ELECTRON CONFIGURATION

HOTEL CHEMISTRY

• Welcome to the electron hotel ……what a lovely place!

• Imagine you are the owner of a hotel.

• Rooms are filled up in a certain order.

• You want to fill the rooms on the lower floors first.

• Each room can only hold a certain number of people.

• Each room can only hold 2 people!

• Some rooms fill faster than others.

• Each person in a hotel can be found using their floor, room, and bed number.

• THIS IS JUST LIKE THE ELECTRONS AND THEIR ORBITALS!

ELECTRON HOTEL

QUANTUM MECHANICAL MODEL• Describes electrons

behaving as waves.• The exact location of the

electron is determined by Schrödinger’s wave equation.

• Describes the probable location of the electrons as a location in an orbital.

• The electron can be described using four quantum numbers.

ATOMIC ORBITAL• Principal quantum number (n)

• Principal energy level• n = 1-7

• Relative size and energy of atomic orbitals

• As n increases, the electron is further from nucleus, and atom’s energy level increases

• Angular quantum number (llll)• Describes the shape of the orbital

• (s, p, d, f)

• l = l = l = l = 0 to n-1

• Magnetic quantum number (mllll)

• x, y, z• m

llll= = = = ---- l l l l to + llll

• Electron spin quantum number (ms)• ↑ (up)

• ↓ (down)

• ms =+½ or -½

ORBITAL SUBLEVELS

• s, p, d, f• s orbital can hold 2 electrons

• p orbitals (3) can hold a total of 6 electrons

• d orbitals (5) can hold a total of 10 electrons

• f orbitals (7) can hold a total of 14 electrons

AUFBAU PRINCIPLE

• Aufbau Principle – Each electron occupies the lowest energy orbital available.

• Aufbau Diagram

• Each box represents an atomic orbital

PAULI EXCLUSION PRINCIPLE

• Pauli Exclusion Principle –a maximum of two electrons can occupy a single atomic orbital, but only if the electrons have opposite spins.

HUND’S RULE

• Hund’s Rule – single electrons with the same spin must occupy each equal-energy orbital before additional electrons with opposite spins can occupy the same orbitals

ELECTRON ARRANGEMENT

• Two methods:

• Orbital Diagrams

• Electron Configuration

• Orbital Diagrams

• Aufbau Diagrams

• Electron Configuration

• 1s1

1s1

Sub-level

# of electrons

(Orbital)

Energy level

ELECTRON CONFIGURATION & ORBITAL DIAGRAM

ELECTRON CONFIGURATION & ORBITAL DIAGRAM

• Energy level 1 = s orbital

• Energy level 2 = s, p orbital

• Energy level 3 = s, p, d orbital

• Energy level 4 = s, p, d, f orbital

• Energy level 5 = s, p, d, f orbital

• Energy level 6 = s, p, d orbital

• Energy level 7 = s, p orbital

PRINCIPLE QUANTUM

NUMBER(row or distance from

nucleus)

Size and energy

SUBLEVEL# ORBITALS IN

SUBLEVELMAX # e-

1 s 1 2

2 s p 1 3 8

3 s p d 1 3 5 18

4 s p d f 1 3 5 7 32

5 s p d f 1 3 5 7 32

6 s p d 1 3 5 18

7 S p 1 3 8

FILLING THE ORBITAL1s

2s 2p

3s 3p 3d

4s 4p 4d 4f

5s 5p 5d 5f

6s 6p 6d

7s 7p