The Quantum Mechanical Model

1
The Quantum Mechanical Model

• Erwin Schrodinger derived an equation that
  described the energy and position of the
  electrons in an atom

2
The Quantum Mechanical Model

• The atom is found inside a blurry electron
  cloud
• A area where there is a chance of finding an
  electron.
• Draw a line at 90
• Think of fan blades

3
Atomic Orbitals

• Principal Quantum Number (n) the energy level
  of the electron n 1 ? 7
• Schrodingers equation describes several shapes.
• These shapes are labeled with the letters s, p, d
  f

4
Atomic Orbitals

• The simplest sublevel is the s sublevel
• It only has 1 orbital per sublevel
• It holds 2 electrons

5
Atomic Orbitals

• The second sublevel is the p sublevel
• It has 3 orbitals per sublevel
• Each orbital holds 2 electrons
• Holds a total of 6 electrons

6
Atomic Orbitals

• The next sublevel is the d sublevel
• It has 5 orbitals per sublevel
• An orbital holds 2 electrons
• Holds a total of 10 electrons

7
Atomic Orbitals

• The last sublevel is the f sublevel
• It has 7 orbitals per sublevel
• Orbitals hold 2 electrons
• Holds 14 total electrons

8
 
9
Section 5.3Electron Arrangement in Atoms

• OBJECTIVES
• To learn to apply the proper order when writing
  the electron configurations of elements.

10
Section 5.3Electron Arrangement in Atoms

• OBJECTIVES
• Explain why the electron configurations for some
  elements differ from those assigned using the
  proper order.

11
Electron Configurations

• The way electrons are arranged in atoms.
• Aufbau principle- electrons enter the lowest
  energy first.
• Pauli Exclusion Principle- at most 2 electrons
  per orbital - different spins

12
Aufbau diagram - page 135
13
Electron Configuration

• Hunds Rule- When electrons occupy orbitals of
  equal energy they dont pair up until they have
  to.
• Lets determine the electron configuration for
  Phosphorus
• Need to account for 15 electrons

14

• The first two electrons go into the 1s orbital
• Notice the opposite spins
• only 13 more to go...

15

• The next electrons go into the 2s orbital
• only 11 more...

16

• The next electrons go into the 2p orbital
• only 5 more...

17

• The next electrons go into the 3s orbital
• only 3 more...

18

• The last three electrons go into the 3p orbitals.
• They each go into separate shapes
• 3 unpaired electrons
• 1s22s22p63s23p3

19
The easy way to remember

• 1s2

• 2 electrons

20
Fill from the bottom up following the arrows

• 1s2 2s2

• 4 electrons

21
Fill from the bottom up following the arrows

• 1s2 2s2 2p6 3s2

• 12 electrons

22
Fill from the bottom up following the arrows

• 1s2 2s2 2p6 3s2 3p6 4s2

• 20 electrons

23
Fill from the bottom up following the arrows

• 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2

• 38 electrons

24
Fill from the bottom up following the arrows

• 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2

• 56 electrons

25
Fill from the bottom up following the arrows

• 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2
  4f14 5d10 6p6 7s2

• 88 electrons

26
Fill from the bottom up following the arrows

• 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2
  4f14 5d10 6p6 7s2 5f14 6d10 7p6

• 108 electrons

27
Oxygen O
16
8

• 1s2

• 2 electrons

28
16
Oxygen O
8

• 1s2 2s2

• 4 electrons

29
16
Oxygen O
8
Stop! Once the e- the atomic number

• 1s2 2s2 2p4

The last sublevel does NOT have to be filled

• 8 electrons total

30
Try these

• Use your periodic tables to find the atomic
  numbers and the electron configurations of the
  following elements
• Aluminum
• Silicon
• Iron
• Uranium

31
Aluminum

• 1s22s22p63s23p1

Silicon
1s22s22p63s23p2
Iron
1s22s22p63s23p64s23d6
Uranium
1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p67
s25f4
32
Exceptional Electron Configurations
33
Stability and Special Orbital Arrangements

• In some cases orbitals are extra stable
• Full sublevels, s2, p6, d10, f14
• ½ full sublevels s1, p3, d5, f7
• If an element is close to ending with a half
  filled orbital it will borrow from the nearest
  s orbital

34
Write these electron configurations

• Chromium - 24 electrons
• 1s22s22p63s23p64s23d4 expected
• But this is wrong!!

35
Chromium is actually
4
5
1
2

• 1s22s22p63s23p64s 3d

This gives us two half filled orbitals.
36
Coppers electron configuration

• Copper has 29 electrons so we expect
  1s22s22p63s23p64s23d9
• But the actual configuration is
• 1s22s22p63s23p64s13d10
• This gives one filled orbital and one half filled
  orbital.
• Remember these exceptions d4, d9

37
Try these

• Silver
• Gold
• Molybdenum
• Unununium
• Tungsten

38
Noble-gas Notation

• Sometimes, the electron configurations can get
  long
• Noble-gas Notation a.k.a. shortform
• Use the noble gas at the end of a row to
  represent all the electron orbitals that are in
  that element

39
Noble-gas Notation
197

• Try Au
• 1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p67
  s25f4

79
This is the normal way to write out golds
electron configuration.
40
Noble-gas Notation
197

• Try Au
• 1s22s22p63s23p64s23d104p65s24d105p66s24f145d9

79
Find Au on the periodic table and go up 1 and all
the way to the right.
41
Noble-gas Notation
197

• Try Au
• 1s22s22p63s23p64s23d104p65s24d105p66s24f145d9

79
Use the noble gas at the end of the row to
substitute for the electrons in the first few
orbitals
42
Noble-gas Notation
Make sure that if you are using this notation for
a lanthanide or actinide that you only use a
noble gas as a short cut
197

• Try Au
• 1s22s22p63s23p64s23d104p65s24d105p66s24f145d9

79
This would be wrong.
43
Noble-gas Notation
The number that is in front of the bracketed
element should be smaller than the atomic number
of the element you are writing the configuration
for
197

• Try Au
• 1s22s22p63s23p64s23d104p65s24d105p66s24f145d9

79
This would be correct.
44
Noble-gas Notation
197

• Try Au

79
54Xe
All these electrons belong in
1s22s22p63s23p64s23d104p65s24d105p6
6s24f145d9
Notice how the 54, the 2, the 14 the 9 add up
to 79.
45
Noble-gas Notation
197

• Try Au

79
9
10
7s 5f146d
2
1
1
54Xe
Dont forget! Au ends in d9! So, steal from the
nearest s orbital
46
Noble-gas Notation
103

• Try Rh

45
47
Noble-gas Notation
197

• Try Au
• 1s22s22p63s23p64s23d104p65s24d105p66s24f145d9

79
Which noble gas would you use for the short cut
for element Rh?
36Kr Krypton
48
Noble-gas Notation
103

• Try Rh
• 5s24d7

45
1s22s22p63s23p64s23d104p6
36Kr
To see more examples of this notation, see table
5-4 on page 138
49
Lewis Dot Diagrams

• Electrons are very important in chemistry
• Especially those e-s found in the outer orbital
• These e-s are called Valence electrons
• Those found in the highest s and p orbitals

50
Electron-dot Structures

• To draw a electron dot structure
• Make the electron configuration
• Find the sublevels with the highest energy level
  number

51
Lewis Dot Diagrams

• Put dots around the symbol which equal the number
  of valence electrons

1 2
X
5 8
3 6
4 7
52
Electron-dot Structures

• Lets make the electron-dot structure for oxygen.

6 electrons 6 dots
16
O
O 1s22s22p4
8

• Find the sublevels that have the highest energy
  level number.
• Count the number of electrons in each sublevel
• Place the electrons around the symbol

53
Electron-dot Structures

• Lets make the electron-dot structure for oxygen.

6 electrons 6 dots
16
O
O 1s22s22p4
8

• To place the dots around the symbol properly,
• Place 2 on top to represent the 2s electrons
• Place one each around each other side before
  doubling up on any other side

54
Electron-dot Structures

• Lets make see that one more time

1
2
O
3
5
6
4
55
Lewis Dot Diagrams

• Br - 1s22s22p63s23p64s23d104p5
• The of valence e- for Br is 7
• Br

56
Electron-dot Structures

• Try making electron-dot structures for the
  following atoms
• 2He
• 20Ca
• 1H
• 74W
• All of the 2nd row elements

57
Electron-dot Structures

• Helium

He
58
Electron-dot Structures

• Calcium

Ca
59
Electron-dot Structures

• Hydrogen

H
60
Electron-dot Structures

• Tungsten

W
61
Electron-dot Structures

• 2nd row

Be
B
Li
C
N
O
F
Ne
62
Electron-dot Structures

• Carbon is wrong here for a special reason

Be
B
Li
C
N
O
F
Ne
63
Sp3 Hybrid Orbitals

• 1 s electron enters the p side
• Carbon and Silicon only
• Both have 4 valence electrons,

C
Si