The document discusses electronic configuration, which is the distribution of electrons in atomic or molecular orbitals. It explains that electrons are arranged in shells and subshells around the nucleus, with the subshells labeled s, p, d, and f. The order that electron subshells are filled is provided, with exceptions to a simple ordering. Examples of writing the electronic configuration of different elements are given by asking a series of questions.

1. What is Electronic
Configuration?
In atomic physics and quantum chemistry,
the electron configuration is the distribution of
electrons of an atom or molecule (or other physical
structure) in atomic or molecular orbitals.

2. How electrons are arranged
around the nucleus of an atom?
• The number of protons in the atom of
an element determines its place in the
Periodic Table.
• The number of electrons in an atom is
the same as the number of protons.
These electrons are arranged in shells or
'energy levels' around the nucleus.

3. What are the Subshells?
• A subshell is a subdivision of electron
shells or energy levels separated by
electron orbitals.
• Subshells are labelled s, p, d, and f in an
electron configuration. Examples: The first
electron shell is the 1s subshell. The
second shell of electrons contains the 2s
and 2p subshells.

4. 1
2
3
4
5
6
7
6
7
1A
2A
3B 4B 5B 6B 7B 8B 8B 8B 1B 2B
3A 4A 5A 6A 7A
8Agroup # = # valence (outside) e-
d p
f
s
Row
=
# shells

5. • The block names (s, p, d, f and g) are
derived from the spectroscopic notation
for the associated atomic orbitals
: sharp, principal, diffuse and fundamental

6. Electron Configuration
1s1
row #
shell #
possibilities are 1-7
7 rows
subshell
possibilities are
s, p, d, or f
4 subshells
group #
# valence e-
possibilities are:
s: 1 or 2
p: 1-6
d: 1-10
f: 1-14
Total e- should equal
Atomic #

7. 1
2
3
4
5
6
7
6
7
period#=#e-shells
1A
2A
3B 4B 5B 6B 7B 8B 8B 8B 1B 2B
3A 4A 5A 6A 7A
8Agroup # = # valence e-
d
f
3d
4d
5d
6d
4f
5f
Subshells d and f are “special”

8. Order of Electron Subshell Filling:
It does not go “in order”
1s2
2s2
2p6
3p6
4p6
5p6
6p6
7p6
3s2
4s2
5s2
6s2
7s2
3d10
4d10
5d10
6d10
4f14
5f14
1s2
2s2
2p6
3p6
3s2
4s2
4p6
5s2
3d10
5p6
6s2
4d10
6p6
7s2
5d10
4f14
7p6
6d105f14

9. Electron Configuration
1s1
row #
shell #
possibilities are 1-7
7 rows
subshell
possibilities are
s, p, d, or f
4 subshells
group #
# valence e-
possibilities are:
s: 1 or 2
p: 1-6
d: 1-10
f: 1-14
Total e- should equal
Atomic #
What element has an electron configuration of 1s1
?

10. Practice:
Ask these questions every time you have to write an
electron configuration
• Lithium:
1. find the element on the periodic table
2. what is the period number?
3. how many shells?
4. what is the group number?
5. how many valence electrons?
6. what subshell(s) does Li have?
7. what is the electron configuration?
atomic # = 3
2
2
1
1
s
1s2
2s1

11. Practice:
Ask these questions every time you have to write an
electron configuration
• Boron:
1. find the element on the periodic table
2. what is the row #?
3. how many shells?
4. what is the group #?
5. how many valence electrons?
6. what subshell(s) does B have?
7. what is the electron configuration?
atomic # = 5
2
2
3
3
p
1s2
2s2
2p1

12. Practice:
Ask these questions every time you have to write an
electron configuration
• Sr:
1. find the element on the periodic table
2. what is the row #?
3. how many shells?
4. what is the group #?
5. how many valence electrons?
6. what subshell(s) does Sr have?
7. what is the electron configuration?

13. Practice:
Ask these questions every time you have to write an
electron configuration
• N:
1. find the element on the periodic table
2. what is the row #?
3. how many shells?
4. what is the group #?
5. how many valence electrons?
6. what subshell(s) does N have?
7. what is the electron configuration?

14. Practice:
Ask these questions every time you have to write an
electron configuration
• Xe:
1. find the element on the periodic table
2. what is the row #?
3. how many shells?
4. what is the group #?
5. how many valence electrons?
6. what subshell(s) does Xe have?
7. what is the electron configuration?

16. Find the electronic configuration
of the ff:
1. Chlorine 4.Gallium
2. Krypton 5.Carbon
3. Lead
Using abbreviated electronic configuration:
1. Radon 4. Au
2. Francium 5. Copernicium
3. Nickel