Quantum Chemistry and Electron Configurations

Electron Configuration

Mr.Mendoza

Orbitals

a region of probability where an electron can be found.

s

d

p

f

Remember these are NOT electrons, they're just regions of space where an electron can be found.(Each can hold up to 2 electrons)

The 4 Quantum Numbers

Describe different atomic orbitals

n=Principle Quantum Number

l= Angular Momentum Quantum Number 
 $M_l$  =Magnetic Quantum Number 
 $M_s$  =Spin Quantum Number

Principle Quantum Number

n=1

n=2

n=3

n=4

Angular Momentum Quantum Number

Determines the shape of an orbital

Each value of l

l indicates a specific s, p, d, f subshell (each unique in shape.

he value of l

l is dependent on the principal quantum number n

n.

l=0,1,2,3,4...,(n-1)

Magnetic Quantum

Determines the number of orbitals and their orientation within a subshell

s=1

d=3

p=5

f=7

Spin Quantum

designates the direction of the electron spin and may have a spin of +1/2, represented by↑, or –1/2, represented by ↓

Pauli Exclusion Principle

No two electrons in the same atom can have identical values for all four of their quantum numbers.

In other words:

(1) no more than two electrons can occupy the same orbital

(2) two electrons in the same orbital must have opposite spins 

Aufbau Principle

states that electrons fill lower-energy atomic orbitals before filling higher-energy ones (Aufbau is German for "building-up")

Hunds Rule

every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied, and all electrons in singly occupied orbitals have the same spin.

Orbital Configuration

the more visual way to represent the arrangement of all the electrons in a particular atom

Each sublevel is labeled by its principal energy level and sublevel

Electrons are indicated by arrows inside the circles. An arrow pointing upwards indicates one spin direction, while a downward pointing arrow indicates the other direction.

Electron Configuration

Electron configuration notation eliminates the boxes and arrows of orbital filling diagrams.