Gen Chem Destroyer Question

[una09]

Advertisement - Members don't see this ad

Question 203,

The answer is, Sr++ is smaller than S--, why? I understand that cations are smaller than anions but Sr is two periods below S, shouldn't it automatically be bigger than S? Also Sr++ is probably around Kr, whereas S-- has a size close to Ar. Kr is one whole period below Ar, should it not be larger than Ar?

 

[loveoforganic]

I'd agree with your reasoning.

 

[americanpierg]

I never did understand when they were several periods apart too, until I found this website.

http://www.chemicool.com/elements/

Best you just go on there and spend 10 minutes checking out all the radii and and get a good feel for them. S2- has a larger radius than any of the 2+ akali earth metal ions

 

[una09]

I never did understand when they were several periods apart too, until I found this website.

http://www.chemicool.com/elements/

Best you just go on there and spend 10 minutes checking out all the radii and and get a good feel for them. S2- has a larger radius than any of the 2+ akali earth metal ions

Thanks!
I wish they gave an actual reason as to why the 2- anions in group six have very large radii.

 

[americanpierg]

Thanks!
I wish they gave an actual reason as to why the 2- anions in group six have very large radii.

It's actualy not just the elements in group 6. i actually spent like an hour looking it through, and any natural anions in groups 6 and 7 with an atomic number higher than sulfur are larger than any alkali earth metal cations. Te and above in groups and 7 are larger than any akali metals and earth metals cations. Ra2+ is larger than any akali metals below K+, and almost as large as Rb+. seems like the higher the atomic numbers, the greater discrepencies. F is barely larger than Na, I is a whole lot larger than Cs. At higher atomic numbers, Group 6 and Group 7 anions are almost the same size. Seems to be a trend of similar sizes 2 periods apart. Subsequent losses in electrons have a much more tremendous effect on the size of an atom than subsequent addition of electrons.

Also found out the nitrogen group can lose 3 electrons but cant gain 3. learn something new everyday...