Maximum Atomic Shells
How many shells are available for an atom to use up?
This depends upon how you want to define "shells". If you mean only the
primary quantum number (n) only, and not the sub-shells, usually labeled
as (s,p,d,f,g,...), nor the sub-sub-shells caused by electron-electron
spin interactions, and sub-sub-sub shells caused by electron-nuclear spin
piled on top of all the other sub shells, and other corrections for finite
electron mass, and corrections for relativity, then the energy of the
shells goes like E = R*[1-1/n^2] for the simplest atom, hydrogen. Then,
after all those provisions, the observation of the "excited" electron
(let's assume a single electron from the H atom) is smeared out by a
number of effects: 1. Doppler broadening -- that is the difference in
frequency that occurs as a result of the particular H atom moving toward
or away from the detector, 2.Pressure broadening that comes from three
sources -- A. that is due to collisions between emitting atoms and the
particles surrounding it; Van der Waals broadening that is due to induced
broadening of an electronic state resulting from an induced dipole. 3.
Stark broadening that results from complex interactions (too messy to
I am not intending to "over answer" your question to just throw up a
bunch of technicalities in your face to avoid a simple answer, but your
inquiry really opens up a lot of very involved effects and it would be
intellectually dishonest to sweep them "under the rug". Your question is
very basic and deserves a full answer, even though analyzing the effects in
detail is quite complicated.
You can find the known energy levels of many elements at the website:
There is a whole field of atomic spectroscopy devoted to the study of the
spectra of where the outer electron is in an energy state "close to being"
an ion. Those are called Rydberg states and behave "almost" like single
electron atoms with a nucleus having a charge of the atomic number, (Z-1).
To repeat, your question is very valid, but I don't think there is a
"simple" answer. You can also find a summary of the answer to you inquiry in
the American Institute of Physics (AIP) Desk Reference under "Atomic
There are 7 shells (energy levels) available.
Hvae you ever seen an Aufbau filling diagram?
It looks like this:
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
So, let's say you wanted to write the electron
configuration for Sulphur. From the periodic table, we
know sulphur's atomic number is 16--which means it
hass 16 electrons and 16 protons.
Now, using the table, we're going to write the
We start from the bottom left of the table (1s) and
then go up on diagonal lines from the right corner to
For example, for S-16 (the number is () is the number
of electrons that can go in each orbital):
Here's one more example. Fe-26
Using this table, you can easily write the electron
configurations for any element! Including the really
So, if you write out the configuration for the last
element on the periodic table, you can...and you'll
see the highest number orbital you get to is 7.
Hope this helps.
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Update: June 2012