1. A n io n – negatively charged ion (more electrons than protons) Ex:  Fluorine has 9 e - and is reactive (7 e- in valence shell)  Adding one e - makes fluorine less reactive because it now has a full valence shell  Fluorine ion written as F -  It is not neon (Ne has 8 e - like the F - ion)  It is not fluorine ….it is a fluorine ion!

2. Finding the amount of electrons in an ion Reason it out!! Or……. To find the e amount in an atom, subtract the charge number from the number of p (atomic number) Ex: Li + protons: 3 neutrons: 4 electrons: 3 – (+1) = 2

3. Ex: 35 Cl – protons: 17 neutrons: 18 electrons: 17 – (-1) = 18

4. Ex: O 2 - protons: 8 neutrons: 8 electrons: 8 – (-2) = 10

5. Ex: p = 20 n = 20 e = 18 Answer: 20 Ca 2+ 40

6. Ex: p = 16 n = 16 e = 18 Answer: 16 S 2- 32

7. Naming a Cation: uses the name of the parent atom Ex: Na + is called Sodium ion Mg 2+ is called a magnesium ion (charge of +2)

8. Naming a Anion: use the root name of the atom and change the ending to have the suffix “ -ide” Ex: F - is called Fluoride ion I - is called an Iodide ion O 2- is called an oxide ion (charge of -2)