Download Atomic Orbitals

Ch. 13.1: The Quantum Mechanical Model


Define Quantum
Explain the significance of quantized energies
of electrons as they relate to the quantum
mechanical model of the atom.


A quantum of energy is the amount of energy
required to move an electron from its present
energy level to the next higher one.
The energy of electrons is said to be
quantized.


Quantum number
refers to major energy
level in the atom. (in
increasing order)
Denoted by “n”
◦ n= 1,2,3,4,5,…

The distance between
the electron and
nucleus increases with
each rise in energy
level.
The distance between the
electron and nucleus
___________ with each rise
in energy level.
Increases

4 different sublevels
: they are denoted by
letters.
◦
◦
◦
◦
s
p
d
f
These are the rows of
the movie theater
sections. These are
called Atomic Orbitals.

The first orbital is
“s”.
◦ It has a spherical
shape.
◦ There is only one
type of “s” orbital.
◦ Compare they
electrons in “s”
orbital w/ those in
Bohr Model.
Representations of Orbitals
The s-Orbitals

The second orbital is
“p”.
◦ It has a dumbbell-like
shape.
◦ There are three
different kinds of “p”
orbitals. They have
different orientations
◦ px, py, pz
◦ Where are the
electrons?

The third orbital is
“d”.
◦ It has a shape
somewhat like a
four-leaf clover
◦ There are 5 types of
“d” orbitals.
◦ Where are the
electrons?

The fourth orbital is
“f”.
◦ It has a very complex
shape. In fact it is
too complex to even
fathom!
◦ There are 7 different
“f” orbitals
How many electrons can an
orbital within a sublevel
hold?
Principal Energy Level
Number Types of Sublevels
of
Sublevels
n=1
1
1s (1 orbital)
n=2
2
2s (1 orbital), 2p (3 orbitals)
n=3
3
3s (1 orbital), 3p (3orbitals),
3d (5 orbitals)
n=4
4
4s (1 orbital), 4p (3 orbitals),
4d (5 orbitals), 4f (7 orbitals)

The maximum number of electrons that can
occupy a principal energy level is given by the
formula 2n2 .
Increasing energy
(increasing distance from the nucleus)
Energy
Level “n”
1
2
3
4
Max # of 2
Electrons
allowed
8
18
32

Ch.13 Section 1 p.366
◦ #3 & #4
Ch. 13 Chapter Review p. 386
#24 & #25
ORBITAL DIAGRAMS AND ELECTRON
ARRANGEMENT IN ATOMS
CH. 13.2:
E L E C T R O N C O N F I G U R AT I O N
REVAMPED
ELECTRON
CONFIGURATION AND
THE PERIODIC TABLE
•Each row is called a “period”
ELECTRON CONFIGURATION PERIODIC TABLE
“Like a running back, get it, man I’m straight off the block”
ORBITAL DIAGRAMS (AUF BAU DIAGRAM)
An orbital diagram is a
pictorial description of how
electrons are arranged in an
atom.
ORBITAL DIAGRAMS
Three rules that dictate how electrons are arranged.
1. Aufbau Principle - electrons enter orbitals of lowest energy first.
See diagonal chart or periodic table.
Electrons do not fill in orbitals in consecutive numerical order.
ORBITAL ENERGY DIAGRAM
The boxes are the individual atomic orbitals and they are to
be filled with electrons.
Orbitals and Their Energies
Many-Electron Atoms
AUF BAU PRINCIPLE
Electrons enter the orbitals
in the direction of the
arrows. This pattern
continues through the “f”
orbitals.
ORBITAL DIAGRAMS
2. Pauli Exclusion Principle - an atomic orbital can hold
a maximum of 2 electrons and those 2 electrons must
have opposite spins
Many-Electron Atoms
Electron Spin and the Pauli Exclusion
Principle
ORBITAL DIAGRAMS
3. Hund’s Rule - When electrons occupy orbitals of equal energy
(same sublevel), one electron enters each orbital with parallel
spin before pairing oppositely.
Example:
a 2p sublevel with 3 electrons
a 3d sublevel with 8 electrons
ORBITAL DIAGRAM PRACTICE
Draw Orbital Diagrams for the following Elements:
Be –
S-
Fe –
Ge -
HOMEWORK
Study Guide: Periodic table, Atomic Orbitals, Orbital
Diagrams, and Electron Configuration Worksheet
• Due Friday Jan, 14th
• Test on Wednesday 19th
ELECTRON CONFIGURATION
The way in which electrons are arranged
around the nucleus according to energy
specifications.
ELECTRON CONFIGURATION
Orbital diagram – orbital is a box grouped by sublevel containing arrow(s) to
represent electrons
Orbitals and Their Energies
Many-Electron Atoms
HE ATOM
 Electron configuration– 1s2
 Orbital diagram
LI ATOM
 Electron configuration– 1s2 2s1
 Orbital diagram
ELECTRON CONFIGURATION PRACTICE
Cl Ne Sr -
A. ELECTRON ARRANGEMENTS IN THE FIRST 18 ATOMS ON
THE PERIODIC TABLE
Classifying Electrons
Valence electrons – electrons in the outermost (highest) principal energy level of an atom
Core electrons – inner electrons
Elements with the same valence electron arrangement show very similar chemical behavior.