Transcript The Quantum Model : Part II

The Quantum Model :
Part II
Electron Configurations
Quantum Numbers
Describe the properties of atomic orbitals and
the electrons that occupy them…
Quantum Number
Describes
 Principle
main E. level
 Angular Momentum shape of Orbital
 Magnetic
orientation of orbital
 Spin
orientation of electron

Principal Quantum Number (PQN)
Main energy level occupied by the electron
 Distance from nucleus
 “shell”
 Always whole
positive integers

Angular Momentum Quantum
Number (orbital)
Shape of the orbital
 Sublevel within the main energy level

s orbitals
p orbitals
d orbitals
Magnetic Quantum Number


Orientation of orbital
(X, Y, Z)
Has to do with the
relation to the x-y-z
axes
s Orbitals have only one possible
orientation.
P Obitals have 3 possible orientations
d Orbitals Have 5 Orientations
How many orientations do you
think f orbitals have?
SPIN QUANTUM NUMBER

The orientation of the electron in the
orbital.

“Direction of its spin”.

An electron can only have 2 different
types of spins

We will call the two types of spins “UP”
and “DOWN”
How many sublevels are
allowed for each energy
level?
 We
are not actually filling the energy
level. We are filling sub-levels that
make up the energy level.
 We start with the lowest energy sublevel
 The S, when we fill this we have to
move to a higher energy sub-level
 Next we enter the P orbitals, after
filling these we enter the D orbitals …
Given by the Quantum-Mechanical Model
of the Atom
 There can only be 0 … n-1 sublevels for
each energy level, this means:


The 1st energy level has 1 sublevel

The 2nd energy level has 2 sublevels

The 3rd energy level has 3 sublevels

The 4th energy level has 4 sublevels
Atomic Orbitals and Quantum
Numbers
Use your notes to make a chart showing
important information about each of the four
quantum numbers. Make chart for only
n=1,2,3,4
Principal Quantum Number
 Angular Momentum Quantum Number
 Magnetic Quantum Number
 Spin Quantum Number

HOMEWORK
Read pages 101 – 104,

Answer questions #1-3 on page 104

Answer question # 14, 15, 16 on pg 118

Read the Lab for a pre-lab quiz next class
Your Chart Should look like this
Principle
Quantum #
Angular
Momentum
Quantum #
Magnetic
Quantum #
Spin
Quantum #
Energy
Level
Sublevels
Orientation
Orbital
Orientation
Electron
1
(s)
1
Up/down
2
(s,p)
4
Up/down
3
(s,p,d)
9
Up/down
4
(s,p,d,f)
16
Up/down
Electron Configuration
Show the placement of electrons in
specific levels, sublevels and orbitals.
 Make use of the four quantum numbers
and a few simple rules.
 Each orbital can only hold a maximum of 2
electrons
 Before we learn the rules lets look at a few
examples!

Types of notation
Orbital diagram
 Arrows represent electrons and direction of
spin.
 Which element is this? How many electrons?

Rule # 1 : Aufbau Principle
An electron occupies the lowest energy
orbital that can receive it…(like filling a
glass)
 n= 1, n= 2, n=3 represent main energy
level.

Organize the levels and sublevels
Main energy level, 1, 2, 3 etc.)
 How many sublevels exist at each main
energy level?
 What are the sublevels at each main energy
level?

1__
2__
3__
4__
5__
2__
3__
4__
5__
3__
4__
5__
4__
5__
5__
Organize the levels and sublevels

Principle Quantum Number (main energy
level)
↓
1s
2s
3s
4s
5s
2p
3p
4p
5p
3d
4d
5d
4f
5f
5g
How do we remember which
sublevel to fill first?

Memory Aid Diagram
Rule # 2 : Pauli exclusion principle
No two electrons in the same atom can
have the same set of four quantum
numbers…or…
 If two electrons occupy the same orbital
they must have opposite spins!

He ↑ ↓
1S
opposite spins shown by arrow.
Rule # 3 : Hund’s Rule

Orbitals of equal energy are each occupied by
one electron before any orbital is occupied by a
second electron.
Correct
Wrong
Electron configuration notation
1S2 2S2 2P2
What does each character represent?
Which element is this?
The Three Little Rules!



An electron occupies the lowest energy orbital
that can receive it…(like filling a glass)
If two electrons occupy the same orbital they
must have opposite spins!
Orbitals of equal energy are each occupied by
one electron before any orbital is occupied by a
second electron.
Homework

Read pg 105 – 111

Questions: pg 116 #1

Work on electron configuration handout