Maximum Number of Electrons in Third Shell

[mellowmorgan]

I had an exam a couple days ago asking for maximum number of electrons in the third shell of an atom. The correct answer was 8, but I keep seeing all over the internet that it's 18. I also saw on the internet that elements like uranium and radon have 18 electrons in their third shells. Our textbook, however, does say that the max is 8. I asked my professor about it and he basically just looked at me like I was crazy and was really adamant about it being 8. Please help. I feel really confused at this point...

[dmaiski]

number of electrons in a shell can be denoted as 2n^2

so 2*3^2=18

 

also there are s, p, d, and f sub shells holding 2, 6, 10, and 14 , electrons respectively

 

also outer shells like to have electrons in them so the shell config of lets say hafnium is 2,8,18,32,10,2 instead of 2,8,18,32,12 as you would expect

in this case the s, and p subshell of shell 5 filled up and the s subshell of shell 6 formed

 

if you get to really big atoms fun stuff like 2,8,18,32,18,8,2 can happen (i love radium its symmetrical)

 

Edited September 26, 2012 by dmaiski

[mellowmorgan]

number of electrons in a shell can be denoted as 2n^2

so 2*3^2=18

 

also there are s, p, d, and f sub shells holding 2, 6, 10, and 14 , electrons respectively

 

also outer shells like to have electrons in them so the shell config of lets say hafnium is 2,8,18,32,10,2 instead of 2,8,18,32,12 as you would expect

in this case the s, and p subshell of shell 5 filled up and the s subshell of shell 6 formed

 

if you get to really big atoms fun stuff like 2,8,18,32,18,8,2 can happen (i love radium its symmetrical)

 

 

Thanks so much for your reply. Would you happen to know why my biology professor thinks it's 8?

[dmaiski]

Thanks so much for your reply. Would you happen to know why my biology professor thinks it's 8?

 

well atoms do try to keep 8 electrons in their outer shell, also he may have been talking about argon specifically, or limiting the explanation to the third row only.

ie. he may have been keeping it simple, though I don’t see why...

 

 

 

 

 

[mfa5]

From my very basic understanding the question seems to relate to the baisc concept of shell content; the responses sem to indicate that (as is frequently the case) there is more to things than the basic. if so an elaboration of the "space between" explanations, not shells, would be very helpful please!

 

 

[dmaiski]

the fun of physics....

 

basic concept: electrons(e- from now on) can behave as both particles and waves

 

a e- shell in an atom is actually a field where the e- are contained

 

when an e- moves from a shell it behaves more like a wave then a particle and dose not physically move through the empty space(its just in one place then it is in another)

 

http://upload.wikimedia.org/wikipedia/commons/1/11/Electron_orbitals.svg

 

an image of what the shells look like(roughly), each blob represents a sub shell.

 

I would suggest wikipedia for more basic info on this, my knowledge isn’t much deeper hen this