Aufbau vs Hund's

[rachel liu 3k]

I'm a little confused on the difference between the Aufbau Principle and Hund's Rule...don't they both pretty much mean you fill the lower energy levels first and then build your way up?

[DarrenKim_1H]

Hund's Rule directly states that other sub levels besides s, have electrons placed in individual orbitals before being paired.

In contrast, Aufbau's principle can be explained in three points
1. The number of electrons in an atom is equal to the atomic #
2. Each added electron will enter the orbitals in the order of increasing energy.
3. Any orbital cannot take more than 2 electrons.

[cassidysong 1K]

Hund's principle states that every orbital in a subshell will be occupied with one electron before any one orbital is doubly occupied. Whereas Aufbau's principle states that lower energy orbitals fill before higher energy orbitals so that orbitals in the n=1 energy level will fill before the n=2 energy level.