Electron Configuration Confusion
Posted: Sun Oct 09, 2016 6:44 pm
According to the Aufbau Principle, electrons fill up lower energy orbitals first. For example the electrons fill the 4s orbital then the 3d orbital since the 3d orbital has more energy than the 4s orbital. However, the course reader says that after the 4s orbital state/orbital occupies and electrons enter 3d state, then 3d state is lower in energy than 4s. Why does the 3p orbital have less energy after the 4s orbital is filled?