polarity

Posted: Sun May 27, 2018 6:59 pm
by Emma Leshan 1B
You have to look at the electronegativity of each element involved. Technically, every covalent bond has polarity unless it is between 2 of the same elements (O2 for example). However, some bonds are more polar (example: C-H bonds are less polar than O-H bonds) due to the differences in electronegativity between the 2 elements involved.

Re: Polarity

Posted: Sun May 27, 2018 8:10 pm
by Michael Park
It depends on the electronegativity of each atom in the molecule, so no it cannot be in every molecule. The trend for electronegativity increases up a group and across a period, so elements like fluorine, chlorine, and nitrogen have pretty high electronegativity. This means that they have a greater tendency to attract electrons. Since electrons are negatively charged, these atoms (of fluorine, chlorine, and nitrogen) will be slightly negative.

A good example of this is a water molecule. Oxygen is far more electronegative than hydrogen, so it attracts hydrogen's electrons a little closer to oxygen, which gives it a slightly negative charge.