3.33 and ionization energy

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Zuri Smith 1A
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Joined: Fri Apr 06, 2018 11:05 am

3.33 and ionization energy

Postby Zuri Smith 1A » Sun May 20, 2018 2:57 pm

I thought that:
a) ionization energy increases across a period and up a group, and
b) The element with the highest ionization energy is chosen as the central atom when creating a lewis structure.

Question 3.33 part b asks us to write the lewis structure of COCl2. I thought that O or even Cl had higher ionization energies than C, but the correct lewis structure depicts C as being the central atom. Why is that?

Part C left me similarly puzzled, with N being chosen as the central atom when F has a higher ionization energy than both N and O. Why is this the case?

Mario Reyes 1C
Posts: 45
Joined: Fri Apr 06, 2018 11:04 am

Re: 3.33 and ionization energy

Postby Mario Reyes 1C » Sun May 20, 2018 4:06 pm

We actually choose the atom with the lowest ionization energy for the central atom. Even with that, part c) is still confusing since O has a lower ionization energy than N does. Anybody understand why?

Zuri Smith 1A
Posts: 34
Joined: Fri Apr 06, 2018 11:05 am

Re: 3.33 and ionization energy

Postby Zuri Smith 1A » Mon May 21, 2018 9:35 pm

According to pg. 78 in the textbook, "In simple chemical formulas, the central atom is often written first, follow by the atoms attached to it." Perhaps this is the reason why the correct answer is what it was.

Bianca Nguyen 1B
Posts: 36
Joined: Fri Apr 06, 2018 11:04 am

Re: 3.33 and ionization energy

Postby Bianca Nguyen 1B » Mon May 21, 2018 10:22 pm

O may have a lower ionization energy than N, but it has a higher electronegativity than N, thus making N the central atom as it is the least electronegative. In the beginning of Chapter 3, the book said that we would say the atom with the “lowest ionization energy” is the center atom, but later on in the chapter, it says to use “lowest electronegativity” instead. The trends for both are almost the same but with slight differences, as seen in this problem.


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