Polarizable vs Polarizing Power

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Eric Cruz 2G
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Polarizable vs Polarizing Power

Postby Eric Cruz 2G » Sat Nov 07, 2020 11:49 pm

I am still confused about polarizability and polarizing power. Does polarizability relate exclusively to anions and polarizing power relate exclusively to cations? If so, does the polarizability of anions occur because of the polarizing power of cations? I understand it relates to distortion of electrons and its proximity to acting like a covalent bond, but I'm not sure how to use polarizability and polarizing power to explain this occurrence.

Hannah Biju 1E
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Re: Polarizable vs Polarizing Power

Postby Hannah Biju 1E » Sat Nov 07, 2020 11:52 pm

If two oppositely charged ions are brought together, the nature of the bond between them depends upon the effect of one ion on the other. The ability of a cation to distort an anion is known as its polarization power and the tendency of the anion to become polarized by the cation is known as its polarizability.

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Re: Polarizable vs Polarizing Power

Postby Silvi_Lybbert_3A » Sun Nov 08, 2020 2:53 am

Hi! It seems as though cations are usually polarizing, while the anion is polarizable because cations tend to distort anions; however, I believe that it is possible for it to be the other way around and will explain this below.
I would assume that polarizability does not relate exclusively to anions, nor does polarizing power relate exclusively to cations. In the example in lecture, NaI salt has iodine as the polarizable anion. However, if you take an example, such as potassium fluoride (PF), the anion (fluoride) would be a polarIZING anion because it has the power to distort the electrons of potassium. This is because in this example potassium is the larger atom with its electrons held less tightly, and therefore the electrons of the potassium would be the ones to be distorted (highly polarizable) and potassium would be a polariZABLE CATion. This example compared to the example from lecture (NaI) shows that polarizability/polarizing power is not exclusive to anions/cations.
You can also look to see whether an ion will be polarizable or polarizing based on their levels of polarizing power (for ex/ Dr. Lavelle made this clear by comparing polarizing power of Li+ and Cs+ cations and cations with +3 charge and +1 charge; Cs+ is bigger with lower charged density and therefore has lower polarizing power, and a cation with +1 charge has a lower polarizing power than a cation with a +3 charge because it has a lower electrostatic pull on the electrons of the anion). I believe you can compare the cation's level of polarizing power with that of the anion's to determine which is the polarizing ion.
Hope that helps!

Ellison Gonzales 1H
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Re: Polarizable vs Polarizing Power

Postby Ellison Gonzales 1H » Sun Nov 08, 2020 7:38 pm

Polarizable is the ability to GET pulled (which is the anion pulled by the positive charge).
Polarizing power is the cation’s ability TO pull the anions into the shared region.

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