Electron Orbital Calculator Applet

This applet calculates the electron shells of arbitrary elements in quantum number order, which turns out to disagree with experiment in 19 known cases for elements up to 104 (see below for a list). The source is right here [StuffIt] [tar] [zip], released under the GPL.

To use:

  1. Type the atomic number or symbol for an interesting element into the "Atomic Number:" box.
  2. Click "Shells!" to see the atomic data and electron configuration in good old "1s2 2s2 2p6 ..." format.
  3. If you want to see shells in shorthand notation (e.g., see Potassium as "[Ar] 4s1"), check the shorthand box and click "Shells!" again.

Known errors: Except for the errors noted here, elements 1 through 104 agree with the 76th Edition CRC Handbook of Chemistry and Physics, pg. 1-13. The applet does not take close energy levels into account, and so calculates incorrect results for elements 24, 29, 41-42, 44-47, 57-58, 64, 78-79, 89-93, and 96. Elements higher than 104 have not been checked for accuracy; further errors in the transition elements in the d block and above seem very likely. I am working to remedy this by including the real energy level calculations in the applet, rather than special casing the elements that don't fit the usual order.


The odds of this working increase substantially if you enable Java. Applet requires Java 1.1 or later.

The text displayed in the orbital field is pretty straight forward, but some "creativity" was required for displaying as yet nonexistent elements and orbitals. For example, turn on shorthand notation, and try entering element 300 in the Atomic Number Box. You will notice that the shell configuration is listed as:

[?-290] 11s2 7[L=5]8

What are the [?-290], and the 7[L=5]8 all about? Glad you asked. [?-290] is a stand-in for element 290's atomic symbol. It will be a noble gas when it is discovered, but for now, it has no name, so we have to make something up. The [L=5] is the representation of the orbital after f, which has also not been discovered or named yet (actually, it is commonly called "g" as it turns out, but I think that's cheating). When it is discovered, it will have the quantum angular momentum number (l=5). I know I should have used a lower case "l" (ell) instead of an upper case "L", but most fonts make that look as if I'm claiming that one is equal to five, which even I don't believe any more.

You will get a Java exception (nothing bad should happen to your broswer or applet viewer, but you will see a big, ugly error message in your Java console) if you ask for an element that is just beyond the modest plans of this applet (an atomic number of about 461 is about as high as this bothers to go, though it could be made to go arbitrarily higher by changing the OrbitalTextApplet.bigBang() method to calculate up to principal quantum numbers (n) larger than 6.

You'll also get a mostly harmless exception message if you ask for element zero (just as there is no pink in chemistry, there is no element zero in this applet, or in real life). Asking for negative atomic numbers is just silly, and will return silly results.


ElementPredicted (wrong)Actual (right)Difference
24... 4s2 3d4... 4s1 3d54s -> 3d
-
29... 4s2 3d9... 4s1 3d104s -> 3d
-
41... 5s2 4d3... 5s1 4d45s -> 4d
42... 5s2 4d4... 5s1 4d55s -> 4d
-
44... 5s2 4d6... 5s1 4d75s -> 4d
45... 5s2 4d7... 5s1 4d85s -> 4d
46... 5s2 4d8... 5s0 4d105s -> 4d (twice)
47... 5s2 4d9... 5s1 4d105s -> 4d
-
57... 6s2 4f1... 6s2 4f0 5d14f -> 5d
58... 6s2 4f2... 6s2 4f1 5d14f -> 5d
-
64... 6s2 4f8... 6s2 4f7 5d14f -> 5d
-
78... 6s2 4f14 5d8... 6s1 4f14 5d96s -> 5d
79... 6s2 4f14 5d9... 6s1 4f14 5d106s -> 5d
-
89... 7s2 5f1... 7s2 5f0 6d15f -> 6d
90... 7s2 5f2... 7s2 5f0 6d25f -> 6d (twice)
91... 7s2 5f3... 7s2 5f2 6d15f -> 6d
92... 7s2 5f4... 7s2 5f3 6d15f -> 6d
93... 7s2 5f5... 7s2 5f4 6d15f -> 6d
-
96... 7s2 5f8... 7s2 5f4 6d15f -> 6d

There is room for improvement in practically every aspect of the user interface, but here are a few of the more obvious ideas:

... and some equally obvious but less likely ideas:

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