Catalyst

1. Catalyst • What is the average percent correct needed to get a 3 on the AP Chemistry Exam? • What is the average percent correct needed to get a 4 on the AP Chemistry Exam? • What is the average percent correct needed to get a 5 on the AP Chemistry Exam? • Get your exam from Mr. Lance when completed and fill out the reflection sheet

2. Nothing in the world is worth having or worth doing unless it means effort, pain, and difficulty…I have never in my life envied a human being who led an easy life. -Theodore Roosevelt

3. Average % Correct for a 3 on the AP Chem Exam ~33% Overall

4. Average % Correct for a 4 on the AP Chem Exam ~48% Overall

5. Average % Correct for a 5 on the AP Chem Exam ~62% Overall

6. Ask Yourself… Have you done whatever It takes to succeed?

7. Unit 1 Test

8. Thoughts on Exam 1 • Naming Compounds – Homework for the weekend • Calculator training after school today. You all need to attend…way too many calculator errors were seen • Saturday school in the near future! OPTIONAL but we all need it • Don’t know the answer? Try to get something on the paper! • Units? Units? Where for ought thou units? • Homework…NOT OPTIONAL • Change in homework policy

12. Lecture 2.1 – Ionic Bonding and Lewis Structures

13. Today’s Learning Targets • LT 2.2 – I can explain how Coulomb’s Law dictates the relationship between cations and anions in ionic bonds. Furthermore, I can use Coulomb’s Law to compare lattice energies experienced in ionic compounds. • LT. 2.3 – I can draw simple and complex Lewis Structures and determine the formal charge of elements in these structures. Additionally, I can discuss and draw structures that appear to “violate” the Octet Rule.

14. Analyze the Data • With your table, complete the handout • Make sure you are able to justify your reasoning for every question.

15. Ionic Bonding • Ionic Bond – Bond formed through the transfer of electrons. • Formed between a metal and a non-metal

16. Ionic Bond Formation

17. Coulomb’s Law • The force felt by two charged objects is directly related to the size of the charge and inversely related to the distance between the charges.

18. Lattice Energies • If we examine the reaction of two elements, the transfer of electrons should not happen. • The transfer happens is because of the attraction between cations and anions • Lattice Energy – The energy required to separate a mole of solid ionic compound to its gaseous form.

20. Coulomb’s Law and Lattice Energies • The size of a lattice energy depends on 1. The size of the charge 2. The distance between the charges • Therefore, smaller ions and larger charges lead to higher lattice energies!

21. Covalent Bonding • Covalent Bonding – Bonds that form when two or more elements share electrons • Covalent bonds usually are between non – metals

22. Lewis Structures • Draw the Lewis structure for HCN

23. Lewis Structures • Atoms form single, double, and triple bonds. • Single Bond = 2 shared electrons • Double Bond = 4 shared electrons • Triple Bond = 6 shared electrons • As you add more bonds, the length of the bonds decreases • Therefore, single bonds are the longest and triple bonds are the shortest

24. Old Way of Drawing Lewis Structures • Our old way of drawing Lewis structures works for: H, C, N, O, and F. • Every other element does not work for using this old system because they can violate the Octet Rule

25. Exceptions to the Octet Rule • While the Octet Rule works for many compounds, there are exceptions. • Most elements can demonstrate the exceptions except hydrogen, carbon, nitrogen, oxygen, and fluorine

26. Exception 1: Less than an Octet of Valence Electrons • Seen in beryllium (Be) and boron (B) • These elements will form bonds whereby they have less than a full Octet in order to satisfy the other elements need for 8 electrons

27. Exception 2: More than an Octet of Valence Electrons • The most common exception to the Octet Rule • Expanded Octet occurs for the central atom. • Hypervalent – Molecules that have an expanded octet • Form for 3rd period and below elements

28. Drawing Lewis Structures: SWOOP! • Sum all of the valence electrons • Write out symbols with central atom able to form the most bonds • Outer Octets should be completed first • Place leftover electrons on the central atom by using lone pairs and/or bonds

29. Class Example • Draw the Lewis structure for PO43-

30. Table Talk • Draw the Lewis structure for ClO2-

31. You Be The Teacher: Lewis Structure Corrections • It’s 10 years in the future and you are teaching your own AP Chemistry course (since we all know that is what you all want to do after college) • You give a quiz on Lewis Structures. Correct this struggling student’s paper and provide comments

32. Formal Charges • Many compounds have more than 1 possible Lewis structure. • Formal charges tells us the “right” Lewis structure. • Formal Charge – The charge an element would have if all electrons were shared equally. • The “best” structure has: 1. Atoms that have formal charges closest to 0 2. Highest negative charge on the most electronegative atom

33. Calculating Formal Charges • To calculate formal charge:

34. Class Example • Draw NCS–, calculate its formal charge and pick the “best” Lewis structure.

35. Table Talk • Draw the Lewis structure for PF3 and label the formal charge of all atoms

36. Class Example • Draw the Lewis structure for BCl3

37. Table Talk • Draw the Lewis structure for ICl4 –

38. White Board Practice • Answer the following questions on your white board • Don’t put up the boards until I tell you too!

39. Question 1 • Label the formal charges on the molecule below

40. Question 2 • Label the formal charges on the compound below

41. Question 3 • Label the formal charges on the compound below

42. Question 4 • Draw the Bohr structure for BI3

43. Question 5 • Draw the Bohr structure for SI5

44. Question 6 • Draw the Lewis structure for XeF6

46. Closing Time • Naming Practice • Test Error Analysis Worksheet • Post – Lab Questions for Lab 3 due Tuesday. NO LONGER A LAB REPORT! Your Welcome 