Ciro Santilli @cirosantilli  40

Boring rule that says that less energetic atomic orbitals are filled first.

Much more interesting is actually determining that order, which the Madelung energy ordering rule is a reasonable approximation to.

Equation "Hydrogen spectral series mnemonic" gives for example from principal quantum number 1 to 2 a difference:which with Planck-Einstein relation gives about 121.6 nm ($2.47\times 10^{1}5$ Hz), which is a reasonable match with the value of 121.567... from the NIST Atomic Spectra Database.

Setups we've tried:

The first chapter of the New Testament.

The cheapest and most resilient way to publish text content humanity has achieved so far.

Some tests:

The heart/main innovation of GitHub!