1. Ions

2. Ion Charged atom of an element Formed from gaining or losing electrons
Charge of ion = oxidation number

3. Anion Formed from an element gaining electrons Negatively charged
Usually nonmetals form anions

4. Cation Formed from losing electrons Positively charged
Usually metals form cations

5. Why do elements form ions?
Elements want to be like noble gases
full set of valence electrons = 8
Stable
Unreactive

6. How many electrons will each need to gain or lose to become an ion?

7. How many electrons will each need to gain or lose to become an ion?Na Mg

8. Elements and Oxidation Numbers
Elements in the same group (Main group elements 1-2 and 13-18) have the same oxidation numbers
Group 1 = +1
Group 2 = +2
Group 13 = +3
Group 14 = +4 or -4
Group 15 = -3
Group 16 = -2
Group 17 = -1
Group 18 = 0

9. Ion Lewis Dot Diagrams Always: Add bracket around element symbol
Add charge as superscript on right side
If loses electrons, no valence electrons shown around symbol
If gains electrons, there should be 8 valence electrons shown (except for H)

10. Na , P , O , Cl, Mg , K , H Practice Question 1
Which of the following elements are cations as ions?
Na , P , O , Cl, Mg , K , H

11. Practice Question 2
What is the charge of Aluminum as an ion and how many electrons will it have?

12. Practice Question 3
Draw the lewis dot diagram for the element Oxygen and the ion Oxygen.

13. Practice Question 4
What group on the periodic table will have a charge of +3?