1. n = The principle quantum number
Quantum Mechanics
In quantum mechanics, the electrons occupy specific energy levels (as in Bohr's model) but they also exist within specific probability volumes called orbitals with specific orientations in space. The electrons within each orbital has a distinct spin.
n = The principle quantum number
Describes the possible energy levels and pictorially it describes the orbital size.
n = 1, 2, 3…. where an orbital with the value of 2 is larger than an orbital with the value of 1. 2s 1s

2. Quantum Mechanics l = angular momentum quantum number
Describes the "shape" of the orbital and can have values from 0 to n - 1 for each n.
orbital designation : s p d f
shape :
ml = magnetic quantum number
Related to the orientation of an orbital in space relative to the other orbitals with the same l quantum numbers. It can have values between l and - l .
ms = spin quantum number
An electron has either +1/2 or -1/2 spin values; sometimes referred to as spin up and spin down.
Too hard to draw
see text

3. Orbital Shapes

4. Electron Configuration
Electron configuration is a shorthand notation for describing the arrangement of the electrons about the nucleus.
General Format using the quantum numbers:
n l e-
RULES:
1. Fill the lowest energy levels first.
1s 2s 2p 3s 3p 4s 3d 4p
2. No more than two electrons per orbital.
n = principle quantum number
l = angular momentum quantum number
e- = number of electrons
Lowest

5. Electron Configuration
Examples:
H : 1s1 He: 1s2 Li : 1s2 2s1
Co: 1s2 2s2 2p6 3s2 3p6 4s2 3d7
Br: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5
The condensed electron configuration distinguishes the core electrons from the valence electrons. CORE electrons are tightly held to the nucleus and resemble a noble gas configuration. VALENCE electrons are the outer most electrons and are involved in chemical reactions.
Examples of the condensed configuration:
Li:[He] 2s1 Co:[Ar] 4s2 3d7
Br:[Ar] 4s2 3d10 4p5

6. Electron Configuration Practice Problems
1. Give the full electron configuration:
C O Ne Na Si Cl Ar K
2. Give the condensed electron configuration:
Answers on next slide

7. Electron Configuration
Answers
1 & 2. Give the full & condensed electron configuration:
C 1s2 2s2 2p or [He] 2s2 2p2
O 1s2 2s2 2p or [He] 2s2 2p2
Ne 1s2 2s2 2p6 or [Ne]
Na 1s2 2s2 2p6 3s or [Ne] 3s1
Si 1s2 2s2 2p6 3s2 3p2 or [Ne] 3s2 3p2
Cl 1s2 2s2 2p6 3s2 3p5 or [Ne] 3s2 3p5
Ar 1s2 2s2 2p6 3s2 3p6 or [Ar]
K 1s2 2s2 2p6 3s2 3p6 4s1 or [Ar]4s1

8. Orbital Diagrams ___ ___ ___ 4p ___ ___ ___ ___ ___ 3d ___ 4s
Orbital diagrams are written in order of increasing energy levels starting with the lowest energy level the 1s orbital.
___ ___ ___ 4p
___ ___ ___ ___ ___ 3d
___ 4s
___ ___ ___ 3p
___ 3s
___ ___ ___ 2p
___ 2s
___ 1s
RULES:
(1) fill the lowest energy level first
(2) fill each orbital in a subshell with one electron first before you double up.
(3) Completely fill each subshell before proceeding to the next energy level.
Remember the order!!

9. Orbital Diagrams Practice Problems
1. Fill in the orbital diagrams for:
C O Ne Na Si Cl Ar K
___ ___ ___ 4p ___ ___ ___ 4p
__ __ __ __ __ 3d __ __ __ __ __ 3d
___ 4s ___ 4s
___ ___ ___ 3p ___ ___ ___ 3p
___ 3s ___ 3s
___ ___ ___ 2p ___ ___ ___ 2p
___ 2s ___ 2s
___ 1s ___ 1s

10. Orbital Diagrams Practice Problem Answers
Fill in the orbital diagrams for:
C O
___ ___ ___ 4p ___ ___ ___ 4p
__ __ __ __ __ 3d __ __ __ __ __ 3d
___ 4s ___ 4s
___ ___ ___ 3p ___ ___ ___ 3p
___ 3s ___ 3s
___ ___ ___ 2p ___ ___ ___ 2p
___ 2s ___ 2s
___ 1s ___ 1s

11. Orbital Diagrams Practice Problem Answers
Fill in the orbital diagrams for:
Ne Na
___ ___ ___ 4p ___ ___ ___ 4p
__ __ __ __ __ 3d __ __ __ __ __ 3d
___ 4s ___ 4s
___ ___ ___ 3p ___ ___ ___ 3p
___ 3s ___ 3s
___ ___ ___ 2p ___ ___ ___ 2p
___ 2s ___ 2s
___ 1s ___ 1s

12. Orbital Diagrams Practice Problem Answers
Fill in the orbital diagrams for:
Si Cl
___ ___ ___ 4p ___ ___ ___ 4p
__ __ __ __ __ 3d __ __ __ __ __ 3d
___ 4s ___ 4s
___ ___ ___ 3p ___ ___ ___ 3p
___ 3s ___ 3s
___ ___ ___ 2p ___ ___ ___ 2p
___ 2s ___ 2s
___ 1s ___ 1s

13. Orbital Diagrams Group Study Problems
Fill in the orbital diagrams and then write the electron configuration (both full and condensed) for:
B F Ca P S As Zn Pb
___ ___ ___ 4p
__ __ __ __ __ 3d
___ 4s
___ ___ ___ 3p
___ 3s
___ ___ ___ 2p
___ 2s
___ 1s