ELECTRON DISTRIBUTION LAB
WHAT IS AN ELECTRON CONFIGURATION?
The arrangement
of electrons in an
atom
THREE RULES TO REMEMBER…
• 1. Aufbau Principle
• 2. Pauli Exclusion Principle
• 3. Hund’s Rule
AUFBAU PRINCIPLE
• States that each electron occupies the lowest energy orbital
available
• Must learn the sequence of atomic orbitals from lowest energy to
highest energy
• Called the Aufbau diagram!
• Each box represents an atomic orbital
HOW TO REMEMBER THE AUFBAU PRINCIPLE
• Principal
quantum
numbers are like
floors of a hotel
• e- enters the
lowest level first
PAULI EXCLUSION PRINCIPLE
• Electrons in orbitals can be represented by arrows in boxes.
• Every electron has an associated spin
• Can only spin two ways
Represents electron spinning in one direction
Represents electron spinning in opposite direction
Represents unoccupied orbital
Represents a filled orbital
Pauli Exclusion Principle
States that a maximum of TWO electrons can occupy a single
atomic orbital, but only if they have opposite spins.
HOW TO REMEMBER
THE PAULI EXCLUSION PRINCIPLE
• Spin one index finger away from you
• Spin the other index finger toward you
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 orbital.
How to Remember….
Strangers on a Bus!
Do you sit next to a stranger… or pick an empty seat?
Pick an empty seat, unless there isn’t one, then you sit with
the stranger…
Orbital Diagram for Phosphorus
ORBITAL DIAGRAMS CONT.
• Draw the orbital diagram for
• Sodium
• Chlorine
ORBITAL & ELECTRON CONFIGURATION NOTATION
ELECTRON CONFIGURATION NOTATION
1s
Silicon
2s
2p
3s
3p
3d
4s
4p
4d
5f
5s
5p
5d
5f
6s
6p
6d
7s
7f
Remember
•
•
•
•
1 s-orbital
3 p-orbitals
5 d-orbitals
7 f-orbitals