Chemistry · Chapter 6

Orbital Diagrams, Pauli and Hund

Pick a spin, then press a box to drop that electron in. The model checks Pauli and Hund after every press, counts the unpaired spins, and tells you what a magnet would do.

Your diagram press a box to add an electron

Pick a spin on the right, then press a box. One box is one orbital, and one arrow is one electron.

The same diagram on an energy axis lowest at the bottom

What a magnet would do unpaired spins decide

More unpaired spins mean a stronger pull. With every electron paired the sample is pushed away very weakly instead.

Nitrogen · N · 7 electronsPlace the valence electrons. The core is already filled for you.
Which spin are you placing?
Pick an element

The two rules

Pauli holdsNo box has two arrows pointing the same way.
Hund holdsNo box is doubled up while a box beside it is empty.
Count matchesYou have placed every electron this atom carries.

Live count

Placed
0
Still to place
5
Unpaired electrons
0
Magnet test
nothing yet
Configuration your boxes spell
—
The measured ground state
—
What to notice
Spread out before you pair

Two electrons in one box repel each other. Keeping them in separate boxes with matching spins costs less energy, so nature does that first.