Galicia PAU Chemistry Química 2o Bachillerato CIUG Practice Questions - Galicia PAU Chemistry Química 2o Bachillerato CIUG 2026 (Probas D'Acceso á Universidade) Exam

Phosphorus has a stable half-filled 3p³ subshell, whereas sulfur has paired electrons in one 3p orbital experiencing electron-electron repulsion. Sulfur has a smaller nuclear charge than phosphorus, resulting in weaker attraction for valence electrons. Phosphorus has a significantly smaller atomic radius than sulfur. Sulfur's valence electrons are shielded by an extra inner electron shell.