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Topic: Xenon, Radon & Ununoctium - odd electron arrangements  (Read 3222 times)

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Offline memoguy

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Xenon, Radon & Ununoctium - odd electron arrangements
« on: July 21, 2012, 10:08:24 PM »
I have just started chem at school and have a couple of questions for the bright minds over here on the forums.

With the Nobel gasses, continually i see on the internet that the reason they are inert is due to the outer shell being full. But i don't see how this is true. I was taught that the shells have the following maximum capacities:

So Helium & Neon are both at maximum capacity (with 2 and 2,8) but argon, Krypton, Xenon, Radon and Ununoctium are all not. They all have 8 electrons on the outer shell but these shells are above the second energy level maximum. Hmm, i don't think i articulated that very well. Let me try again:

if the maximums are:

makes sense

makes sense

WOW! Why is the final layer an 8? For the outer layer to be at max capacity should it not be 18?

WOW! Why is the final layer an 8? For the outer layer to be at max capacity should it not be 32?

so i think you get my point there. Where is the final layer less than the maximum capacity despite a bunch of resources saying that Nobel gasses are inert due to the outer layer being at maximum capacity.


I was told that the electrons flow on from layer to layer. So if there was 10 electrons then layer 1 fills to two, layer 2 fills to 8. That makes sense for Helium, Neon, Argon & Krypton. But then we get to Xenon where the shells go:
2,8,18, 18, 8

WOW! Why didn't layer 4 fill to 32 rather than 18, so the electron arrangement would be:

This confusion applies to Xenon, Radon and Ununoctium!

I thought i was getting the hang of chem but now it seems that these elements simply break the laws!

I would be so pleased if someone could give me a hand here.

Offline Dan

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Re: Xenon, Radon & Ununoctium - odd electron arrangements
« Reply #1 on: July 22, 2012, 03:06:53 AM »
You are using a highly simplified model for electronic structure, which is why it's not working. You will have to read about s, p, d, anf f subshells to understand the order of filling.

Read around the subjects of electronic configuration and the aufbau principle. For example:
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