1. Bohr Models – Selected Ans
Sodium [11]
Carbon [6]
Chlorine [17]
p+s = 11
p+s = 6
p+s = 17
e-s = 11
e-s = 6
e-s = 17
1st ring = 2 e-s
2nd ring = 8 e-s
2nd ring = 4 e-s
3rd ring = 1 e-s
3rd ring = 7 e-s

2. Electron Configuration
Unit 2 – Lecture 4

3. Background Information
Groups = vertical columns
Periods = horizontal rows

4. Describing Orbitals e-s exist in shells surrounding the nucleus
Lewis dot structures – show valence shell of e-s only
can be used to show bonding

5. Describing Orbitals – cont’d
Bohr Models – show basically same info but includes also the other levels used to figure out valence e-
further knowledge has shown that e-s actually move in a cloud, taking up more than just rings
model to the right is about 70 years out of date!!

6. Quantum Numbers Quantum #s – describe the “clouds” of e-s
First E Level = “s”
up to 2 e-s
Second E Level = “p”
up to 6 e-s
Third E Level = “d”
up to 10 e-s
…that’s as high as we’re going to go

7. Quantum Numbers – cont’d
1s(up to 2)
2s(up to 2)
Levels fill from lowest (s) to highest (d-for our purposes…)
2p(up to 6)
3s(up to 2)
3p(up to 6)
4s(up to 2)
3d(up to 10)
4p(up to 6)
***the 4th level “s” fills before the 3rd “d” level!!!!!

8. Quantum #s Examples Hydrogen –
# of e-s = [recall: atoms are neutral] = 1
e-s determine shells
will only fill part of the first “s” orbital
we note this as “ 1s1 ” meaning 1st s orbital w/ 1 e-

9. Quantum #s Examples Phosphorous –
# of e-s = [recall: atoms are neutral] = 15
e-s determine shells
15 e-s; fill from bottom up
notation:
1s2
2s2
2p6
3s2
3p3

10. Quantum #s Examples Manganese –
# of e-s = [recall: atoms are neutral] = 25
e-s determine shells
25 e-s; fill from bottom up
notation:
1s2
2s2
2p6
3s2
3p6
4s2
3d5

11. Quantum #s & Periodic Table
Period Indicates Quantum Numbers!!! Just count across the periods…