Ionic radii

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Marni Kahn 1A
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Ionic radii

Postby Marni Kahn 1A » Wed Oct 16, 2019 4:17 pm

Why do ionic radii generally increase down a group?

Kaitlyn Ang 1J
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Re: Ionic radii

Postby Kaitlyn Ang 1J » Wed Oct 16, 2019 4:24 pm

As the atoms go down a group, there are more electron levels added and the valence electrons (the outer shell of electrons) gets farther away from the nucleus, which not only increases the radius because there are more electron levels in between, but the attraction that binds the electrons and nucleus together lessens, which creates a greater atomic radius

Benjamin Feng 1B
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Re: Ionic radii

Postby Benjamin Feng 1B » Wed Oct 16, 2019 4:27 pm

As you go down a group, the principle quantum number, n, increases, which means that the distance from the nucleus of the outermost valance electrons also increases. This is also the case for atomic radii as well.

Astrid Lunde 1I
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Re: Ionic radii

Postby Astrid Lunde 1I » Wed Oct 16, 2019 5:05 pm

As you go down the group the number of electrons increases for each atom. You then get more shells and the valence electrons in the outermost shell get farther away from the nucleus.

KaitlynBali_4B
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Re: Ionic radii

Postby KaitlynBali_4B » Sat Oct 19, 2019 11:59 pm

One other thing to note is that as you go down a group, the number of protons in an atom also increases. Repulsion from the positive nuclei in ionic compounds also slightly contributes to larger ionic radii.

John Arambulo 1I
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Re: Ionic radii

Postby John Arambulo 1I » Sun Oct 20, 2019 11:20 am

As you go down a group, the radius increases because the principal quantum number (n) increases, but you have you take more into account. The nuclear charge increases because there are more protons pulling electrons, but the effective nuclear charge is affected because the electron-electron repulsions push the radius further out as well as the electron shielding from the inner levels and subshells causing the attraction of the valence electrons to the positively charged nucleus to be weaker. Thus, the ionic radius increases as you go down a group.

Ruby Richter 2L
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Re: Ionic radii

Postby Ruby Richter 2L » Mon Oct 21, 2019 4:12 pm

I know ionic and atomic radius follow the same trend in the periodic table increasing down the group and decreasing across a period, but does the covalent radius also follow this trend? Lavelle mentioned it in class but I was confused about the trend it follows.

selatran1h
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Re: Ionic radii

Postby selatran1h » Mon Oct 21, 2019 9:04 pm

Ionic radii increase down a group due to the fact that, since electrons are added to valence shells, these additional shells are further from the nucleus, increasing the ionic radius of the atom.

Rebecca Epner 4A
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Re: Ionic radii

Postby Rebecca Epner 4A » Mon Oct 21, 2019 9:08 pm

Ruby Richter 4G wrote:I know ionic and atomic radius follow the same trend in the periodic table increasing down the group and decreasing across a period, but does the covalent radius also follow this trend? Lavelle mentioned it in class but I was confused about the trend it follows.

I believe covalent radii follow the same trends because as you move down a group, additional shells are still being added which would increase the radii. Conversely, as you move across the period, electrons are being added in the same shell, decreasing the radii regardless of the type of bond.
But someone please correct me if I'm wrong! This is just based on what I understood from today's lecture.

Kimberly Bauer 4E
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Re: Ionic radii

Postby Kimberly Bauer 4E » Tue Oct 22, 2019 12:16 am

I have a question regarding whether it's a cation or anion. Does that affect the ionic radius of the element? In my notes, I wrote "cations are smaller than their parent atoms and anions are larger"

Mariah
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Re: Ionic radii

Postby Mariah » Tue Oct 22, 2019 12:42 pm

Kimberly Bauer 4E wrote:I have a question regarding whether it's a cation or anion. Does that affect the ionic radius of the element? In my notes, I wrote "cations are smaller than their parent atoms and anions are larger"


I wrote the same, I think they do have an effect on the radius of an element, but I don't understand how we could find those numbers? They are given right?

Daniel Honeychurch1C
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Re: Ionic radii

Postby Daniel Honeychurch1C » Tue Oct 22, 2019 6:30 pm

The actual values of the atomic radius are always given. You just need to know that cations are smaller than their parent atoms because they have less electrons which means there is less electron repulsion. Anions are larger than their parent atoms because they have more electrons and thus more electron repulsion.


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