1. Quantum Model
of the Atom
Electrons in Atoms

2. Quantum Mechanics
Radial Distribution CurveOrbital
Orbital (“electron cloud”)
Region in space where there is 90%
probability of finding an e-

3. Quantum Numbers
UPPER LEVEL
Four Quantum Numbers:
Specify the “address” of each electron in
an atom

4. Quantum Numbers
1. Principal Quantum Number ( n )
Energy level
Size of the orbital
n2
= # of orbitals in
the energy level

5. Quantum Numbers
s p d f
2. Angular Momentum Quantum # ( l )
Energy sublevel
Shape of the orbital

6. Quantum Numbers
n = # of sublevels per level
n2
= # of orbitals per level
Sublevel sets: 1 s, 3 p, 5 d, 7 f

7. Quantum Numbers
3. Magnetic Quantum Number ( ml )
Orientation of orbital
Specifies the exact orbital
within each sublevel

8. C. Quantum Numbers
px py pz

9. C. Quantum Numbers
Orbitals combine to form a spherical shape.
2s
2pz
2py
2px

10. Quantum Numbers
4. Spin Quantum Number ( ms )
Electron spin ⇒ +½ or -½
An orbital can hold 2 electrons that spin
in opposite directions.

11. Quantum Numbers
1. Principal # →
2. Ang. Mom. # →
3. Magnetic # →
4. Spin # →
energy level
sublevel (s,p,d,f)
orbital
electron
Pauli Exclusion Principle
No two electrons in an atom can have
the same 4 quantum numbers.
Each e-
has a unique “address”:

12. General Rules
Aufbau Principle
Electrons fill the
lowest energy
orbitals first.
“Lazy Student
Rule”

13. General Rules
The Diagonal Rule
2p
3p
4p
5p
6p
7p
3d
4d
5d
6d
4f
5f
2s
3s
4s
5s
6s
7s
1s
8s

14. WRONGRIGHT
General Rules
Hund’s Rule
Within a sublevel, place one e-
per
orbital before pairing them.
“Empty Bus Seat Rule”

15. O
8e-
Orbital Diagram / Box & Arrow Diagram
Electron Configuration / SPDF Notation
1s2
2s2
2p4
Notation
1s 2s 2p

16. Shorthand Configuration
S 16e-
Valence ElectronsCore Electrons
S 16e-
[Ne] 3s2
3p4
1s2
2s2
2p6
3s2
3p4
Notation
Longhand Configuration

17. © 1998 by Harcourt Brace & Company
s
p
d (n-1)
f (n-2)
1
2
3
4
5
6
7
6
7
Periodic Patterns

18. Periodic Patterns
Period #
energy level (subtract for d & f)
A/B Group #
total # of valence e-
Column within sublevel block
# of e-
in sublevel

19. s-block1st Period
1s1
1st column
of s-block
Periodic Patterns
Example - Hydrogen

20. 1
2
3
4
5
6
7
Periodic Patterns
Shorthand Configuration
Core e-
: Go up one row and over to the
Noble Gas.
Valence e-
: On the next row, fill in the #
of e-
in each sublevel.

21. [Ar] 4s2
3d10
4p2
Periodic Patterns
Example - Germanium

22. Full energy level
1
2
3
4
5
6
7
Full sublevel (s, p, d, f)
Half-full sublevel
Stability

23. Electron Configuration Exceptions
Copper
EXPECT: [Ar] 4s2
3d9
ACTUALLY: [Ar] 4s1
3d10
Copper gains stability with a full
d-sublevel.
Stability

24. Electron Configuration Exceptions
Chromium
EXPECT: [Ar] 4s2
3d4
ACTUALLY: [Ar] 4s1
3d5
Chromium gains stability with a half-full d-sublevel.
Stability

25. Stability
Ion Formation
Atoms gain or lose electrons to become more
stable.
Isoelectronic with the Noble Gases.

26. O2-
10e-
[He] 2s2
2p6
Stability
Ion Electron Configuration
Write the e-
config for the closest Noble
Gas
EX: Oxygen ion → O2-
≡ Ne