Polarizability vs Polarizing Power in anions/cations & bonding

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DanielHong2L
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Polarizability vs Polarizing Power in anions/cations & bonding

Postby DanielHong2L » Wed Nov 18, 2020 9:41 pm

What exactly is polarizability and polarizing power?

I understand that polarizability has to do with an anion's ability to take away electrons (correct me if I'm wrong)

But in the intermolecular energy equation, it uses the polarizability of two atoms and their polarizability which would mean that high polarizability would equal easily distorted(?)

In essence my question is:

What exactly is polarizability
What exactly is polarizing power

Is polarizability's definition different for intermolecular energy equation?

Thank you!

Marisa Gaitan 2D
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Re: Polarizability vs Polarizing Power in anions/cations & bonding

Postby Marisa Gaitan 2D » Wed Nov 18, 2020 9:49 pm

Large anions are typically highly polarizable, meaning they are likely to have their electrons distorted. So think I-, Br-. This is because their electrons are not as tightly bound to the nucleus, and are pulled away by polarizing cations. Small, highly charged cations like Al3+ have the large polarizing power. This allows them to attract electrons from anions (especially anions that are highly polarizable) and thus distorting the electron cloud.

Kelly Tran 1J
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Re: Polarizability vs Polarizing Power in anions/cations & bonding

Postby Kelly Tran 1J » Thu Nov 19, 2020 12:42 am

Polarizability refers to the ability of the anion's electrons to be distorted or pulled into the shared/bonding region. Large anions are highly polarizable. Polarizing power refers to the cation's ability to pull (distort) the anion's electrons into the shared/bonding region. Small, highly charged cations have high polarizing power.

Jenaye Brelland 2I
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Re: Polarizability vs Polarizing Power in anions/cations & bonding

Postby Jenaye Brelland 2I » Thu Nov 19, 2020 2:00 am

I'm glad you asked this question. I was also confused on this. So polarizing power is the ability to take away an electron (by a cation) and polarizability is the probability or ability to have electrons be taken away (from a anion)?

Mackenzie Stockton 2H
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Re: Polarizability vs Polarizing Power in anions/cations & bonding

Postby Mackenzie Stockton 2H » Thu Nov 19, 2020 3:54 pm

Polarizability pertains to the anion. It is a measure of how easily their electrons can be distorted (and moved into the shared region, which is on the internuclear axis between two atoms in a bond). Larger anions have more electrons that are not as closely held to the nucleus, so they are more polarizable because it is easier for their electrons to be pulled away from their nucleus into the shared region of the bond, giving covalent character to an ionic bond.

Polarizing power pertains to the cation. It is a measure of how strong the cation can "pull" the electrons from the anion into the shared region of electron density. Smaller cations (which have a higher charge density, a measure of how much charge is present in the area of the cation) with higher charges (like +2) have more polarizing power, because they can pull the electrons very efficiently from the anion into the shared region.

DanielHong2L
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Re: Polarizability vs Polarizing Power in anions/cations & bonding

Postby DanielHong2L » Thu Nov 19, 2020 6:08 pm

Mackenzie Stockton 2H wrote:Polarizability pertains to the anion. It is a measure of how easily their electrons can be distorted (and moved into the shared region, which is on the internuclear axis between two atoms in a bond). Larger anions have more electrons that are not as closely held to the nucleus, so they are more polarizable because it is easier for their electrons to be pulled away from their nucleus into the shared region of the bond, giving covalent character to an ionic bond.

Polarizing power pertains to the cation. It is a measure of how strong the cation can "pull" the electrons from the anion into the shared region of electron density. Smaller cations (which have a higher charge density, a measure of how much charge is present in the area of the cation) with higher charges (like +2) have more polarizing power, because they can pull the electrons very efficiently from the anion into the shared region.


This made perfect sense thank you so much!

Angel More
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Re: Polarizability vs Polarizing Power in anions/cations & bonding

Postby Angel More » Thu Nov 19, 2020 6:17 pm

To add on in terms of periodic trends

Polarizability decreases as it goes across a period and increases as it goes down a group.
This is because the greater the number of electrons, the less control the nuclear charge has on charge distribution, and thus the increased polarizability of the atom. As you go across the number of electron shells is the same (with a growing number of protons) across a period but increases when moving down a group.

On the other hand Polarizing Power increases as it goes across a period and decreases as it goes down a group. Small cations are highly charged and thus have high polarizing power. As you go across the nucleus decreases, increasing the polarizing power and when you go down the nucleus increases, deceasing the the polarizing power.

Xavier Herrera 3H
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Re: Polarizability vs Polarizing Power in anions/cations & bonding

Postby Xavier Herrera 3H » Sat Nov 21, 2020 12:17 pm

Polarizability is how easy it is to distort the electrons in an ion. A large anion like Te2- would be highly polarizable because it has many shells of electrons, making the outer electrons easy to distort due to shielding. A small, highly charged cation like B3+ is very polarizing because its high charge and small size allows it to easily pull electrons from other anions.

Jason Knight - 1F
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Re: Polarizability vs Polarizing Power in anions/cations & bonding

Postby Jason Knight - 1F » Sat Nov 21, 2020 2:41 pm

Polarizability measures trends of how easily an electron cloud is distorted by an electric field. For example, the more energy shells equals more polarizability. Polarizing power is the tendency of an anion to become polarized by the cation. A more positive charge means a greater polarizing power.

Chloe Shamtob 2H
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Re: Polarizability vs Polarizing Power in anions/cations & bonding

Postby Chloe Shamtob 2H » Sat Nov 21, 2020 2:55 pm

A good rule of thumb is that the smaller and more highly charged a cation is the higher polarizing power it has. Polarizing power refers to the cation's ability to pull the anion's electrons into the shared/bonding region distorting them from the original anion. When looking at polarizability, larger anions are highly polarizable by cations. Polarizability is the ability of the anion's electrons pulled into the shared region. The larger the anion the easier it is for the cation to distort the anions electrons.

Jenaye Brelland 2I
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Re: Polarizability vs Polarizing Power in anions/cations & bonding

Postby Jenaye Brelland 2I » Sun Dec 06, 2020 4:57 pm

apples wrote:To add on in terms of periodic trends

Polarizability decreases as it goes across a period and increases as it goes down a group.
This is because the greater the number of electrons, the less control the nuclear charge has on charge distribution, and thus the increased polarizability of the atom. As you go across the number of electron shells is the same (with a growing number of protons) across a period but increases when moving down a group.

On the other hand Polarizing Power increases as it goes across a period and decreases as it goes down a group. Small cations are highly charged and thus have high polarizing power. As you go across the nucleus decreases, increasing the polarizing power and when you go down the nucleus increases, deceasing the the polarizing power.

Thank you! The bold sentences helps!


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