Trend Exceptions

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Trend Exceptions

Postby bonnie_schmitz_1F » Sun Nov 04, 2018 4:13 pm

In my discussion, we saw how Be has a larger ionization energy than B even though B is farther to the right than Be because B has 1 electron in the 2p-orbital while Be has a full 2s-orbital. The same was true for N having a larger ionization energy than O because of its half full 2p-orbital. How do these exceptions in trends relate to electronegativity and electron affinity? are there any other exceptions to trends in electronegativity or electron affinity?

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Re: Trend Exceptions

Postby Chem_Mod » Sun Nov 04, 2018 8:04 pm

You can use the same logic for finding exceptions I. Electron affinity. But there aren't exceptions for electronegativity because it is a calculated, rather than measured (empirical) value.

Neil Hsu 2A
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Re: Trend Exceptions

Postby Neil Hsu 2A » Thu Nov 08, 2018 1:20 pm

Expanding off of the previous answer, an exception for electron affinity is that the electron affinity of carbon is higher than that of nitrogen. This is because the addition of an electron to carbon makes the shell half-filled, which is much more favorable compared to nitrogen having an electron added to its half-filled shell. This exception follows the same logic as the ionization energy one.

Bingcui Guo
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Re: Trend Exceptions

Postby Bingcui Guo » Thu Nov 08, 2018 7:38 pm

When the element has full orbital or half full orbital structure, their structure is so stable that it is difficult for them to lose electrons, which means that it would require more energy to move one electron away from them, thus making their ionization energy higher.

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Re: Trend Exceptions

Postby haleyervin7 » Thu Nov 08, 2018 7:47 pm

When looking at trends, what makes more of a difference, whether an element is further to the left or right or does up and down matter more?

Chloe Qiao 4C
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Re: Trend Exceptions

Postby Chloe Qiao 4C » Fri Nov 09, 2018 12:14 pm

I believe for atomic radius, the element going up and down matters more because when you go down a group, there are additional shells added. For ionization energy and electron affinity, there are less obvious trends.

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