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Chemistry Forums for Students => High School Chemistry Forum => Chemistry Olympiad and other competitions => Topic started by: sn1sn2e1e2 on March 25, 2014, 09:47:40 PM

Title: Electron Affinity Series
Post by: sn1sn2e1e2 on March 25, 2014, 09:47:40 PM
Which process RELEASES the most energy?

(A) Mg2+ (g) + e-  :rarrow:  Mg2+(g)
(B) Mg+(g) + e-  :rarrow: Mg(g)
(C) Na2+(g) +e-  :rarrow: Na+(g)
(D) Na+(g) +e-  :rarrow: Na(g)

I chose C because...

Electron Affinity= E(initial) minus E(final) and since Na2+ is highly unstable (so high in energy) and Na+ (low in energy because favorable configuration)= large, position energy release

Can you check if my explanation is correct? ^^^
Title: Re: Electron Affinity Series
Post by: Rutherford on March 26, 2014, 12:17:27 PM
I would choose C, too.
Title: Re: Electron Affinity Series
Post by: mjc123 on March 27, 2014, 09:34:15 AM
I agree with C, but saying "Na2+ is higher energy than Na+" is not really an explanation, more a restatement of the question. Why is it higher?
Perhaps it is easier (I find it so) to turn the question round and ask which of the following ionisation processes requires most energy input:
Mg+  :rarrow: Mg2+ + e
Mg  :rarrow: Mg+ + e
Na +  :rarrow: Na2+ + e
Na  :rarrow: Na+ + e
Ask yourself: which electron is being removed in each case?