A New Periodic Table Helps TeachWe show how students of chemistry can easily write down the entire periodic table with a simple mnemonic. And using the diagonal orbital filling rule they can quickly construct the complete electronic structure of most atoms in their ground state. My periodic table was invented in the late 1960's to teach my sister Susanna, who subsequently aced her chemistry class. I have taught it to many others since, including my nephew Marc Doyle, who earned his Ph.D. in chemical engineering from UC Berkeley. When I taught it to Mike Jittlov in the mid-1990's, he made a beautiful drawing which subsequently was added to Mark Leach's Internet Database of Periodic Tables.
the Electronic Structure of Atoms
How to Pronounce the Periodic TableInspired by Sesame Street in the 1960's teaching children alphabetic order by pronouncing the alphabet (ab-cu-def-ki-jekul-mun-op-qur-stuv-wix-yz), we suggest that the atomic names can also be pronounced in their chemical order, giving us the atomic aide memoire. It's best to learn the pronunciation by hearing it, so please click on our under one-minute audio file, while following along the symbols in the periodic table above.
The Aufbauprinzip or Building-Up PrincipleThis principle says that in the ground (unexcited) state of an atom, its lowest energy electron shells (atomic orbitals) fill up before any higher levels are occupied. The "principal quantum number" n describes a "shell," and the "azimuthal quantum number" l describes subshells. The subshells are named s, p, d, and f for historical reasons. In an s subshell only two electrons are allowed by the Pauli Exclusion Principle (one "spin-up," the other "spin down"). In a p subshell, three values of the magnetic quantum number m (+1, 0, -1) multiplied by two spins allows up to six p electrons. In the d shell, 5 magnetic substates and in the f subshell 7 substates give us up to 10 d electrons and up to 14 f electrons. You can now determine the electron configuration for any ground state atom. Let's do potassium (K), the first element in the shell n = 4. It has only one 4s electron, and we can read off the inner shell electrons by following down the diagonal rule - 1s2 2s2 2p6 3s2 3p6 4s. Charles Janet first produced a diagram with a key to the electron structure. It was not arranged to show the diagonals of Madelung's rule. Janet was first to speculate that no element past atomic number 120 would be found. Here is an updated version.
ReferencesEric Scerri on the Madelung Rule Normal | Teacher | Scholar