Electron configurations

An electron configuration is a sequence of orbital^occupancy pairs, each pair denoting an orbital label and the number of electrons in it.

Orbital labels

An orbital label is a digit-sequence (the principal quantum number) followed by a single letter from the set s p d f g h (the azimuthal quantum number, lowercase).

1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10

$\text{1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10}$

This is the ground-state configuration of zinc. The model captures it as ElectronConfiguration(orbitals: [["1s","2"], ["2s","2"], ...]).

Term symbols

A term symbol describes the total angular momentum state of an atom. The form is ^{multiplicity}L_{J} where L is a capital letter (S, P, D, F, …) and J is the total angular momentum quantum number.

Deferred to v2

Term symbols are first-class in the model (ElectronConfiguration::TermSymbol) but the v1 parser doesn’t promote them from text — write them inside an embedded-math escape for now. See embedded math.

Filled shells

A filled shell is implicit in the orbital list — no special syntax. The renderer emits each orbital as <msup><mi>orb</mi><mn>occ</mn></msup> joined by non-breaking spaces.

What’s not yet in v1

• Box notation (orbital diagrams with up/down arrows) — needs SVG.
• Hund’s rule validation — out of scope for the parser.
• Excited-state vs ground-state markers — needs syntax design.