Exceptions in the trends

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Nuoya Jiang
Posts: 84
Joined: Sat Sep 14, 2019 12:17 am

Exceptions in the trends

Postby Nuoya Jiang » Sun Oct 27, 2019 1:00 pm

Hi, what are some examples of exceptions in the periodic trends, such as the radii of oxygen and nitrogen do not fit the trend?

Ethan Lam 4A
Posts: 69
Joined: Thu Jul 11, 2019 12:17 am

Re: Exceptions in the trends

Postby Ethan Lam 4A » Sun Oct 27, 2019 2:38 pm

Exceptions to the periodic trends are due to that specific atom's electron configuration and Hund's rule. For example, the first ionization energy of Boron is less than that of Beryllium.

Aliya Jain 2B
Posts: 86
Joined: Wed Sep 11, 2019 12:16 am

Re: Exceptions in the trends

Postby Aliya Jain 2B » Sun Oct 27, 2019 3:01 pm

Another example is that nitrogen's electron affinity is lower than carbon's and that Neon's is not only lower than fluorine's, but is actually lower than lithium's.These exceptions are also due to electron configurations!

Ashley R 1A
Posts: 41
Joined: Sat Aug 24, 2019 12:16 am

Re: Exceptions in the trends

Postby Ashley R 1A » Sun Oct 27, 2019 3:58 pm

Another one is in ionization energy! Generally as you move across a period, the ionization energy should increase. However, the exception is that if there are e- in the same orbital, for atoms right next to each other on the periodic table, it would be easier to remove e- in the same orbital because electrons don't like to share orbitals. If in different orbitals it may be more difficult to remove e- even if elements are in the increasing order across the period.

Amanda Ung 4D
Posts: 50
Joined: Thu Jul 25, 2019 12:17 am

Re: Exceptions in the trends

Postby Amanda Ung 4D » Sun Oct 27, 2019 9:38 pm

This isn't a trend but I think a good exceptions to remember when doing electron configuration are chromium, copper, molybdenum and silver such that a half or full d orbital is more stable than being partially filled, so an electron from the 4s/5s orbitals rise to a 3d/4d orbital.

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