Home Page
About
Chemogenesis Web Book
Chemical Thesaurus
Tutorials and Drills
Shop
Reviews
Contact
Links
Frequently Asked Questions

pre 1900 formulations
1900 to 1949 formulations
1950 to 1999 formulations
2000 to 2009 formulations
Spiral formulations
3 dimensional formulations
Data mapping periodic tables
Miscellaneous periodic tables
Books and reviews
non-chemistry periodic tables
All periodic tables


The INTERNET
Database of Periodic Tables

There are hundreds of periodic tables in web space, but there is only one comprehensive database of periodic tables & periodic system formulations. If you know of an interesting periodic table that is missing, please contact the database curator: Dr Mark R Leach.

pre 1900 formulations 1900 to 1949 formulations 1950 to 1999 formulations 2000 to 2009 formulations Spiral formulations 3 dimensional formulations
Data mapping periodic tables Miscellaneous periodic tables Books and reviews non-chemistry periodic tables All periodic tables


1936

Orbital Filling With Electrons

Students of chemistry are often confused why the orbitals fill with electrons: 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p6... etc., because the 3d10 seems to be 'out of sequence'.

This 'out of sequence' difficulity is nicely explained if the orbitals are arranged in a slightly different way:

The aufbau principle states that in the ground state of an atom or ion, electrons fill atomic orbitals of the lowest available energy levels before occupying higher levels. For example, the 1s shell is filled before the 2s subshell is occupied. In this way, the electrons of an atom or ion form the most stable electron configuration possible.

The order in which these orbitals are filled is given by the n + rule, also known as the Madelung rule (after Erwin Madelung), the Janet rule or the diagonal rule.

Orbitals with a lower n + value are filled before those with higher n + values. In this context, n represents the principal quantum number and ? the azimuthal quantum number. The values = 0, 1, 2, 3 correspond to the s, p, d and f orbital lables.

Julio Gutiérrez Samanez writes:

"I send you the diagram below that reconciles quantum mechanics (diagram for filling the electronic cells) with the Janet table or LSPT. Explaining the duplication of periods with the duplication of the quantum number n, and the introduction of Tao (T) spin of the level or spin of the period, which explains the parity of the symmetric periods."

Top of Page


pre 1900 formulations 1900 to 1949 formulations 1950 to 1999 formulations 2000 to 2009 formulations Spiral formulations 3 dimensional formulations
Data mapping periodic tables Miscellaneous periodic tables Books and reviews non-chemistry periodic tables All periodic tables

Periodic Table, What is it showing?
Binary Compounds

© Mark R. Leach 1999-


Queries, Suggestions, Bugs, Errors, Typos...

If you have any:

Queries
Comments
Suggestions or periodic table representations not shown on this page
Suggestions for links
Bug, typo or grammatical error reports about this page,

please contact Mark R. Leach, the author, using mrl@meta-synthesis.com

This free, open access web book is an ongoing project and your input is appreciated.