1. Electron Configurations
Atomic Structure II
Electron Configurations
Barbara A. Gage PGCC CHM 1010

2. Atomic Orbitals Each electron is assigned to:
Primary energy level (shell), n
Orbital type in the shell (s,p,d,f)
Specific orbital of the type
Because of repulsion considerations only 2 electrons can occupy any orbital (spinning in opposite directions)
Barbara A. Gage PGCC CHM 1010

3. Atomic Shells and Orbitals
Shell (n)
# s orbitals
# p orbitals
# d orbitals
# f orbitals
Total e- 1 2 3 8 5 18 4 7 32 50
Barbara A. Gage PGCC CHM 1010

4. This diagram shows the energy levels of the atomic orbitals. Electrons
fill orbitals
from bottom
to top of
the diagram.
Barbara A. Gage PGCC CHM 1010

5. A vertical orbital diagram for the Li ground state.
no color-empty
light - half-filled
The electron configuration is
written as:
1s22s1
# electrons in orbital
orbital
dark - filled, spin-paired
shell
Barbara A. Gage PGCC CHM 1010

6. Barbara A. Gage PGCC CHM 1010

7. Barbara A. Gage PGCC CHM 1010

8. like this to determine the electron configuration.
You can use a chart
like this to determine the
electron configuration.
(But there is an easier
way.)
Barbara A. Gage PGCC CHM 1010

9. A periodic table of partial ground-state electron configurations.
Barbara A. Gage PGCC CHM 1010

10. Determining Electron Configuration
PROBLEM:
Using the periodic table on the inside cover of the text (not Figure 8.12 or Table 8.4), give the full and condensed electrons configurations, partial orbital diagrams showing valence electrons, and number of inner electrons for the following elements:
(a) potassium (K: Z = 19)
(b) molybdenum (Mo: Z = 42)
(c) lead (Pb: Z = 82)
Use the atomic number for the number of electrons and the periodic table for the order of filling for electron orbitals. Condensed configurations consist of the preceding noble gas and outer electrons.
SOLUTION:
(a) for K (Z = 19)
condensed configuration
partial orbital diagram
full configuration
1s22s22p63s23p64s1
[Ar] 4s1
There are 18 inner electrons.
4s1 3d 4p
Barbara A. Gage PGCC CHM 1010

11. condensed configuration partial orbital diagram full configuration
(b) for Mo (Z = 42)
condensed configuration
partial orbital diagram
full configuration
1s22s22p63s23p64s23d104p65s14d5
[Kr] 5s14d5
There are 36 inner electrons and 6 valence electrons.
5s1
4d5 5p
(c) for Pb (Z = 82)
1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p2
condensed configuration
partial orbital diagram
full configuration
[Xe] 6s24f145d106p2
There are 78 inner electrons and 4 valence electrons.
6s2
6p2
Barbara A. Gage PGCC CHM 1010

12. Configuration for Ions
What is the electron configuration for Na+?
Na = 1s22s22p63s1
Na+ = 1s22s22p63s1
What is the electron configuration for Se2-?
Se = 1s22s22p63s23p64s23d104p4
Se2- = 1s22s22p63s23p64s23d104p6
Barbara A. Gage PGCC CHM 1010

13. Configuration for Ions
Transitions metals have a twist…
Fe = 1s22s22p63s23p64s23d6
Fe2+ = 1s22s22p63s23p64s23d6
Fe3+ = 1s22s22p63s23p64s23d5
Barbara A. Gage PGCC CHM 1010