1. Chapter 8 Notes, part I Writing Ionic Formulas

2. Compounds Up until now, we have only looked at single elements. There are only (to date) just over 100 elements, so how do we account for there being so many different types of stuff?

3. Compounds There are millions of different compounds—two or more elements that are combined chemically. The two types of compounds we will discuss in this chapter are ionic compounds and covalent compounds.

4. A compound is a pure substance made up of two or more elements that A compound is a pure substance made up of two or more elements that are chemically joined in definite proportions. Ex. Carbon dioxide is CO 2, while carbon monoxide (the poison) is CO. 2 oxygen atoms 1 oxygen atom

5. Compounds do not look or act like the elements that form them.

6. Sodium is a silvery metal that reacts violently with water Chlorine is a poisonous, green gas. Does salt share any of those properties?

7. Oxygen + Hydrogen -----> Water Hydrogen is explosive! Is water explosive?

8. Ionic Compounds Last chapter we discussed ions— elements that have a charge due to losing or gaining electrons. Ionic compounds are made of ions.

9. Ionic Compounds Metals tend to form ions by losing electrons, giving them an overall positive charge. These are called cations. Nonmetals tend to form ions by gaining electrons, giving them an overall negative charge. These are called anions.

10. Ionic Compounds An ionic compounds is formed from a cation and an anion, which means they are usually formed from a metal and a nonmetal.

11. IONIC Compounds Ionic compounds consist of two oppositely charged ions. Li +1 F -1 Positive ion – metal Negative ion - nonmetal 9p + 10n 0 3p + 4n 0 Li 0 F0F0 F -1 Li +1

12. Covalent compounds occur between two nonmetals. Both nonmetals share electrons 8p + 8n 0 6p + 6n 0 8p + 8n 0 Carbon dioxide

13. Atoms are stable, or resistant to change if their outer energy level is completely filled with electrons. 10p 10n NEON

14. Atoms of all the elements have from one to seven electrons in their outer energy level except the noble gases. 3p 4n 9p 10n

15. When atoms lose or gain Electrons they become ions. Na +1 Cl -1 Al +3 P -3 Mg +2 O -2 Single or Monoatomic ions

16. Ionic Compounds Anions and cations can also be made up of a group of elements bonded together that carry an overall charge. These groups of elements are called polyatomic ions.

17. Polyatomic ions - groups of 2 or more elements that have a charge PO 4 -3 SO 4 -2 NH 4 +1 CO 3 -2 NO 4 -1 NO 3 -1 SO 3 -2 ClO 3 -1 C 2 H 3 O 2 -1

18. Ionic Compounds Even though an ionic compound is made from charged particles, it is still electrically neutral. This means that its total charge is always EQUAL TO ZERO!!!

19. Ionic Compounds SIDENOTE: The smallest part of an ionic compound is called a formula unit—just like the smallest part of an element is called an atom.

20. Chemical Formulas A chemical formula is like the recipe of a compound—it tells you the type and number of each element in the compound.

21. Compounds are written as formulas. Compounds are written as formulas. Formula - a group of symbols, possibly with subscripts, showing the number and type of atoms forming the compound. Na 2 SO 4 Ba 3 (PO 4 ) 2

22. Formulas consist of a positive ion and a negative ion. Na +1 Cl -1 Al +3 P -3 Mg +2 O -2 NaClMgO AlP The positive ion always comes 1st

23. The positive ion is written first!!!!!!!! The positive ion is written first!!!!!!!! We read from left to right…. Metals are on the left. ( L EFT = L OSE e- = positively charged ions) Metals are first !!!!! Na +1 Cl -1

24. Nonmetals are on the right… and GAIN e- = negative ions Nonmetals are second!!!!! NaCl Na +1 Cl -1

25. Subscript - a small lowered number that shows number of atoms of each element in the compound. Ba 3 P 2 Ba P P

26. A subscript of (1) is NEVER written. Na 1 Cl 1 NO!!!

27. Oxidation number - the charge of an atom, indicating whether the atom has lost (+) or gained (-) electrons and how many electrons it lost or gained. Al Superscript +3

28. Oxidation Numbers GroupLose or gain electrons How manyOxidation Number 1Alose1+1

29. Oxidation Numbers GroupLose or gain electrons How manyOxidation Number 1Alose1+1 2Alose2+2

30. Oxidation Numbers GroupLose or gain electrons How manyOxidation Number 1Alose1+1 2Alose2+2 3Alose3+3

31. Oxidation Numbers GroupLose or gain electrons How manyOxidation Number 1Alose1+1 2Alose2+2 3Alose3+3 4ALose or gain4+4 or -4

32. Oxidation Numbers GroupLose or gain electrons How manyOxidation Number 1Alose1+1 2Alose2+2 3Alose3+3 4ALose or gain4+4 or -4 5Again5-3

33. Oxidation Numbers GroupLose or gain electrons How manyOxidation Number 1Alose1+1 2Alose2+2 3Alose3+3 4ALose or gain4+4 or -4 5Again3-3 6Again2-2

34. Oxidation Numbers GroupLose or gain electrons How manyOxidation Number 1Alose1+1 2Alose2+2 3Alose3+3 4ALose or gain4+4 or -4 5Again3-3 6Again2-2 7Again1

35. Oxidation Numbers GroupLose or gain electrons How manyOxidation Number 1Alose1+1 2Alose2+2 3Alose3+3 4ALose or gain4+4 or -4 5Again3-3 6Again2-2 7Again1 8Anone 0

36. The total charge on a compound must add up to ZERO. Ca CaO O O -2 Ca +2 +2 -2 = 0

37. IONIC COMPOUNDS Ionic compounds consist of a or Positive metal or ion positive polyatomic ion or Negative nonmetal or negative polyatomicion

38. Binary compounds are composed of only two elements. (Look for 2 capital letters!) Ex. NaCl sodium chloride Ex. Mg 3 N 2 magnesium nitride

39. Polyatomic compounds are composed of three or more composed of three or more elements and contain at elements and contain at least one polyatomic ion. (Look for 3 or more capital letters) NaC 2 H 3 O 2 1 234

40. Polyatomic ions Ex. Na ClO 3 sodium chlorate Ex. Ca 3 (PO 4 ) 2 calcium phosphate

41. A practical approach to determining if a metal is variable or non-variable.

42. VARIABLE If the metal is on the back of the periodic table with more than one oxidation number listed it is variable. EX: Cr= +2, +3, or +6 Fe= +2, or +3 Fe= +2, or +3 Look at the chart on the back of periodic table.

43. Look at the chart on the back of periodic table. NON VARIABLE If it is not on the back of the periodic table OR Only one choice of oxidation number listed. EX: Ag +1, Zn +2, or Ni +2 Then it is non variable

44. ROMAN NUMERALS Used when a metal has more than one potential oxidation number. The name of the metal must tell you the valence of the metal

45. Chromium chloride III The Roman numeral three tells you that the oxidation number of the metal is +3.

46. Chromium chloride VI The Roman numeral six tells you that the oxidation number of the metal is +6.

47. Writing and Naming Ionic Compounds

48. Writing Chemical Formulas 1) Write the symbol for the elements and their oxidation number, positive ion first (the metal). EX: For a compound of Magnesium and Chlorine Mg +2 Cl

49. Writing Chemical Formulas 2) Criss cross the numbers and write them as subscripts without the signs. Mg Cl +221

50. Writing Chemical Formulas 3) If there is a one charge, do not write it. Mg 1 Cl 2 Mg Cl 2

51. Writing Chemical Formulas 4) If you have subscripts that are multiples, reduce them down. PbO +4-242 2 1

52. Naming Ionic Compounds For ionic compounds where the metal always has the same oxidation number, 1) Name the metal. EX: BaBr 2 Barium

53. Naming Ionic Compounds For ionic compounds where the metal always has the same oxidation number, 2) Write the name of the non-metal, and change the end to –ide. Barium brom ine ide EX: BaBr 2

54. Naming Binary Non variable Compounds 1. Name the positive ion 2. Name the negative ion changing the ending to IDE. AlBr 3 AlBr 3 Aluminum bromide No Roman numeral is needed

55. -ides -ides N - Nitrogen--> Nitride O – Oxygen --> Oxide F - Fluorine--> Fluoride P - Phosphorus--> Phosphide S - Sulfur--> Sulfide Cl - Chlorine-->Chloride Br - Bromine -->Bromide I - Iodine--> Iodide

56. Naming Polyatomic Non variable Compounds 1. Name the positive ion 2. Name the negative ion changing the ending to -ate. AlPO 4 AlPO 4 Aluminum No Roman numeral is needed Phosphate

57. Naming Ionic Compounds If there is a polyatomic anion, then you do not change the ending: EX: Ca(NO 3 ) 2 Calcium nitrate

58. Name These: Na 2 O MgCl 2 Na 2 CO 3

59. Naming binary compounds of variable metals Determine the oxidation number of the variable metal using the crisscross method Cr 2 O 3 Cr + O - The oxidation number of the chromium is +3 The name is Chromium III oxide 32

60. Naming Ionic Compounds 3)If a positive ion (a metal) can have more than one oxidation number, you have to designate its charge in the name! We do this by putting the charge as a roman numeral in parenthesis between the positive and negative ion.

61. Naming Ionic Compounds Why do we need to do that? Name: Fe 2 O 3 FeO These both exist in nature, so we have to show which one we mean.

62. Naming Ionic Compounds Fe 2 O 3 Name it: Iron ox ygen ide ( ) III -2 If this is true, then what was iron to begin with? +3 Reverse criss cross to find the charge of the iron:

63. Naming Ionic Compounds Fe O Name it: Iron ox ygen ide ( ) II If this is not true, the numbers must have been reduced. +2-2

64. Naming Ionic Compounds Metals that don’t need parentheses: Group I, II and IIIA Zn, Cd (always +2) and Ag (always +1) Which means transition, inner transition and other metals do!

65. Naming polyatomic compounds of variable metals Determine the valence of the variable metal using the crisscross method Hg 2 SO 4 +- Hg + SO 4 - The oxidation number of the Mercury is +1 Mercury I sulfate 12

66. Naming Ionic Compounds Final flowchart of how to name: Name the positive ion. Does it need a roman numeral? If so, reverse criss cross, if not, ignore. Name the negative ion and: If a nonmetal end in -ide; if not, end normally

67. Name these: Na 2 S CuCl 2 K 2 SO 4 Pb(NO 3 ) 3

68. Finding formulas 1.Determine the charge of each side of the formula. Nonvariables: Aluminum oxide: Al +3 O- 2 Potassium Chloride K +1 Cl -1 Calcium nitrate Ca +2 NO 3 -1 2. Add the oxidation numbers together. +3-2 = +1 +1-1 = 0 +2-1 = +1

69. 2. Add the oxidation numbers together. Al +3 O -2 K +1 Cl -1 +3-2 = +1 +1-1 = 0 +3-2 = +1 +1-1 = 0 3. If the total = zero the formula is balanced with one ex: KCl ion each ex: KCl

70. If the total does not equal zero use the crisscross method to determine the number of ions needed for each side of the formula. +3-2 Al +3 O -2 Al O 32

71. If the total does not equal zero use the crisscross method to determine the number of ions needed for each side of the formula. +3-2 Al +3 SO 4 -2 Al SO 4 32 ()

72. Writing Chemical Formulas 5) If using polyatomic ions, put parentheses if there are more than one. CaNO 3 +221 ()

73. Writing Chemical Formulas Here’s an example of a polyatomic that doesn’t have parentheses. NaPO 4 +1-313

74. Practice These: Barium and chlorine Rubidium and nitrogen Lithium and phosphate Iron (III) and nitrate Manganese (IV) and sulfur BaCl 2 Rb 3 N Li 3 PO 4 Fe(NO 3 ) 3 MnS 2

75. Chapter 8 Notes: Part III Bonding in Metals

76. Metallic Bonds Metallic bonds consist of metal cations with a free-floating “sea of electrons” This explains many physical properties—why metals are good conductors, and why they are malleable and ductile

77. Malleablilty/Ductility Ductile – the ablity to be drawn into wires Malleable – the ablity to be hammered into shapes

78. Malleablilty/Ductility Metals display these characteristics because when subjected to pressure, cations can easily slide past one another (unlike ionic solids, which have very strong attractive and repulsive forces)

79. Alloys Most metals you use everyday are a mixture of two or more elements, for example brass, bronze or steel. These are called alloys.

80. Alloys The importance of alloys are that often they have superior properties than the elements they are made of.

81. Oxyanions An oxyanion is a polyatomic ion composed of an element, usually a nonmetal, bonded to one or more oxygen atoms. Many oxyaions contain the same nonmetal and have the same charges but differ in the number of oxygen atoms.

82. These ions are easily named using the following conventions. The ion with more oxygen atoms is named using the root of the nonmetal plus the suffix-ate. The ion with fewer oxygen atoms is named using the root of the nonmetal plus the suffix-ite.

83. Halogens form four oxyanions The ion with the greatest number of oxygen atoms is named using the prefix per-, the root of the nonmetal, and the suffix –ate. The ion with one less oxygen atom is named with the root of the nonmetal and the suffix –ate. The ion two fewer oxygen atoms is named using the root of the nonmetal plus the suffix –ite.

84. The ion with three fewer oxygen atoms is named using the prefix hypo-, the root of the nonmetal, and the suffix – ite.