ionization energy question

[afatasstank]

hello,
which of the following elements has the highest second ionization energy? Cl, Ar, K, Ca. Supposedly the answer is K because it'll have noble gas-like valence electrons after losing its first electron so the second IE will be really high. However, as a general rule etc> I3>I2> I1, and since Ar already is noble gas to begin with, its I1 will be really high, which means its I2 will be even higher, therefore im like dah fauk, it could be higher than the K I2? plz consider this, and thanks in advance

Edit: also IE increases as you move up periods, which is another reason i feel Ar would be a better candidate.

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[sciencebooks]

hello,
which of the following elements has the highest second ionization energy? Cl, Ar, K, Ca. Supposedly the answer is K because it'll have noble gas-like valence electrons after losing its first electron so the second IE will be really high. However, as a general rule etc> I3>I2> I1, and since Ar already is noble gas to begin with, its I1 will be really high, which means its I2 will be even higher, therefore im like dah fauk, it could be higher than the K I2? plz consider this, and thanks in advance

Edit: also IE increases as you move up periods, which is another reason i feel Ar would be a better candidate.

Hm, based on the explanation, I think it's that in the first set, K is ionized to gain a stable octet while Ar is ionized to lose this stable octet. The "noble gas" configuration is always the most stable and always hardest to break.

 

[Singhp03]

hello,
which of the following elements has the highest second ionization energy? Cl, Ar, K, Ca. Supposedly the answer is K because it'll have noble gas-like valence electrons after losing its first electron so the second IE will be really high. However, as a general rule etc> I3>I2> I1, and since Ar already is noble gas to begin with, its I1 will be really high, which means its I2 will be even higher, therefore im like dah fauk, it could be higher than the K I2? plz consider this, and thanks in advance

Edit: also IE increases as you move up periods, which is another reason i feel Ar would be a better candidate.

K would have crazy Zeff(effective nuclear charge) on electrons not in its outer shell, thus it would be realllllly hard to take it out. It would be harder to remove 2nd electron from K as oppose to Ca bc the electron ur removiing would not be in the outer layer, like it is for Ca(Ca+2)

edit: IE trend is only good for 1st electron and generally for outer electrons, for the second and non outer layer electrons, number of protons matter!

 

[shaboobly]

the 1st IE of K is relatively low because it wants to become like a noble gas. the second one will be somewhat higher.

the 1st IE of Ar will have a higher energy than the 1st IE of K which in turn, based on logic, it would seem the second IE of Ar would have a higher energy than the 2nd IE of K.

 

[LoLCareerGoals]

hello,
which of the following elements has the highest second ionization energy? Cl, Ar, K, Ca. Supposedly the answer is K because it'll have noble gas-like valence electrons after losing its first electron so the second IE will be really high. However, as a general rule etc> I3>I2> I1, and since Ar already is noble gas to begin with, its I1 will be really high, which means its I2 will be even higher, therefore im like dah fauk, it could be higher than the K I2? plz consider this, and thanks in advance

Edit: also IE increases as you move up periods, which is another reason i feel Ar would be a better candidate.

I think I understand your confusion. It is really easy to start thinking about and misinterpret this question as which has the highest (I1+I2). But that is not what the question is asking! It doesn't matter how big of I1 we had to overcome, we pulled 1 el-on, now which one of these already ionized ions will be the most resistant to ionization?
The answer is the one with noble gas configuration as it has been said.
Careful with the periods trend, IE does not change as quickly there as it does moving left to right.

 

[shaboobly]

I think I understand your confusion. It is really easy to start thinking about and misinterpret this question as which has the highest (I1+I2). But that is not what the question is asking! It doesn't matter how big of I1 we had to overcome, we pulled 1 el-on, now which one of these already ionized ions will be the most resistant to ionization?
The answer is the one with noble gas configuration as it has been said.
Careful with the periods trend, IE does not change as quickly there as it does moving left to right.

i think you mean up and down within a group because groups are vertical and periods are horizontal. looks like you are comparing a period vs a period

as you move from left to right within a period, the radius becomes smaller, there is a higher Zeff and so the electrons are bound more tightly which means IE also increases across a period.

 

[TieuBachHo]

hello,
which of the following elements has the highest second ionization energy? Cl, Ar, K, Ca. Supposedly the answer is K because it'll have noble gas-like valence electrons after losing its first electron so the second IE will be really high. However, as a general rule etc> I3>I2> I1, and since Ar already is noble gas to begin with, its I1 will be really high, which means its I2 will be even higher, therefore im like dah fauk, it could be higher than the K I2? plz consider this, and thanks in advance

Edit: also IE increases as you move up periods, which is another reason i feel Ar would be a better candidate.

This is just my personal take. If you can give us the book's explanation, it'll be much easier.
K(19) = ... 3P^6, 4S^1.
Ar(18) = ... 3S^2, 3P^6.
Now, the second ionization of K falls into the 3P orbitals as well as Ar. However, K(19) has 1 more proton that would make it harder to give up an e-. Therefore, K second ionization energy would be higher than Ar.
The first and second ionization if Ar would be almost the same since they fall into the same energy-orbitals. However, the first and second ionization energy of K greatly differs.