Elements that have large negative electron affinities generally h...

Question

Elements that have large negative electron affinities generally have (LO 6.10) 
(a) high values for Zeff and a vacancy in a valence orbital. 
(b) low values for Zeff and a vacancy in a valence orbital. 
(c) high values for Zeff and filled valence orbitals. 
(d) low values for Zeff and filled valence orbitals.

Accepted Answer

welcome back everyone. Elements with low ionization energies generally possess the following. So let's begin by referencing our periodic table. And we want to recall the trend for ionization energy which we would recognize increases as we go towards the top right of our periodic table because our answer choices also consider effective nuclear charge. We're going to recall the trend for effective nuclear charge where it also follows the same trend increasing towards the top right of our periodic table. And so considering elements with low ionization energies, we would go opposite to our trend which would be towards the bottom left of the periodic table as far as our elements that we would choose. And so we're going to see that corresponds again opposite to the trend of effective nuclear charge, meaning that are effective nuclear charge should be much lower in value. So let's already be able to rule out choices C. And D. Leaving us with choices and be to choose between which considers their valence orbital's as well either being filled or unfilled. So what we should think of is in general and chemistry things want to go towards the tendency of being stable. However, when we think of specifically in structures of molecules where we have to consider our octet rule or in the case of atoms like hydrogen, Our duet rule which we recall describes atoms which should have at least eight electrons for the octet rule around themselves or two electrons around themselves for the duet rule. And let's think of an atom like lithium for example which we should recognize is in group one a on the periodic table corresponding to one valence electron Where we see that it has in total based on its atomic # three electrons total. And so if we were to imagine the atom of lithium where around its nucleus we have our first sub level containing our core electrons which would be our first two electrons. And then around that first sub level we have a second sub level because lithium is across period two on the periodic table. So that would contain the valence electron being our only one valence electron here. We're going to see that because we just have the single valence electron here in its uttermost sublevel lithium is going to be highly reactive and generally unstable. Now we're calling the fact that ionization energy describes the energy to remove an electron from an atom. If we are to remove this electron from the valence shell, this valence level is going to collapse into this innermost sublevel here which would now make this our valence orbital containing just two electrons that are left. And this would honor our duet rule meaning that lithium would be more stable if we were to remove this outermost electron because it would want to be less reactive and so being more stable, it's going to be much harder to try to remove one of these two electrons here that are paired with one another. And so we would have a high ionization energy. And so because we are to remove this outermost electron from this valence shell that leaves this original valence show empty now. So we would rule out Choice B. And that would leave Choice A as the only correct choice where elements with low ionization energies will generally possess low effective nuclear charge values and unfilled valence orbital's. And again, these unfilled valence orbital's are a reference to the orbital being unstable, meaning the atom is overall going to be more reactive and much easier to remove electrons from hence the low ionization energy. So I hope that everything was clear. If you have any questions, please leave them down below and I'll see everyone in the next video.

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