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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: th3plan on July 30, 2007, 08:19:34 PM

Title: Electron and shell configuration problem
Post by: th3plan on July 30, 2007, 08:19:34 PM

ok guys i have a problem, im trying to review for a chemistry placement test and i dont understand why lets say u get to K (pottassium) 4s^1.  Why isnt it instead 3d^1 3p^6.  But instead it skips D and then goes to 4s^1.  Why??? :S im so confused

Title: Re: Electron and shell configuration problem
Post by: Yggdrasil on July 30, 2007, 09:30:32 PM

The 4s orbital is lower in energy than the 3d orbitals.

http://en.wikipedia.org/wiki/Aufbau_Principle

Title: Re: Electron and shell configuration problem
Post by: th3plan on July 30, 2007, 09:43:18 PM

Yggdrasil just to be sure S = 2 P= 6 D=10 F=14?  Thats the most they can hold if im correct ?  And one more thing , so like 5s is smaller then 4f and 6s is smaller then 5f if i understand your explanation right ?

Title: Re: Electron and shell configuration problem
Post by: th3plan on July 30, 2007, 10:05:12 PM

also why is Ge  written as 3d^10 4s^2 4p^2.  But instead not like 4s^2 4p^2.  some they write others they dont , what is the logic behind it >?


Thanks

Title: Re: Electron and shell configuration problem
Post by: enahs on July 30, 2007, 10:13:53 PM

http://www.physchem.co.za/Atomic/Electron%20Configuration.htm
http://www.fordhamprep.org/gcurran/sho/sho/lessons/lesson36.htm
http://library.thinkquest.org/10429/low/eleconfig/electron.htm



More practice:
http://preparatorychemistry.com/complete_electron_configuration_tutorial.htm

Title: Re: Electron and shell configuration problem
Post by: Yggdrasil on July 31, 2007, 02:35:49 PM

For atoms in the 4th period, the 3d electrons count as valence electrons.  Similarly, for atoms in the 5th period, 4d electrons count as valence electrons.  In general, electrons in the (n-1)d and (n-2)f orbitals count as valence electrons and should be shown on the electron configuration.