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

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

Ionization Energy (I.E.) The amount of energy required to remove an electron from a gaseous atom. Example: Li  Li e- Depends on: 1.Distance between electron and nucleus 2.Nuclear charge (# of protons)

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- Easier to remove e- = e- further away from nucleus = lower I.E. More difficult to remove e- = e- closer to nucleus = higher I.E.

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

1 st Ionization Energies for Elements in the First 6 Periods

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

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

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. 1 st Ionization Energy 2 nd Ionization Energy 3 rd Ionization Energy Sodium kJ 4,560 kJ Magnesium738.1 kJ1,450 kJ7,730 kJ

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

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