atoms decreasing size Barrons DAT book

[yankeefan86]

Ok guys heres a problem in Barron's DAT book.

Which of the following shows atoms and ions in order of decreasing size?

A. Ar > Cl-> S^-2 >k+
B. K+ >s-2> Cl- > Ar
C. S-2> Cl+> Ar> k +
d. S-2> Ar >Cl-> K+
E. K+ > Ar > S-2 > Cl-

the answer is B
from my understanding aren't negative ions larger than positive ions?

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[qkchen]

Ok guys heres a problem in Barron's DAT book.

Which of the following shows atoms and ions in order of decreasing size?

A. Ar > Cl-> S^-2 >k+
B. K+ >s-2> Cl- > Ar
C. S-2> Cl+> Ar> k +
d. S-2> Ar >Cl-> K+
E. K+ > Ar > S-2 > Cl-

the answer is B
from my understanding aren't negative ions larger than positive ions?

could just be a typo. i agree that K+ shoiuld be the smallest ion in choice B

 

[yappy]

I agree with you. Cations are smaller than the neutral species because when electron is stripped there is more positive charge felt by the remaining electrons increasing the magnitude of the attractive forces.

 

[bharat008]

Ok guys heres a problem in Barron's DAT book.

Which of the following shows atoms and ions in order of decreasing size?

A. Ar > Cl-> S^-2 >k+
B. K+ >s-2> Cl- > Ar
C. S-2> Cl+> Ar> k +
d. S-2> Ar >Cl-> K+
E. K+ > Ar > S-2 > Cl-

the answer is B
from my understanding aren't negative ions larger than positive ions?

The answer is none of the above. All of them are incorrect.
Here it goes, from largest to smallest atoms -
S2->Cl->Ar>K+

In this question, if you look at electrons then all of them have same # of electrons, so you can't say that as electron cloud increases the atoms size increases. Therefore, use the # of protons; as they increase they would pull the electrons towards it making the atom smaller in size. For example, out of all those atoms K+ has 19 protons therefore they will pull the electrons with much more strength compared to all others, making the atom smaller.

Hope this helps...👍

 

[yankeefan86]

thanks guys, I really appreciate it. I was going crazy when I was taking the practice test trying to figure out the answer. Barrons DAT is full of mistakes and thank god im just using it for extra practice problems and not my main source

 

[ForeverKhaled]

thanks guys, I really appreciate it. I was going crazy when I was taking the practice test trying to figure out the answer. Barrons DAT is full of mistakes and thank god im just using it for extra practice problems and not my main source

Its good to study from a book with mistakes. That's if you can point them out. =]

 

[Kobebucsfan]

if the answer choice C read S-2> Cl-> Ar> k +
instead of Cl+ then it would be correct


they r then all isoelectronic (same#electrons) so increasing atomic number smaller they get 👍👍👍👍👍👍

 

[AllahIsGreater]

People warn you to stay away from Barrons as its FULL of mistakes. If i were you i would only use it for its PAT sections.