1. Chapter 19: Chemical Bonding “Isn’t It Ionic?”

2. Questions for Review

3. What atomic particle determines the chemical properties of an element? a. protons b. neutrons c. electrons d. morons

4. What atomic particle determines the chemical properties of an element? a. protons b. neutrons c. electrons d. morons

5. Which electrons determine an element’s chemical properties? a. electrons near the nucleus of the atom b. middle energy level(s) c. valence electrons

6. Which electrons determine an element’s chemical properties? a. electrons near the nucleus of the atom b. middle energy level(s) c. valence electrons

7. How many valence electrons do most atoms need to become chemically stable? a.1 b.4 c.8 d.10

8. How many valence electrons do most atoms need to become chemically stable? a.1 b.4 c.8 d.10

9.  Atoms are chemically stable (or resistant to change) when their valence shells are completely filled with electrons.  For most atoms, 8 electrons are needed to be chemically stable.

10. Why do the Noble Gases not form compounds easily?  The valence shells of the Noble gases are already completely filled with electrons.  All of the Noble Gases, with the exception of helium, have 8 valence electrons.  Helium has only two electrons.  Therefore, the first energy level is full, making it stable with its two valence electrons.

11. How are electrons in an atom represented? a. Bohr Models b. Lewis Dot Diagrams c. both of these

12. How are electrons in an atom represented? a. Bohr Models b. Lewis Dot Diagrams c. both of these

13. Bohr Model of the Atom Sodium atom Chlorine atom

14. How are valence electrons in an atom represented? a. Bohr Models b. Lewis Dot Diagrams c. both of these

15. How are valence electrons in an atom represented? a. Bohr Models b. Lewis Dot Diagrams c. both of these See http://www.ausetute.com.au/lewisstr.htmlhttp://www.ausetute.com.au/lewisstr.html

16. Lewis Dot Diagrams

17. Why do chemical bonds form?

18. Stability is achieved when the atoms…  have achieved a Noble Gas configuration (which have a complete set of valence electrons) (In other words, atoms are stable when they have bonded with other atoms to completely fill their outer-level electron shells).

19. Chapter 19: Types of Chemical Bonds 1.Ionic Bonds = usually metal + nonmetal 2. Covalent Bonds = nonmetal + nonmetal

20. What are ions? How do ions form?

21. Ion an atom that has gained or lost one or more electrons, therefore it has a positive or negative charge

22. Ionic Bond  Usually forms between a metal and a nonmetal  Is the force of electrostatic attraction between positively and negatively charged ions

24. Demonstration of Ionic Bonding

25. A transfer of electrons takes place  If an atom loses electrons it becomes ____ charged.  If an atom gains electrons, it becomes ____ charged.

26. A transfer of electrons takes place  If an atom loses electrons it becomes _positively_ charged.  If an atom gains electrons, it becomes _negatively_ charged.

27.  Metals tend to lose electrons, becoming a positive ion (cation).  Nonmetals tend to gain electrons & become negative ions (anion).

29. Classify the following compounds as covalent or ionic: 1.NaCl 2.CO 2 3.H 2 O 4.MgCl 2 5.C 4 H 10

30. Classify the following compounds as covalent or ionic: 1.NaCl (ionic) 2.CO 2 (covalent) 3.H 2 O (covalent) 4.MgCl 2 (ionic) 5.C 4 H 10 (covalent)

31. Ionic Charges are indicated by a Superscript  superscript -“written above”  Examples: Na +, Mg 2+, Cl -, O 2-

32. Chemical Formula Indicates the elements in a compound and the ratio of the atoms of those elements in one unit of the compound.

33. Chemical Formula Examples: NaCl; H 2 O The “2” in H 2 O is a subscript. Subscript (“written below”)indicates the number of atoms of an element in a unit of that compound.

34. What is the ratio of sodium to chlorine in NaCl? What is the ratio of hydrogen to oxygen in H 2 O?

35. What is the ratio of sodium to chlorine in NaCl? 1:1 What is the ratio of hydrogen to oxygen in H 2 O? 2:1

36. Writing Formulas for Binary Ionic Compounds Determine the oxidation number of each ion (the number of electrons an atom gains or loses) Oxidation numbers for the representative elements can be determined from its position on the periodic table. Oxidation Numbers for transition elements are determined from their negative ions.

37. Oxidation State  In chemistry, the oxidation state is an indicator of the degree of oxidation of an atom in a chemical compound.chemistryoxidationatomchemical compound  The formal oxidation state is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic. chargeionic  Oxidation states are typically represented by integers, which can be positive, negative, or zero. integers http://en.wikipedia.org/wiki/Oxidation_state

38. Oxidation State  In some cases the average oxidation state of an element is a fraction, such as 8/3 for iron in magnetite (Fe 3 O 4 ).magnetite  The increase in oxidation state of an atom through a chemical reaction is known as an oxidation; a decrease in oxidation state is known as a reduction. Such reactions involve the formal transfer of electrons, a net gain in electrons being a reduction and a net loss of electrons being an oxidation.reduction  For pure elements, the oxidation state is zero. http://en.wikipedia.org/wiki/Oxidation_state

39. Oxidation Numbers can be predicted from the element’s position on the periodic table.

40. Writing Formulas for Binary Ionic Compounds 1.Write the symbol of the positive ion first. 2.Write the symbol of the negative ion. 3.Add the superscripts. Is the sum zero? 4.If the sum does NOT equal zero, criss- cross the ionic charges.

41. Writing Names for Binary Ionic Compounds 1.Write the name of the positive ion first. 2.Write the root of the negative ion’s name. 3.Change the ending to -ide.

42. Use the ion cards to write formulas for and name binary ionic compounds 1.sodium and chlorine 2.calcium and chlorine 3.aluminum and chlorine

43. Na 1+ Cl 1- Formula: NaCl Name of compound: sodium chloride sodium ion chloride ion

44. Ca 2+ Cl 1- Formula: CaCl 2 Name: Calcium Chloride

45. Al 3+ Cl 1- Formula: AlCl 3 Name: Aluminum Chloride Cl 1-

46. Polyatomic Ions  A group of atoms that shares a common ionic charge.  Polyatomic ions must be memorized --- there’s no way around it!  See the chart of common ions.

47. Examples of some polyatomic ions:  Ammonium ion: NH 4 1+  Nitrate ion: NO 3 1-  Nitrite ion: NO 3 1-  Hydroxide ion: OH 1-  Sulfate ion: SO 4 2-  Carbonate ion: CO 3 2-  Phosphate ion: PO 4 3-

48. Using the Ion Cards with Polyatomic Ions Na 1+ NO 3 1- Sodium ionNitrate ion Chemical Name: sodium nitrate Chemical Formula: NaNO 3

49. NH 4 1+ Ammonium ion NH 4 1+ Ammonium ion SO 4 2- Sulfate ion Chemical Name: ammonium sulfate Chemical Formula: (NH 4 ) 2 SO 4

50. NH 4 1+ Ammonium ion NH 4 1+ Ammonium ion PO 4 3- Phosphate ion Chemical Name: ammonium phosphate Chemical Formula: (NH 4 ) 3 PO 4 NH 4 1+ Ammonium ion

51. Ca 2+ calcium ion NO 3 1- Nitrate ion NO 3 1- Nitrate ion Chemical Name: calcium nitrate Chemical Formula: Ca(NO 3 ) 2

52. Roman Numerals are used with elements that have more than one common oxidation number. (This includes most of the transition elements)

53. Examples:  CuBr 2 is named Copper (II) bromide  PbCl 2 is named Lead (II) chloride

54. EXCEPTIONS: Roman Numerals are NOT needed for silver, cadmium, and zinc:  These transition elements ALWAYS have the following oxidation numbers: Ag + Cd 2+, Zn 2+

55. Examples:  AgBr is named silver bromide, and NOT silver (I) bromide, because silver always has a 1+ oxidation number.  The same is true for compounds containing Cadmium or Zinc. (Cd and Zn are always 2+)

56. Some Special Ions: Copper (I) and (II) = Cu + and Cu 2+ Iron (II) and (III) = Fe 2+ and Fe 3+ Chromium (II) and (III) = Cr 2+ and Cr 3+ Lead (II) and (IV) = Pb 2+ and Pb 4+

57. Write names for: 1.FeS 2.CuCl 3. PbBr 4

58. Check your work: 1.Iron (II) sulfide 2.Copper (I) chloride 3.Lead (IV) bromide

59. Write formulas from the following names: 1.Lead (II) bromide 2.Chromium (II) sulfide 3.CuI copper (II) iodide

60. Check your work: 4.PbBr 2 5.CrS 6.CuI 2

61. Ionic Compounds  Result from the formation of ionic bonds.  Exist usually between a metal and a nonmetal  Are fun to name and write formulas for once you know the rules!