Do Now:

1. Do Now: decreases 1. Atomic radius ________ from left to right across a period and _________ down the group. 2. Circle the element with the larger atomic radius. Justify your choice citing the trend in a sentence. Sodium vs. Rubidium Rubidium because atomic radius increases down the group. 3. What effect explains the trend in atomic radius across a period, despite an increasing number of electrons? Effective Nuclear Charge (Zeff) increases

2. Periodic Trends Unit 3 Lesson 3 Trend 2: Ionization Energy andTrend 3: Electron Affinity

3. Objectives • SWBAT use the trends in Ionization Energy and Electron Affinity to predict which elements will lose electrons and which will gain them by the element’s position on the periodic table. • SWBAT to predict which elements will lose or gain electron based on the element’s position on the periodic table.

4. Agenda • Defining Ionization Energy • The Ionization Energy Trend by Group • Why the I. E. Group Trend? Atomic Radius • The Ionization Energy Trend by Period • Why the I. E. Period Trend? Atomic Radius • Defining Electron Affinity • The Electron Affinity Trend by Group • Why the E. A. Group Trend? Atomic Radius • The Electron Affinity Trend by Period • Why the E. A. Period Trend? Atomic Radius • Valence Shells, A Simpler Explanation • Independent Practice

5. Comparison • Ionization Energy – How likely is an atom to lose an electron. • Electron Affinity – How likely an atom is to gain an electron.

6. Trend 2: Ionization Energy (Definition) • How likely is an atom to lose an electron. • Ionization Energy is defined as the amount of energy required to remove an electron from an atom or ion.

7. Ionization Energy Trend by Group

8. Ionization Energy Trend by Group • Ionization Energy decreases down the group. • Atoms are more likely to lose an electron down the group.

9. Ionization Energy Trend by Group Reason • Sodium because I. E. decreases down the group. • I. E. decreases down the group so Argon (period 3) has a higher 1st I. E. than Xenon (period 5) Which has a higher 1st I. E.? • Sodium or Cesium • Boron or Gallium • Xenon or Argon • Lead or Carbon

10. Why the I.E. Group Trend? Atomic Radius • As atomic radius increase, the valence electrons get further from the nucleus and are more weakly held. • Hence it requires less energy to remove them. Atomic Radius Increases

11. Agenda • Defining Ionization Energy • The Ionization Energy Trend by Group • Why the I. E. Group Trend? Atomic Radius • The Ionization Energy Trend by Period • Why the I. E. Period Trend? Atomic Radius • Defining Electron Affinity • The Electron Affinity Trend by Group • Why the E. A. Group Trend? Atomic Radius • The Electron Affinity Trend by Period • Why the E. A. Period Trend? Atomic Radius • Valence Shells, A Simpler Explanation • Independent Practice

12. Ionization Energy Trend by Period • Ionization Energy ___________from left to right across the period. • Atoms are _____ likely to lose an electron. increases less

13. Ionization Energy Trend by Period Reason • Oxygen because I. E. increases across the period. • I. E. increases across the period so Si (group 13) has a higher 1st I. E. than Mg (group 2) Which has a higher 1st I. E.? • Oxygen or Carbon • Phosphorous or Argon • Hydrogen or Helium • Silicon or Magnesium

14. Why the I.E. Period Trend? Atomic Radius • As atomic radius decreases, the valence electrons get closer to the nucleus and are more tightly held. • Hence it requires more energy to remove them. Atomic Radius Increases

15. Summary of Trends 1-2 I. E. Increases Atomic Radius Decreases I. E. Decreases Atomic Radius Increases

16. Agenda • Defining Ionization Energy • The Ionization Energy Trend by Group • Why the I. E. Group Trend? Atomic Radius • The Ionization Energy Trend by Period • Why the I. E. Period Trend? Atomic Radius • Defining Electron Affinity • The Electron Affinity Trend by Group • Why the E. A. Group Trend? Atomic Radius • The Electron Affinity Trend by Period • Why the E. A. Period Trend? Atomic Radius • Valence Shells, A Simpler Explanation • Independent Practice

17. Trend 3: Electron Affinity (Definition) • Electron Affinity is defined as the energy change that occurs when a neutral atom gains an electron.

18. Electron Affinity Trend by Group ? • A positive energy change means that the resulting anion is more stable and that energy is released into the system.

19. Electron Affinity Trend by Group • Electron affinity decreasesdown the group. • Atoms are less likely to steal an electron down the group. E. A. decreases

20. Electron Affinity Trend by Group Reason • Sodium because E. A. decreases down the group. • E.A. decreases down the group so Argon (period 3) has a higher 1st E. A. than Xenon (period 5) Which has a higher 1st E. A.? • Sodium or Cesium • Boron or Gallium • Xenon or Argon • Lead or Carbon

21. Why the E.A. Group Trend? Atomic Radius • As atomic radius increase, the valence electrons get further from the nucleus and are more weakly held. • Hence atoms have a more difficult time stealing electrons. Atomic Radius Increases

22. Agenda • Defining Ionization Energy • The Ionization Energy Trend by Group • Why the I. E. Group Trend? Atomic Radius • The Ionization Energy Trend by Period • Why the I. E. Period Trend? Atomic Radius • Defining Electron Affinity • The Electron Affinity Trend by Group • Why the E. A. Group Trend? Atomic Radius • The Electron Affinity Trend by Period • Why the E. A. Period Trend? Atomic Radius • Valence Shells, A Simpler Explanation • Independent Practice

23. Electron Affinity Trend by Period • Electron affinity ___________from left to right across the period. • Atoms are _____ likely to gain an electron. increases more E. A. increases

24. Electron Affinity Trend by Period Reason • Oxygen because E. A. increases across the period. • E.A. increases across the period so Si (group 13) has a higher E.A. than Mg (group 2) Which has a higher 1st E. A.? • Oxygen or Carbon • Phosphorous or Argon • Hydrogen or Helium • Silicon or Magnesium

25. Why the E.A. Period Trend? Atomic Radius • As atomic radius decreases, the valence electrons get closer to the nucleus and are more tightly held. • Hence it requires less energy to gain an electron. Atomic Radius Increases

26. Summary of Trends 1-3 E. A. Increases I. E. Increases Atomic Radius Decreases E. A. Decreases I. E. Decreases Atomic Radius Increases

27. Agenda • Defining Ionization Energy • The Ionization Energy Trend by Group • Why the I. E. Group Trend? Atomic Radius • The Ionization Energy Trend by Period • Why the I. E. Period Trend? Atomic Radius • Defining Electron Affinity • The Electron Affinity Trend by Group • Why the E. A. Group Trend? Atomic Radius • The Electron Affinity Trend by Period • Why the E. A. Period Trend? Atomic Radius • Valence Shells, A Simpler Explanation • Independent Practice

28. Valence Electrons: A Simple Explanation • Atoms prefer full Valence Shells. • Which group has full Valence Shells? _________________________ Group 18: The Noble Gases

29. Valence Electrons: A Simple Explanation • Atoms will lose (____) or gain (____) electrons in order to acquire a full valence shell I.E. E.A. More likely to ____e- More likely to ____e- lose gain

30. Valence Electrons: A Simple Explanation

31. Independent Practice • Let’s see what you’ve learned.