## Applications of Hund’s Rule and Pauli Exclusion Principle

Rohan Kubba Dis 4B
Posts: 50
Joined: Sat Aug 17, 2019 12:18 am

### Applications of Hund’s Rule and Pauli Exclusion Principle

Can someone please describe Hund’s Rule and the Pauli Exclusion Principle, and its direct correlation to how it helps us write e- configurations? I am confused on when each one is applicable and not.

Jessica Castellanos
Posts: 61
Joined: Sat Aug 24, 2019 12:17 am
Been upvoted: 1 time

### Re: Applications of Hund’s Rule and Pauli Exclusion Principle

Hund's Rule says that since electrons repel each other (because they're all negatively charged), electrons in the same sub shell occupy different orbitals with parallel spin to stay at it's lowest energy because the farther away the electrons can be without reaching a high energy is ideal. So when you write the electron configuration of Carbon instead of writing 2p^2 you can write 2px^1 2py^1 which specifies that there are two electrons in the 2p orbitals, specifically one in the 2px and one in the 2py orbital.

The Pauli Exclusion Principle states that if there are two electrons in the same sub shell and orbital, the electrons will have opposite spins because the electrons repel each other. An example for this one would be Helium because there would be two electrons in the 1s orbital and since they repel each other they would have opposite spins so you would write their spins as + or - 1/2. Hope this helps!

nickianel_4b
Posts: 50
Joined: Thu Jul 25, 2019 12:17 am

### Re: Applications of Hund’s Rule and Pauli Exclusion Principle

Pauli Exclusion Principle--no more than 2 electrons per orbital, and if they're in the same orbital they must have opposite spins
Hund's Rule--due to electron repulsion, electrons in the same subshell occupy different orbitals and with parallel spin
I'm not sure if they really help in writing electron configurations, I think these rules just describe an electron's probable behavior in an atom, so it's more conceptual.