After today, you will be able to…

1. After today, you will be able to… • Explain what ionization energy is • Describe the ionization energy trend from the Periodic Table • Explain why it requires more energy to remove each subsequent electron after the first

2. Unit 4: The Periodic Trends Trends with Ionization Energy (I.E.)

3. Ionization Energy (I.E.) • The amount of energy required to remove an electron from a gaseous atom. Example: Li  Li+1 + 1e- • Depends on: • Distance between electron and nucleus • Nuclear charge (# of protons)

4. Group trend: I.E. decreases as you go down a group due to a greater # of energy levels Example: Ionization energy for elements in the same group: Lithium vs. Cesium e- e- Easier to remove e- = e- further away from nucleus = lower I.E. More difficult to remove e- = e- closer to nucleus = higher I.E.

5. Period trend: I.E. increases as you move across a period due to an increased nuclear charge Electrons are held more tightly because of more protons therefore more I.E. is required to remove an electron

6. 1st Ionization Energies for Elements in the First 6 Periods

7. It always requires more energy to remove a 2nd or 3rd electron because they are more attracted to a positive ion than to a neutral atom.

8. 1st I.E. - Energy required to remove the 1st electron. 2nd I.E. - Energy required to remove the 2nd electron. 3rd I.E. - Energy required to remove the 3rd electron. 1st I.E. < 2nd I.E. < 3rd I.E.

9. 4,560 kJ 495.9 kJ Sodium There is a very large increase of ionization energy whenever an electron is removed from an atom/ion that is isoelectronic with a noble gas. Magnesium 738.1 kJ 1,450 kJ 7,730 kJ

10. Summary: Ionization Energy Easy way to remember: THE UPSIDE-DOWN SNOWMAN Increases Decreases

11. Do now: Complete and Turn in “Exit Ticket” Then: Begin WS 3 (Homework)