Catalonia PAU Chemistry Practice Questions - Catalonia PAU Chemistry Examination - CIC Generalitat De Catalunya (Química 2n Batxillerat 2026) Exam

Atomic radius increases because additional electrons increase electron-electron repulsion. Atomic radius remains constant because electrons are added to the same principal shell n = 3. Atomic radius decreases because increasing nuclear charge increases effective nuclear charge (Zeff), pulling valence shell electrons closer. Atomic radius decreases initially then increases sharp at Phosphorus due to subshell half-filling.