# 658: Orbitals

 Orbitals Title text: Except the people filtering in late are the partiers, so you end up with drunken makeouts in the living room and the next roommate to return home has to sleep in the hall lounge orbital.

## Explanation

When determining where to place electrons in an atoms, three rules are generally used: the Pauli exclusion principle, the Aufbau principle, and Hund's rule. The Pauli exclusion principle, from which the pun is derived, states that no two electrons (or indeed any fermion) can occupy the same atomic state. Therefore, an electron orbital is limited to two electrons: one with a 1/2 spin, and the other with a -1/2 spin. The Aufbau principle states that lower energy orbitals are occupied previous to high energy orbitals. Hund's rule states that electrons will try to fill orbitals individually, and only pair up when every orbital has a lone electron in it.

In the comic, electrons are being equated to people, and rooms (or couches) are equated to orbitals. The reverse of Hund's rule is then followed: people will try to pair up in a room first, and only when all the couples have done so will rooms be allocated to single people. The Pauli exclusion principle here means that only two people can occupy a room at a time (should those people be romantically involved). The Aufbau principle therefore means that more restful rooms are filled previous to less restful rooms.

The title text jokes about drunken party-goers, who ignore the Pauli principle perhaps out of inebriation. They then end up partying and sleeping together with many people in the living room, leaving the roommate stuck in the third desirable location, the hall lounge.

## Transcript

[Cueball is holding up a pointer in front of a diagram of a dorm apartment. On the diagram, there are two connected pairs of dots in each bedroom, and one dot on the couch.]
Cueball: Thus, once all the dorm bedrooms are occupied by romantic pairs, additional roommates are forced into less restful "living room couch" orbitals.
The Pauli Sexclusion Principle

# Discussion

The explanation implies that the romantic pairs must be male-female. I do not see this restriction in the comic. 108.162.219.223,

When I finally came to college, this comic was always on my mind. Then came a rather... er... covalent night. Except I didn't actually form the second pair, but came really close to doing such. But even then this comic always came to mind. International Space Station (talk) 08:59, 8 October 2015 (UTC)