Quantum Numbers and Orbitals

Quantum Number

these numbers define the orbitals and electrons within these numbers mathematically; describe shape, size, energy, etc.

n, The Principal Quantum Number

a positive integer describing relative size and energy of an atomic orbital; if n increases, size and energy increases

Orbital

a 3D region where the probability of finding an electron is the highest

l, The Angular Momentum Number

defines orbitals shape, ranges from 0 to n-1

Ml, The Magnetic Quantum Number

describes the orientation of the orbital in space; ranges from -l to l

Ms, The Spin Quantum Number

an integer describing the spin of electrons in the orbital, (-1/2 or +1/2 only). Each orbital can hold 2 electrons, one +1/2, and one -1/2.

Aufbau Principle

add electrons to the lowest energy orbital first

Pauli's Exclusion Principle

electrons in a given atom cannot share the same 4 quantum numbers.

Degenerate

if two orbitals have the same n+1 value, they have equal energy and are called degenerate.

Hund's Rule

when filling degenerate orbitals, it's best to leave unpaired electrons

Electron Configuration

denotes number of electrons in each orbital

Orbital Diagrams

a box as the orbital, half-arrow as electron

Condensed Electron Configuration

Core Electrons

electrons in the inner shells; not very reactive

Valence Electrons

electrons in outer shells; very reactive