Quantum Numbers and Electron Configuration

12-Pro Chemistry '24-'25 (made with AI assistance.)

Principal Quantum Number

n; n ≥ 1 - where each number represents an energy level
Responsible for overall size of the orbital

Azimuthal Quantum Number

l
Responsible for overall shape of orbital
Also known as the angular momentum number

Ranges from 0 to n - 1

Magnetic Quantum Number

Responsible for orientation of the orbital
Ranges from -l to +l, including 0

Spin Quantum Number

Responsible for the spin of the electron
Takes on a value of +1/2 or -1/2

Types of Orbital Shapes

s; where l = 0
p; where l = 1
d; where l = 2
f; where l = 3

Some mnemonics for Orbital shapes

1. s - Spherical
   p - Pretzel or Parang Dumbbell
   d - Double Pretzel or Dumbbell
   f - Fucked up (sir’s words)

2. The sign for the letter S in ASL is a closed fist, so using this each finger you put up corresponds to an orbital shape as per n values
   s=closed fist, p= 1 finger, d=2 fingers, f=3 fingers

Aufbau Principle

Electrons occupy the lower energy orbitals first, unless electrons are excited.
“Quantum Ladder”

Pauli Exclusion Principle

No two electrons can have the same quantum numbers.
Each orbital can hold a maximum of two electrons with opposite spins.

Hund’s Rule

Electrons fill orbitals singly before pairing up to minimize repulsion.
Orbital is stable when as many electrons have the same spin.

Mnemonic for Electron Configuration

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