Can you guess how many people are in this stadium?
If you attend a college or professional football game, you need a ticket to get in. It is very likely that your ticket may specify a gate number, a section number, a row, and a seat number. No other ticket can have the same four parts to it. It may have the same gate, section, and seat number, but it would have to be in a different row. Each seat is unique and allows only one occupant to fill it.
Quantum Numbers
We use a series of specific numbers, called quantum numbers, to describe the location of an electron in an associated atom. Quantum numbers specify the properties of the atomic orbitals and the electrons in those orbitals. An electron in an atom or ion has four quantum numbers to describe its state. Think of them as important variables in an equation which describes the threedimensional position of electrons in a given atom.
Principal Quantum Number (n)
The principal quantum number, signified by
Angular Momentum Quantum Number (l)
The angular momentum quantum number, signified as
Magnetic Quantum Number (ml)
The magnetic quantum number, signified as
for
for
Principal energy level  Number of possible sublevels  Possible Angular Momentum Quantum Numbers  Orbital Designation by Principal Energy Level and Sublevel 
1  1s  
2 

2s 2p 

3 

3s 3p 3d 

4 

4s 4p 4d 4f 
Table above shows the possible magnetic quantum number values
Spin Quantum Number (ms)
The spin quantum number describes the spin for a given electron. An electron can have one of two associated spins,
Summary
 Quantum numbers specify the arrangements of electrons in orbitals.
 There are four quantum numbers that provide information about various aspects of electron behavior.
Practice
Watch the video, pause at each question and try to calculate the quantum number before you see the answer written in. Do not try to answer the orbital questions, just the quantum number ones.
http://www.youtube.com/watch?v=DvlfMO3QlQw
Review
Questions
 What do quantum numbers do?
 What is the principal quantum number?
 What does the spin quantum number represent?