Dr.Collins chemistry question

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AntonFreeman

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Set 7 question 20

From what I understand electron affinity is defined as positive value if atom gaining an electron results an exothermic reaction. CL becoming CL- will result in highest electron affinity.

20. Why do elements sodium and chlorine bond so readily?
answer a. electron exchange caused by low ionization energy of sodium and low electron affinity of chlorine.

Is there a mistake in wording of the answer? I could see why it could say chlorine having the 'most negative value' of electron affinity, but the wording sounds kind of funny to me.

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They probably meant high electron affinity of Chlorine. The answer I'd give for why those two elements bond so readily is quite a bit more in depth than that though...
 
Set 7 question 20

From what I understand electron affinity is defined as positive value if atom gaining an electron results an exothermic reaction. CL becoming CL- will result in highest electron affinity.

20. Why do elements sodium and chlorine bond so readily?
answer a. electron exchange caused by low ionization energy of sodium and low electron affinity of chlorine.

Is there a mistake in wording of the answer? I could see why it could say chlorine having the 'most negative value' of electron affinity, but the wording sounds kind of funny to me.
actually i wondered about that too. i think i figured it out. Cl has a high electronegativity, meanig that it can accept an electron very easily. Electron affinity however, describes the energy released when something accepts an electron. Since Cl accepts an electron easily, that means it won't release much energy when doing so.Therefore, the answer is low electron affinity.

If it helps, you can think of ionization energy. The easier it is to remove an electron from an atom, the lower the ionization energy. The harder it is to remove an electron, the higher the energy. that's ;why nobel gases have the highest ionization energy. hope that helps!! :)
 
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actually i wondered about that too. i think i figured it out. Cl has a high electronegativity, meanig that it can accept an electron very easily. Electron affinity however, describes the energy released when something accepts an electron. Since Cl accepts an electron easily, that means it won't release much energy when doing so.Therefore, the answer is low electron affinity.

If it helps, you can think of ionization energy. The easier it is to remove an electron from an atom, the lower the ionization energy. The harder it is to remove an electron, the higher the energy. that's ;why nobel gases have the highest ionization energy. hope that helps!! :)

Seems logical, however, doesn't Chlorine have a high electron affinity?:confused:
---> http://en.wikipedia.org/wiki/Electron_affinity
 
Yes, Cl has a high EA, there are several errors in the pch's post.

The simple answer is that the packet probably has a misprint and meant to say the low IA of Na and the high EA of Cl.
thanks or point that out. so the answer should be c then?
 
I understood it to mean that since electron affinity is represented by a negative number, the greater the affinity the lower the actual number (i.e. -130 is greater in amount than -7, and also lower in number).

Its confusing when a test says "higher electron affinity" because you don't know if the test means "greater in number" or "higher in number"...
 
thanks or point that out. so the answer should be c then?

I don't have the packet, so I have no idea what the choices were for possible answers. I just know that the correct answer - in simple terms - would be:
because Na has a low IA and Cl has a high EA.

I understood it to mean that since electron affinity is represented by a negative number, the greater the affinity the lower the actual number (i.e. -130 is greater in amount than -7, and also lower in number).

Its confusing when a test says "higher electron affinity" because you don't know if the test means "greater in number" or "higher in number"...

Electron affinity is defined as the negative of the energy change when an atom in the gaseous state accepts an electron to form an anion.

So for example Cl is more stable with a -1 charge and has a lower energy as an anion. So the energy change is negative when Cl accepts an electron; therefore, it has a positive electron affinity.

EA values are usually expressed in kJ/mol values. EA values are also not one of those that you talk about in absolute values - so wrt EA -7 would be greater than -130.
 
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