Ciro Santilli @cirosantilli  40

That is, two electrons per atomic orbital, each with a different spin.

As shown at Schrödinger equation solution for the helium atom, they do repel each other, and that affects their measurable energy.

However, this energy is still lower than going up to the next orbital. TODO numbers.

Bibliography:

This changes however at higher orbitals, notably as approximately described by the aufbau principle.

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!