Hund's Rule [ENDORSED]

[Anthony Stone 1K]

Can someone explain Hund's Rule? Im a bit confused by it

[KyLee 1H]

Hund's Rule states that orbitals in a sublevel must be singly occupied before doubling up. Also, these singly occupied orbitals must have electrons with the same spin (parallel).

[Aryan Singh 3F]

Yep, I agree with the previous poster. Hund's Rule states that each suborbital in an orbital must have one electron each before any suborbital is filled with two electrons. This is contrast to Pauli's Exclusion Principle which specifies that a suborbital can only hold 2 electrons max.

[Michael 1G]

Hund's rule basically states in every subshell, there must be at least one electron in each orbital before a previous orbital can have two electrons. For example in a 2px orbital there can only be one electron in it if there isn't at least one electron present in the 2py and 2pz orbitals first.

[Albert 1I]

Hund's rule states that electrons do not pair up in orbitals until they have to; for example in a 2p subshell there are 6 possible electrons (2 in each orbital). If there are 3 electrons in the said 2p subshell, they will each occupy an orbital rather than being in the same one.

[Shay Crookall 2L]

Everything that everyone has said above is great! Also want to add that it states that any electrons in singly-occupied orbitals are the same spin.

[Diya Kar]

Does the Pauli Exclusion criteria dictate that two electrons within an orbital must have opposite spins while Hund Rule's indicates that electrons must be unpaired in each orbital before they can be paired(parallel rule)?

[Anish_Marripati_2F]

Hund's Rule states that each orbital must be filled with one electron before it can have another electron of opposite spin.

[Uma Patil 2A]

Hunds rule states that each orbital in a subshell has one electron in it before one of the orbitals receives a second electron.

[Joanna Zhao 1J]

Every comment above mine is correct! I'd like to add that the reason why all orbitals in a subshell must be singly occupied before electrons start "pairing up" is because of electron-electron repulsion. Not to anthropomorphize electrons, but their negative charges repel each other so if there is still an empty orbital, the electron will go there before electrons start needing to pair up and share orbitals.

[Chem_Mod]

Hund’s rule has two main components to it

1. Every orbital in a sub level must be singly occupied, before any can be double occupied
-in simple terms, every orbital must have at least one electron in it, before any can have two
-see the electron configuration of oxygen, where every orbital in 2p has at least one electron in it, so it’s appropriate that one has two since all orbitals have at least 1 electron

2. In a sub level that has multiple singly occupied orbitals, they all must have the same spin
-so maximize total spin, all the electrons will have the same spin
-see the electron configuration of Nitrogen, all electrons in the 2p orbital are all facing upward and have the same spin

[SuryaDham 3E]

Hund's Rule basically states that every orbital in a sublevel is singly occupied before any orbital is doubly occupied and all of the electrons in singly occupied orbitals have the same spin (to maximize total spin).

[Aaron Kwan 3B]

does Hund's rule mention anything about the maximum number of electrons in an orbital?

[Nishan Reddy 3K]

It essentially states that each orbital of a certain type (s, p, d, f) must filled with one electron (with parallel spins) before each orbital could be filled with a second.

[Caitlyn Lo 2F]

Hund's Rule states that each orbital must be filled with an individual electron before pairs of electrons can be in the same orbital at opposite spins.

[Nicola Higgins 14B]

Does anyone have an acronym or pneumonic for memorizing the different rules and what they mean? I have trouble with Hund's, The Pauli Exclusion Principle, and the Aufbau Principle.