the.com/electron pairs
two electrons, same orbital, opposite spins, sharing a tiny apartment nobody else can enter.
means a pair of electrons occupying the same orbital in an atom or molecule, either bonding two atoms together or sitting alone as a lone pair.
from emerged from g.n. lewis's 1916 idea of the covalent bond, later justified by pauli's 1925 exclusion principle explaining why exactly two electrons, spinning oppositely, can share one orbital.
pauli mandateexclusion principle forbids more than two per orbital
vsepr logiclone pairs repel more, squeezing bond angles smaller
not always trueradicals and metals break the pairing rule constantly
for instance
water molecule — oxygen holds two lone pairs, bending h2o to 104.5 degrees
ammonia lone pair — nitrogen's spare pair makes nh3 a sharp base and ligand
cooper pairs — electron pairs in superconductors, but bound by phonons not orbitals
double bond ethylene — two shared pairs lock c2h4 flat and rigid