Another sort of electron config. question

[Sammy1024]

54. Which of the following elements would have an electronic configuration of ns^(n-l)d^ due to half-filled stability?

A. Copper
B . Silicon
C . Manganese
D . Molybdenum

I picked C because it's literally 3d5 but the answer was D because it can take an electron from s and create a half-filled orbital. For half - filled stability does it have to be something 1 or 2 electrons away that can create a half-filled orbital?

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[sps27]

I don't think it has to be 1 or 2 electrons away........it can jump shells too.....like in this case of Molybdenum. But this is a silly+tricky question. It does not say that 's' is also half filled, clearly enough.

 

[Sammy1024]

So for half-filled stability it's just something that is half-filled, it doesn't have to form something half-filled?

 

[sps27]

So for half-filled stability it's just something that is half-filled, it doesn't have to form something half-filled?

1) It could be half filled to begin with like Manganese OR 2) for ex., Chromium with 24 electrons and if I start filling in then I should end up with (4s2, 3d4) but since there exist a possibility to make half filled 'd' orbital by shifting 1 electron from '4s' orbital over to '3d' orbital, it will 'form' that more energetically favored (less energy, more stable) over (4s2, 3d4), so the final configuration will be (3d5, 4s1) and not (3d4, 4s2). Another example of the same behavior like Chromium is Molybdenum; same deal. Start filling in the electrons and you should have (5s2, 4d4) but since we could have (5s1, 4d5), it will form that more stable and favorable configuration as opposed to (5s2, 4d4).