2. Electronic Configuration according to Quantum Mechanics
The location of an electron is described by 3 terms.
1st Term: Shell (n)
n = 3
n = 2
lone electron
of Hydrogen
n = 1

4. n = 3
2nd Term: subshell
- designated by s, p,d,f
n = 2 1s
The first shell (1) has one subshell (s).

5. 2nd Term: subshell
- designated by s, p,d,f
- refers to the shape(s) of
the area in which the electron
can be located.
- also designates an energy level
within the shell.
n = 3
n = 2 1s
The first shell (1) has one subshell (s).
The s subshell is spherical in shape and has 1 orbital
3rd Term: orbital

6. 2nd Term: subshell
- designated by s, p,d,f
- refers to the shape(s) of
the area in which the electron
can be located.
- also designates an energy level
within the shell.
n = 3
n = 2 1s
The first shell (1) has one subshell (s).
The s subshell is spherical in shape and has 1 orbital
3rd Term: orbital
Each orbital can accommodate
2 electrons

7. The Electronic Configuration of Hydrogen
energy
The first shell (1) has one subshell (s).
The s subshell is spherical in shape and has 1 orbital
Electronic configuration
H 1s1 1s
shell
# of electrons present
subshell
H 1s 
Orbital Energy Level Diagram

8. The Electronic Configuration of Helium
He: Atomic # of 2, 2 electrons in a neutral He atom 1s

9. The Electronic Configuration of Helium
He: Atomic # of 2, 2 electrons in a neutral He atom
H s1
He s2
He s  1s
**if there are 2 electrons in the same orbital
they must have the opposite spin. (Pauli’s Exclusion Principle)

11. The Electronic Configuration of Lithium (Li)
Li: Z=3 Li has 3 electrons.
2nd shell (2) 1s

12. The Electronic Configuration of Lithium (Li)
Li: Z=3 Li has 3 electrons.
- The 2nd shell (n= 2) has 2 subshells
which are s and p. 2p 2s
2nd shell 1s

13. The Electronic Configuration of Lithium (Li)
Li: Z=3 Li has 3 electrons. 2p 2s
2nd shell 1s
2s 
Li 1s 
Li s22s1
Electronic configuration
Orbital Energy Level Diagram

14. The Electronic Configuration of Berylium (Be)
Be: Z=4 Be has 4 electrons. 2p 2s
2nd shell 1s
2s 
Be 1s  
Be 1s22s2
Electronic configuration
Orbital Energy Level Diagram

16. - refers to the shape(s) of the area in which the electron
subshell
- designated by s, p,d,f
- refers to the shape(s) of
the area in which the electron
can be located.
- also designates an energy level
within the shell.
- relative energy: s < p < d < f
s subshell: spherical
1 orbital
p subshell: pair of lobes z x y x y z

17. Our Orbital Picture of Be
The first shell (1s) is filled.
The 2s orbital has 2 e- present.
The 2p orbitals are empty.
The 2p orbitals have room for 6 e-

19. The Electronic Configuration of Boron (B)
B: Z=5 B has 5 electrons. 2p 2p 2s 2s
2nd shell
2nd shell 1s 1s
Be 1s22s2
B 1s22s22p1
2p 
2s 
B s 
2s 
Be 1s 

20. The Electronic Configuration of Carbon (C)
C: Z=6 C has 6 electrons. 2p 2p 2s 2s
2nd shell
2nd shell 1s 1s
B 1s22s22p1
C 1s22s22px1py1
2p 
2s 
B 1s 
2p  
2s 
C s 

21. Our Orbital Picture of C
The first shell (1s) is filled.
The 2s orbital has 2 e- present.
2 2p orbitals have 1 e- each.

23. d subshell: double dumbellsx y xy yz xz z2
x2-y2

26. Atomic Radii within a Group+ e-
Hydrogen (Z=1); Shell (n)=1 + e-
2e-
Lithium (Z=3); n = 2
8e-
2e- + e-
Sodium (Z=11); n = 3

27. e- 2e- e- 2e- e- 2e- e- 2e- e- 2e- e- e- e- + + + + + Boron (Z=5)
Beryllium (Z=4)
n = 2
Lithium (Z=3)
n = 2
If protons were light bulbs….and electrons were moths…... B e- Li e- Be e-

28. e- 2e- e- 2e- e- 2e- Increasing Increasing + + + Boron (Z=5)
Beryllium (Z=4)
Boron (Z=5)
Lithium (Z=3)
Increasing
Increasing

30. First Ionization Energy+ e- H+
Hydrogen (Z=1) + e-
8e-
2e- + e-
2e-
Li+
Lithium (Z=3)
Sodium (Z=11) e-
8e-
2e- +
Na+

31. First Ionization Energy
Hydrogen (Z=1) e- +
Decreasing
Lithium (Z=3) +
2e- e-
Sodium (Z=11) +
2e-
8e- e-

32. e- e- 2e- 2e- 2e- e- e- e- e- Decreasing 1 e- removed = 2s0+ + + + + + + + e-
2e-
2e-
2e- e- e- e- e-
Beryllium (Z=4)
4 protons screened
by 2 e-
Boron (Z=5)
5 protons screened
by 2 e-
Lithium (Z=3)
3 protons screened
by 2 e-
1 e- removed = 2s0
1 e- removed = 2s1
1 e- removed = 2s22p0
Decreasing

33. e- 2e- 2e- e- 2e- e- e- Decreasing Decreasing + + + + + +
Beryllium (Z=4)
4 protons screened
by 2 e-
Boron (Z=5)
5 protons screened
by 2 e-
Lithium (Z=3)
3 protons screened
by 2 e-
Decreasing
Decreasing

34. Trends in the Periodic Table
Atomic Radii (Size)
Increasing
Increasing
First Ionization Energy
Decreasing
Decreasing

35. Electron Affinity F- Fluorine (Z=9) 2e- 2e- e- 8e- 7e- Cl-+ +
2e-
2e- e-
8e-
7e-
Cl-
Chlorine (Z=17) e- + +
2e-
2e-
8e-
8e-
7e-
8e-

36. Trends in the Periodic Table
First Ionization Energy
Decreasing
Decreasing
Decreasing
Electron Affinity

37. Predicting Stable Ions
Sodium (Z=11) + +
2e-
2e-
8e-
8e- e-
Na+
Cl-
Chlorine (Z=17) e- + +
2e-
2e-
8e-
8e-
7e-
8e-