Hydrogen is an unusual element because it behaves in some
ways l...

Question

Hydrogen is an unusual element because it behaves in some 
ways like the alkali metal elements and in other ways like 
nonmetals. Its properties can be explained in part by its electron 
configuration and by the values for its ionization energy 
and electron affinity. (a) Explain why the electron affinity of 
hydrogen is much closer to the values for the alkali elements 
than for the halogens.

Accepted Answer

hey everyone in this example, we're told that electron affinity is the energy change from the addition of one electron to a gaseous element or ion. We're told that the trend for electron affinity increases from left to right and increases down a period in the periodic table. However, nitrogen is unusual because it breaks this trend because it has the electron affinity of zero. And we need to explain why this is the case for nitrogen. So we want to recall that because electron affinity deals with the ease for which an atom will add or gain an electron. We need to determine how easy it is for nitrogen to accept an extra electron. And we want to recall the fact that elements or elements with stable and symmetrical orbital's are less likely to accept an electron. So what we would recognize is that in our S sub levels or for R. S orbital's we should say they're going to be most stable when fully filled when it comes to our P and D orbital's they're going to be most stable when half filled or totally filled with electrons. So we want to go ahead and look at the configuration of nitrogen and for nitrogen configuration we're going to use the shorthand version. So we would begin with the noble gas that comes before period two where nitrogen is located at on our periodic tables and that's going to be helium. So we place that in brackets, we're going to begin with our lowest energy sub level. And we should recall that because nitrogen is on period two. That would be the two S sublevel which we recall has only one orbital that can hold a maximum of two electrons. So we're going to fully fill in our s sublevel. So we have a stable and symmetrical S sublevel which is good moving on to our P sub level which also would begin at the second energy level. Since nitrogen is located on the period two of our periodic tables, we would have the two piece sub level in which we would count for three units in the P P sublevel of our periodic tables in order to land on our adam nitrogen. So that means we would fill in a total of three electrons. And we would recall that R p sublevel has a total of three orbital's and can hold a maximum of six electrons. So we would fill in those three electrons by recalling our poly exclusion principle and Hunt's rule where we would fill the electrons in as follows. And as you can see, we have three unpaid electrons but we do have a half. We do have half filled p orbital's. And because we have half filled p orbital, we can say therefore we have stable and symmetrical p orbital's And so because we have stable and symmetrical pew orbital's for the configuration of nitrogen, we would say that therefore nitrogen is less likely to accept an extra electron and that is due to the fact that we have half filled p orbital's in the configuration of nitrogen. So this is going to be our final answer this explanation here to complete this example. So I hope that everything I went through is clear. If you have any questions, please leave them down below. Otherwise, I will see everyone in the next practice video.

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