Transcript Last 3 addresses of the e

Electron Configurations
The 2nd address of the e-
Electron Configurations
Electron configurations are a list of all the
electrons in an atom (or ion).


Electrons are attracted to a nucleus. They
will move around the nucleus in predictable
patterns. They will fill up available space
inside the atom’s e- cloud.
The Spaces allotted to electrons are inside
the energy levels and are sub-energy levels
or orbitals named s, p, d, & f.
A maximum of two electrons can be
placed in any one orbital.
How many electrons can be in a sublevel?
Number of
Orbitals in
Sub-energy
level
Number of
electrons in
sub-energy
level
S
p
d
f
sub-energy
sub-energy
sub-energy
sub-energy
1
3
5
7
2
6
10
14
How do electrons
fill orbitals?
Aufbau principle
To Build up….
states that electrons fill
from the lowest
possible energy to the
highest energy
4f
Main energy
level
n=4
E
N
E
R
G
Y
n=3
n=2
n=1
14 e-
Max # of e4d
10 e-
4p
6 e-
3d
4s
10 e-
3p
6 e-
32 e-
18 e-
2 e-
3s
2 e-
2p
6 e-
2s
2 e-
1s
2 e-
8 e-
2 e-
Sub-energy level
e- per orbital
Electron Configurations
2
3p
Energy Level
Number of
electrons in
the sublevel
Sublevel
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6
6s2 4f14… etc.
Diagonal Rule
Steps:
1s
2s
3s
1.
Write the energy levels top to bottom.
2.
Write the orbitals in s, p, d, f order. Write
the same number of orbitals as the energy
level.
3.
Draw diagonal lines from the top right to the
bottom left.
4.
To get the correct order,
2p
3p
3d
follow the arrows!
4s
4p
4d
4f
5s
5p
5d
5f
6s
6p
6d
6f** 6g** 6h**
7s
7p
7d** 7f** 7g** 7h** 7i**
5g**
**By this point, we are past
the current periodic table
so we can stop.
Let’s Try It!
 Write the electron configuration
for the following elements:
K, Zn, Pb
K
Zn
Pb
1s2 2s2 2p6 3s2 3p6 4s1
1s2 2s2 2p6 3s2 3p6 4s2 3d10
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10
5p6 6s2 4f14 5d10 6p2
Shorthand
Notation
 We
are only concerned about
the outermost electrons.
 We can use the noble gases as a
method to represent all
completely filled sub-energy
levels.
Shorthand
Notation
Step 1: It’s the Showcase Showdown!
Find the closest noble gas to the atom,
WITHOUT GOING OVER the number
of electrons in the atom
Write the noble gas in brackets [ ].



Step 2: Find where to resume by finding
the next energy level.
Step 3: Start with that energy level and
use the __s2 Resume the configuration
until it’s finished.
Shorthand
Notation
Chlorine  Longhand is
1s2 2s2 2p6 3s2 3p5
You can abbreviate the first 10 electrons
with the noble gas, Neon.
[Ne] replaces 1s2 2s2 2p6
3 is the next energy level after Ne So you
start at level 3 with the diagonal rule
(all levels start with s) Finish the
configuration by adding 7 more e- to total 17
The Shorthand for Cl [Ne] 3s2 3p5
Practice Shorthand Notation
 Write
the shorthand notation for each
of the following atoms:
Ca, I, Bi
Ca [Ar]4s2
I
[Kr]5s2 4d10 5p5
Bi [Xe]6s2 4f14 5d10 6p3
Electron configuration of the
elements of the first three series
HOW ‘BOUT A SONG
TO HELP YOU
FIGURE IT OUT!!
e- configuration polka
There’s a little game that’s as easy as can be,
With numbers & letters & lots of chemistry.
It comes from quantum theory & wave
mechanic stuff,
But for now just learn the game & that will be
enough.
e configuration polka
Chorus
1s2, 2s2 then comes 2p6,
The e- configuration game is really slick.
From the alkali to halogen and on to noble gas,
Now you can understand the Periodic Law at last.
e- configuration polka
Atoms have orbitals where e- like to play
And those e- fill the orbitals in a special way.
It’s a “building up” process-you can learn it in a second.
And you can call it “Aufbau” if Deutsch is what you
sprechen.
e configuration polka
Chorus
1s2, 2s2 then comes 2p6,
The e- configuration game is really slick.
From the alkali to halogen and on to noble gas,
Now you can understand the Periodic Law at last.
e- configuration polka
The outermost e- in atoms have to be,
The most important ones for understanding chemistry.
These valence e- are shared, or lost or gained,
In chemical reactions when atoms rearrange.
e configuration polka
Chorus
1s2, 2s2 then comes 2p6,
The e- configuration game is really slick.
From the alkali to halogen and on to noble gas,
Now you can understand the Periodic Law at last.
e configuration polka
But the joy is that now… in this point in history,
We can finally solve the periodic table mystery.
Why do elements form families, what is the explanation?
Their valence e- have the same configuration.
e configuration polka
Chorus
1s2, 2s2 then comes 2p6,
The e- configuration game is really slick.
From the alkali to halogen and on to noble gas,
Now you can understand the Periodic Law at last.
Exceptions to the Aufbau
Principle

Chemistry wouldn’t be any fun if it didn’t throw
you a curve ball every now and then.
Some Atoms break the rules because they can
exist in a configuration that maintains a lower
energy.
 There are many exceptions, but the most common
ones are atoms that end with a

d4 and d9 configuration.
Exceptions to the Aufbau
Principle
d4 is one electron short of being HALF full
↑ ↑ ↑ ↑
__

In order to become more stable one of the closest
s electrons will actually move over to the open d
orbital.
Ex.: Cr by rule would be [Ar] 4s2 3d4
The Exception makes it, [Ar] 4s1 3d5.
Procedure: Find the closest s orbital. Steal 1
electron from it, and add it to the d. This will
create a ½ filled lower energy, more stable
configuration.
Exceptions to the Aufbau
Principle
OK, so this helps the d, but what about the poor s
orbital that loses an electron?
Remember, half full is good… and when an s loses 1, it too
becomes half full!
So… having the s half full and the d half full is usually a
lower energy configuration than leaving the s full and
the d sub-energy level with one empty orbital.
Exceptions to the Aufbau
Principle
d9 is one electron short of being full
↑↓ ↑↓ ↑↓ ↑↓ ↑_

Just like d4, one of the closest s electrons will go into the d,
this time making it d10 instead of d9.
Ex: Au by rule would be [Xe] 6s2 4f14 5d9,
The exception makes it [Xe] 6s1 4f14 5d10
Procedure: Same as before! Find the closest s orbital.
Steal one electron from it, and add it to the d.
Irregular confirmations of Cr and Cu
Chromium steals a 4s electron to
half fill its 3d sublevel
Copper steals a 4s electron to FILL
its 3d sublevel
Try These Exceptions
Write
the shorthand
notation for:
Cu, W
1
4s
10
3d
Cu [Ar]
1
14
5
W [Xe] 6s 4f 5d
Electron Notations
The 3rd address of the e-
Orbital Diagrams
Graphical representation of an
electron configuration
Arrows are used to represent electrons.
The direction and position of each arrow identifies
the spin and which orbital within a
sublevel an e- exists.
Same rules apply
1.
2.
3.
Aufbau principle
Pauli’s Exclusion principle
Hund’s Rule
Orbital Diagrams

Hund’s Rule
In orbitals of EQUAL
ENERGY (p, d, and f),
electrons will fill in
each orbital before
pairing up.
In Monopoly, you have to build
houses EVENLY. You can not put
2 houses on a property until all
the properties in the set have at
least 1 house.
Lithium
Group 1A
Atomic number = 3
1s22s1 ---> 3 total
electrons
  .
1s 2s
Carbon
Group 4A
Atomic number = 6
1s2 2s2 2p2
   
1s 2s
2p
.
Here we see for the first
time HUND’S RULE.
When placing electrons in
a set of orbitals having the
same energy, we place
them singly without pairing
up.
Draw these orbital diagrams!
O, Cr, Hg
O = [He]     .
2s
2p
Cr = [Ar]      
4s
3d
{Exception to Aufbau}
Hg = [Xe]             
6s
4f
5d
Quantum Numbers
The Final address of the e-
The zip code of the electron!
Quantum Numbers
Describe the location of electrons in an atom
1)
2)
3)
4)
n – principal (energy level)
l – azimuthal (energy sublevel)
m – magnetic (orbital)
s – spin (direction of electron spin)
No two electrons in the same atom can have
the same set of all four quantum numbers!
Assigning the Numbers
 The three quantum numbers (n, l, and m) are integers.
 The principal quantum number (n) cannot be zero.
n must be 1, 2, 3, etc.
 The angular momentum quantum number (l) can be any
integer between 0 and n - 1.
Ex. For n = 3, l can be either 0, 1, or 2.
 The magnetic quantum number (m) can be any integer
between -l and +l.
Ex. For l = 2, m can be either -2, -1, 0, +1, or +2.
Quantum Numbers
What are the quantum
numbers of the
last electron placed
on Aluminum.
Quantum Numbers
The Steps
1. Write out e- configurations for the element.
2. Determine the e- notations for the element.
Identify the last placed e-
Example:
Al  1s2, 2s2, 2p6, 3s2, 3p1
Last placed electron
Al [Ne] ↑↓
↑_ __ __
Quantum Numbers
3. Identify each quantum number for the last eplaced in the highest energy orbital.
n  the energy level of the en = 1,2,3,..7
l  the sub-energy of the el = {s = 0, p=1, d=2, f=3}
m  the specific orbital in which the e- is located.
(Treat as a number line)
m=
0
-1 0 +1 -2 -1 0 +1 +2
-3 -2 -1 0 +1 +2 +3
s
p
d
f
s  The specific e- in the orbital. s = +½ for 1st e- (up arrow)
s = -½ for 2nd e- (down arrow)
Quantum Numbers
-1 0 +1
Ex.: Al [Ne] ↑↓
3s
↑_ __ __
3p
Al Last placed e- has the quantum #s
n = 3 , l = 1, m = -1, s = +½
Quantum Numbers
Determine the Quantum # for these
elements.
Mg, Zn, and Kr
Mg  [Ne] 3s2    3, 0, 0, -½
Zn  [Ar] 4s2, 3d10 
     
Kr  [Ar] 4s2, 3d10, 4p6 

 3,2,2, -½
    
  
 4, 1, 1,-½
Quantum Numbers
Try to name these elements!!
A)
3, 1, -1, -½
3p4  Sulfur
B)
4, 1, 0, +½
4p2  Germanium
c)
3, 2, -2, -½
3d6  Iron