1. Ions

2. Valence Shell
The outer ring of an atom filled with valence electrons

3. Octet Rule
Atoms are most stable when they have a full octet, or 8 valence electrons
Some atoms are exceptions – they are most stable with only 2 electrons (H, He, Li, Be, B)
Noble gases are all stable

4. Anions
Some atoms GAIN electrons to become stable
Negative charge

5. Anion Charge If chlorine gains an electron… P: 17+ E: 18-
Overall charge: -1

6. Cations
Some atoms LOSE electrons to become stable
Positive charge

7. Cation Charge If sodium loses an electron… P: 11+ E: 10-
Overall charge: +1

8. Bohr Model K Mg O F Ne Complete the following Bohr models.
Determine if the element needs to lose or gain electrons to become stable
(remember the levels!)
K Mg O F Ne

9. Patterns with valence electrons
What patterns do you notice based on your Bohr models?
The number of valence electrons matches the group number

10. Oxidation Number
The number of electrons needed to gain or lose for stability equals the oxidation number, or charge
Also a pattern by group
Label these representative groups:
Group 1: +1 Group 5: -3
Group 2: +2 Group 6: -2
Group 3: +3 Group 7: -1
Group 4: none Group 8: none

11. Ion P, N, E Symbol Protons Neutrons Electrons Charge K+1 19 20 18 +1
Be+2
Al+3
P-3
S-2
I-1 Xe

12. Lewis Dot Structures Used to represent the number of valence electrons
Can be used later in symbolizing chemical bonds between atoms

13. Checkpoint Why do atoms gain or lose valence electrons?
Describe the change in an atom that has a +3 charge. Why is it positive? What does the “3” mean?
When atoms gain or lose electrons, where do they go?
Define the octet rule.
Describe the patterns seen on the periodic table related to electrons.