1) The document discusses electron configurations and the order in which atomic orbitals are filled. It provides guidance on asking questions to determine the electron configuration for any element, including the period, number of shells, group, valence electrons, and occupied subshells. 2) The d and f subshells are described as "special" because they fill in a different order than other subshells and have unique occupation ranges from 1-10 electrons for d and 1-14 for f. 3) The order of filling for different subshells is specified, with s and p orbitals filling first before the d and f orbitals are occupied.

1. 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
8A
group # = # valence (outside) e-
d p
f
s
Row
=
# shells

2. 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?

3. 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

4. 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

5. 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
1s22s22p6 3p6
3s2 4s2 4p65s2
3d10 5p6 6s2
4d10 6p67s2
5d10
4f14
7p6
6d10
5f14

6. 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
8A
group # = # valence e-
d
f
3d
4d
5d
6d
4f
5f
Subshells d and f are “special”

7. 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?

8. 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 row #?
3. how many shells?
4. what is the group #?
5. how many valence electrons?
6. what subshell(s) does Li have?
7. what is the electron configuration?

9. 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?

10. 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