Catalyst – September 4 + 24, 2010

1. Catalyst – September 4 + 24, 2010 • What is an ion? • What are the 2 types of ions? • Fill in the blanks: ___________ electrons are those that interact to form chemical ________s.

2. Today’s Agenda • Catalyst • Review of Friday • Octet Rule and Stable Ions • Properties of Ionic Compounds (tom) • Exit Question, Tests, and Progress Reports

3. Today’s Objectives • SWBAT use the octet rule to predict the stable ion an atom will form in a chemical bond. • SWBAT describe the properties of ionic compounds. (tomorrow)

4. Review: What is a compound? • A compound results from interaction between valence electrons of different atoms.

5. Review: Lewis Dot Structures Lewis Dot Structures only show the number of valence electrons in an atom. • Valence electrons are the only electrons involved in bonding • Valence electrons are the most important electrons

6. Review: Lewis Dot Sructures What do the Lewis Dot Structures have in common?!?!?

7. Review: Ions • An ion is an element that has gained or lost anelectron. Cation = positive ion (+) Anion = negative ion (-) + -

8. Formation of Negative Ions (ANIONS) • Imagine that electrons are pieces of poop • Is poop is flying into your yard (an atom’s energy levels) a positive or negative thing? • So…if poop lands in your yard, are you more positive or more negative? - So…NEGATIVE ions are formed when an atom GAINS one or more electrons!

9. Formation of Positive Ions (CATIONS) • Imagine that electrons are pieces of poop • Is poop in your yard (an atom’s energy levels) a positive or negative thing? • So…if you get rid of the poop in your yard, are you more positive or more negative? + So…POSITIVE ions are formed when an atom LOSES one or more electrons!

10. Practice Questions • If an atom gains an electron it will have a ___________ charge. • If an atom loses an electron it will have a ___________ charge. • If chlorine gains 3 electrons it will have a _______ charge. NEGATIVE POSITIVE 3-

11. Cl loses 4 Electrons What is the ion formed? Ions!

12. Cobalt gains 2 electrons What is the ion formed? Ions!

13. Si3- What happened… Gain or lose? How many? Ions!

14. Si3- Silicon gained 3 electrons How many total electrons does Si have now? Ions

15. Practice Problems – Write all down! • Write down the ion that will form for the following: • Sr gains 5 electrons • Phosphorous loses 1 electron • Then, determine how many TOTAL electrons each ion will have after gaining or losing

16. Practice Problems – Write all down! How many TOTAL electrons do the following ions have? • Cl2+ • Li2- • Xe3+ • O1- • Zn5-

17. Notes: Octet Rule • What is different about the valence shells of the elements on the Left and those on the Right? • The noble gases have full valence shells, the other atoms do not…

19. 8 Octet Rule 8 • Key Point #1: The octet rule says that atoms are most stable when they have 8 valence electrons. • Atoms can gain or lose electrons to become stable (happy)  • Atoms with 4 or more valence electrons will GAIN electrons to become stable (happy)  • Atoms with 3 or less valence electrons will LOSE electrons to be stable (happy)  8 8

20. Octet Rule - Examples • How many electrons will the following atoms gain or lose to become stable (happy)? How many TOTAL electrons will the atom then have? What is the STABLE ION? • F • O • N • H

21. Try the following on your own • How many electrons will the following atoms gain or lose to become stable (happy)? How many TOTAL electrons will the atom then have? What is the STABLE ION? • P • Kr • Ca • I • K

22. Classwork Complete Half-Sheet and leave in group folder. Then, start working on HW Worksheet 6.3

23. Exit Question • Anion = _______ charge, Cation = _______ charge • What is the STABLE ION that will form for Lithium? • Draw the LDS for the following elements: • Sulfur • Magnesium HOMEWORK: Worksheet 6.3 AND Unit 2 RESUME!