1. Ionization Energy What is “ionization energy”? Answer: the energy required to remove an electron from a gaseous atom This means that energy is required to form positive ions. Energy is released when a negative ion is formed.

2. Ionization Energy (continued) Examples: 1.Na + ionization energy → Na + + e - 2.Cl + e - → Cl - + energy 3.Positive ions don’t have special names, but negative ions have their endings changed to –ide. –Oxygen ion = oxide –Nitrogen ion = ?? –Chlorine ion = ???

3. Ionization Energy (continued) Some Practice for you. For the following elements, write the formula for its ion formation and energy absorbed or released, and name the ion: 1.Cesium 2.Magnesium 3.Aluminum 4.Carbon 5.Astatine 6.Oxygen 7.Bromine

4. Review & Look at the Trends Why do atoms gain or lose electrons? Answer: to obtain a full octet of electrons in its outer valence orbital (like the noble gases have) What is the oxidation number of calcium? Answer: +2 Is calcium a cation or an anion? As a rule, metals form cations (+ ions), and nonmetals form anions (- ions).

5. QUICK Assignment Study Guide Workbook: p.43 (10-17)