•Elements
•Valence Electrons
1
1
2
H
He
Hydrogen
1
Helium
4
2
74
W
Tungsten
183.84
To find # of Neutrons: Atomic Mass (rounded) – Atomic # = NEUTRONS
184
–
74 =
110
6
2
4
8
C
O
Carbon
12
Oxygen
16
2
6
Valence Electrons
(8 is Great)
•Electrons in outer level
•Most important electrons
•Determine if atoms will chemically react
1
H
Hydrogen
1 Valence
Electron
2
4
C
Carbon
4 Valence
Electrons
10
2
8
11
Ne
Na
Neon
20
Sodium
23
2
8
1
2
8
Ne
Neon
8 Valence
Electrons
No
Valence
Electrons
missing
Stable and
nonreactive
2
8
1
Na
Sodium
1 Valence
Electron
7 Valence
Electrons
missing
Unstable
and
reactive
16
Red circle shows how many valence electrons there are in each column. Can only be
between 1 to 8. Example: Carbon in column 14 has 4 valence electrons and Oxygen in
column 16 has 6 and Hydrogen in column 1 has 1. (This does not work for 3-12)