Chemical Bonding: Understanding Mixtures vs. Compounds

1. Warm Up 10/29 What is the difference between a mixture and a compound?

2. Lesson: Intro to Chemical Bonding

3. Chemical Bond – an attractive force between atoms that is strong enough to enable the group to act as a unit.

4. What makes atoms bond? Why do they “want” to bond?

5. Dating Game What do you look for in a soul mate?

6. Like people, atoms want to feel complete. They feel complete by fulfilling the Octet Rule.

7. Sodium Chlorine

8. Octet rule – atoms tend to react and bond so that they have an outer energy level filled with electrons. • They can do this by gaining or losing electrons. • Most atoms will have 8 valence electrons after they bond. • Some will have 2 valence electrons, like hydrogen, helium, lithium, berrylium and boron.

9. Oxygen shares an electron pair with two hydrogen atoms, so that all of them fulfill the octet rule.

10. Warm Up 10/30 What electric charge does an atom have if it gains an electron? What if it loses an electron?

11. Lesson: Ionic Bonding Sodium chloride

12. Ionic Bond – electrons are transfered, then the ions attract each other. General Rules: 1) 1 Metal + 1 Non-metal 2) Elements on left lose electrons (+), elements on right gain electrons (-).

13. Sodium gives an electron to chlorine, so that both of them fulfill the octet rule. . +1 -1 .

14. Magnesium Oxide: Magnesium Oxygen -2 +2

15. . . -1 + 2 -1

16. Practice – Left side! • Directions: Write the formula units for the following ionic compounds: • Sodium & oxygen • Barium & fluorine • Rubidium & iodine • Calcium & sulfate (poly) • Potassium & sulfite (poly) • Aluminum & oxygen

18. Polyatomic Ions • Ions made of more than one atom (molecules that are ions) • All are anions, except ammonium • Have special names • Sulfate • Hydroxide • Phosphate

19. Warm Up 10/31 Give an example of a homogeneous mixture and a heterogeneous mixture.

20. Warm Up 11/1 If you had two liquids that formed a homogeneous mixture, what method could you use to separate them?

21. Lesson: Naming Ionic Compounds

22. How to Name: • 1. Cation’s name remains unchanged • Change the end of the anion’s name to “ide” • (polyatomic ion names stay the same) • NaCl = • K O = • Al (CO ) = Sodium chloride Potassium oxide 2 Aluminum carbonate 2 3 3

23. Problem: Some elements have more than one form of cation! Examples: Fe and Fe We call them Iron (II) and Iron (III) Cu and Cu Call them Copper (I) and Copper (II) 2+ 3+ + 2+

24. Metals with Double Cations: • Ti Ti • Cr Cr • Fe Fe • Cu Cu • Au Au • SnSn • PbPb +2 +3 +2 +3 +2 +3 + +2 + +3 +2 +4 +2 +4

25. Use Reverse Swap & Drop! CuCl = Is it Copper (I) or Copper (II)? Fe O = Is it Iron (II) or Iron (III)? 2 2 3

26. What if the reverse ‘Drop and Cross’ method doesn’t work? Example: FeO

27. Practice: Left Side! Directions: Write the names of the following ionic compounds. • MgO • KBr • Na O • FeCl • CuBr 2 3 2

28. Warm Up 11/12 What is the difference between an ionic compound like salt (NaCl) and a water molecule (H 0)? 2

29. Lesson: Covalent Bonding

30. Old Ideas Compound = 2 atoms that are chemically bonded together. Noble gases don’t chemically react. Why? They have 8 valence electrons.

31. New Ideas Atoms want 8 valence electrons. That means they will have a full outer energy level. Octet rule – atoms react and bond so that they have an outer energy level filled with 8 electrons. (Some atoms only need 2)

32. Bonding • Covalent • Electrons shared • 2 nonmetals • Ionic • Electrons transferred • 1 metal + 1 nonmetal

33. What actually holds the atoms together? They are both attracted to the shared electron.

34. 2 Chlorine Atoms

35. Chlorine Molecule 1 Shared pair of Electrons

36. Methane

37. Naming Covalent Compounds • Rules: • Name of the first element remains the same (might need a prefix) • Name of the second element ends in “ide” (might need a prefix) Example: S C 3

38. Prefixes

39. Practice Naming = Phosphorus trichloride • PCl • CO • N O • S N 3 = Carbon dioxide 2 = Dinitrogen monoxide 2 = Tetrasulfur pentanitride 4 5

40. Practice Writing Formulas • Selenium hexafluoride • Xenon tetrafluoride • Dichlorine heptoxide • Arsenic trifluoride • = SeF 6 • = XeF 4 • = Cl O 2 7 • = AsF 3

41. Left Side Practice Write the Names: 1) Br O 2) S N 3) SCl 4) Se F Write the Formulas: 5) Chlorine dioxide 6) Selenium tetrafluoride 7) Dinitrogen trioxide 8) Tetraphosphorus pentasulfide 2 4 5 4 2 3

42. Warm Up 11/13 What is the electron configuration of sulfur?

43. Warm Up 12/9 Draw the lewis dot structure for NF 3

44. . . . . . . . . . . . . Trigonal Pyramidal . . . . . F N F . . . . . . . . . F

45. Ionic Covalent • 1 Metal + 1 Nonmetal • Electrons transferred (stolen) • Swap & Drop • 2 Nonmetals • Electrons shared • Prefixes Metallic

46. Ionic Characteristics • Forms crystal structures • High melting and boiling points • Conducts electricity when melted • Can dissolve in water CaF 2

48. Natural NaCl

49. Covalent Characteristics • Gases, liquids or solids (molecules) • Low melting and boiling points • Poor conductors of electricity • Usually not soluble in water

50. Metallic Bonding The valence electrons of metals move about freely, forming a “sea” of electrons.