Chemical Forums
Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: shefv on April 27, 2015, 03:24:35 PM
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Removing and electron required the most energy for which on of the following?
A. Na-
B. Na
C. Na+
D. Na2+
I am thinking of it like this
A. Na- = Mg
B. Na = Na
C. Na+ = Ne
D. Na2+ = F
So, since Ne is a noble gas, I thought that it would require the most energy to remove electrons. But the answer is supposed to be D. How?
I do know that F is highly electronegative but wouldn't noble gas configuration still require more energy than F?
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You are right - it is the Ne configuration that requires most energy to remove an electron. Na2+ will be the product of this ionization, so D is the correct answer.
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Na2+ gives a F configuration
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A simplistic explanation is that each electron you try to remove costs more energy, because the effective nuclear charge becomes greater. A crude analogy might be asking for money from a relative. For each dollar he gives you, the less likely he is to give you more. :)
Look at the tabulated ionization potentials listed on the wikipedia page. You will see that, regardless of the element, removing a second electron is always more difficult than removing a first. (And removing a third more difficult than removing a second, etc.)
http://en.wikipedia.org/wiki/Ionization_energy
Comparing ionization potentials of different elements is less straightforward, but generally boils down to the same kind of nuclear core charge argument.
The flaw in your argument is that Na2+ does not equal F and Na+ does not equal Ne. From an electron configuration standpoint, yes, but not from a nuclear core charge standpoint. If the question asked you to compare ionization potentials of these elements, you'd be correct. But it isn't, so you're not.