1. Chemical Nomenclature

2. Octet Rule n Atoms tend to achieve electron configuration of Noble Gases n Octet = Eight n Noble Gases have eight electrons in their highest energy level n General Equation for Noble Gases is S 2 P 6

3. n Atoms of Metallic Elements tend to lose valence electron/s, leaving an octet in the next lowest energy level n Atoms of a Non-Metallic Element tend to gain a valence electron/s to achieve an Octet n There are EXCEPTIONS to the Octet Rule

4. © 2009, Prentice-Hall, Inc. Diatomic Molecules These eight elements occur naturally as molecules containing two atoms. Astatine is considered a diatomic

5. 2-5 Elements that exist as Diatomic Molecules n Most elements, except for the noble gases, do not exist as single atoms. n The halogens, along with hydrogen, nitrogen, and oxygen, exist naturally as diatomic molecules when in their element form (not as compounds). Figure 2.22 H 2 F 2 Cl 2 Br 2 I 2 N 2 O 2

6. Ions n Atoms or groups of atoms with a charge n Cations- positive ions - get by losing electrons(s) n Anions- negative ions - get by gaining electron(s) n Ionic bonding- held together by the opposite charges n Ionic solids are called salts

7. 2-7 Ions n Ions differ from atoms in that they have a charge; the number of electrons is either greater than, or less than, the number of protons. n Cations are positively charged. They have fewer electrons than in the neutral atom. n Anions are negatively charged. They have more electrons than in the neutral atom.

8. 2-8 Ions and the Periodic Table n The noble gases are the most stable (least reactive) elements on the periodic table. –Their stability is associated with the number of electrons they contain. n Many atoms in the main-group elements gain or lose electrons to obtain the same number of electrons as the nearest noble gas. »Metals tend to lose electrons, and therefore become cations. »Nonmetals tend to gain electrons, thereby becoming anions.

9. n Even though atoms and cations have the same name, there are many chemical differences between metals and their cations. n Example: n Na Metal; reacts explosively in water n Na Cation; quite unreactive

10. Cations l Positive ions. l Formed by losing electrons. l More protons than electrons. l Metals form cations. K +1 Has lost one electron Ca +2 Has lost two electrons

11. 2-11 Formation of Mg 2+ Cation Figure 2.14

12. Anion n A negative ion. n Has gained electrons. n Non metals can gain electrons. n Charge is written as a super script on the right. F -1 Has gained one electron O -2 Has gained two electrons

13. 2-13 Formation of N 3  Anion Figure 2.14

14. Charges on ions n For most of the Group A elements, the Periodic Table can tell what kind of ion they will form from their location. n Elements in the same group have similar properties. n Including the charge when they are ions.

15. n Monatomic Ions- consist of a single atom with a positive or negative charge resulting from the loss or gain of one or more valence electrons n Groups 1a, 2a, and 3a lose electrons and form cations n Aluminum is the only common group 3a element to lose electrons and form a cation

16. 3-16 Common Monatomic Ions Figure 3.12

17. n Non-metals tend to gain electrons and form an anion. n Groups 5a, 6a, and 7a form anions n In group 5a, there are three non-metals which form anions n N 3-, P 3-, & As 3-

18. n Majority of elements in 4a & 0 do not form ions n Group 0 rarely forms compounds n Ordinarily, two non-metals from group 4a, C & Si are found in molecular compounds

19. +1+2-2-3

20. Laws n Conservation of Mass n Law of Definite Proportion- compounds have a constant composition by mass. n They react in specific ratios by mass. n Multiple Proportions- When two elements form more than one compound, the ratios of the masses of the second element that combine with one gram of the first can be reduced to small whole numbers.

21. © 2009, Prentice-Hall, Inc. Law of Constant Composition Joseph Proust (1754–1826) n This is also known as the law of definite proportions. n It states that the elemental composition of a pure substance never varies.

22. © 2009, Prentice-Hall, Inc. Law of Conservation of Mass The total mass of substances present at the end of a chemical process is the same as the mass of substances present before the process took place.

23. Compounds n Follow the Law of Definite Proportion. n Have a constant composition. n Have to add the same number of atoms every time. n Two types.

24. 3-24 n NaCl is an ionic compound n CO 2 is a molecular compound n O 2 is a molecular element Figure 3.7

25. Molecular Compounds Molecular compounds n Made of molecules. n Made by joining nonmetal atoms together into molecules.

26. Ionic Compound Ionic Compounds n Made of cations and anions. n Metals and nonmetals. n The electrons lost by the cation are gained by the anion. n The cation and anions surround each other. n Smallest piece is a FORMULA UNIT.

27. 3-27 Ionic Compounds Figure 3.8

28. 3-28 Ionic Compounds Figure 3.18

29. Formula Unit n Formula Unit- lowest whole-number ratio of the ions in the compound n Example n Na + Cl - n Ratio is 1:1 n The formula unit is NaCl

30. Formula Unit n The smallest whole number ratio of atoms in an ionic compound. n Ions surround each other so you can’t say which is hooked to which.

31. Two Types of Compounds Smallest piece Melting Point State Types of elements Formula UnitMolecule Metal and Nonmetal Nonmetals solid liquid or gas High >300ºCLow <300ºC IonicMolecular

32. 3-32 Ionic and Molecular Compounds

33. 3-33 Activity: Identifying Ionic and Molecular Compounds Identify each compound as ionic or molecular. n CCl 4 n CaF 2 n SF 6 n CuCO 3 n H 2 O

34. © 2009, Prentice-Hall, Inc. Types of Formulas n Empirical formulas give the lowest whole- number ratio of atoms of each element in a compound. n Molecular formulas give the exact number of atoms of each element in a compound.

35. Writing Formulas n Two sets of rules, ionic and covalent n To decide which to use, decide what the first word is. n If is a metal or polyatomic use ionic. n If it is a non-metal use covalent

36. © 2009, Prentice-Hall, Inc. Writing Formulas n Because compounds are electrically neutral, one can determine the formula of a compound this way: –The charge on the cation becomes the subscript on the anion. –The charge on the anion becomes the subscript on the cation. –If these subscripts are not in the lowest whole-number ratio, divide them by the greatest common factor.

37. Ionic Formulas n Charges must add up to zero n get charges from table, name of metal ion, or memorized from the list n use parenthesis to indicate multiple polyatomics

38. Ionic Formulas n Sodium nitride n sodium- Na is always +1 n nitride - ide tells you it comes from the table n nitride is N -3

39. Ionic Formulas n Sodium nitride n sodium- Na is always +1 n nitride - ide tells you it comes from the table n nitride is N -3 n doesn’t add up to zero Na +1 N -3

40. Ionic Formulas n Sodium nitride n sodium- Na is always +1 n nitride - ide tells you it comes from the table n nitride is N -3 n doesn’t add up to zero n Need 3 Na Na +1 N -3 Na 3 N

41. Writing Formulas n Write the formula for calcium chloride. n Calcium is Ca +2 n Chloride is Cl -1 n Ca +2 Cl -1 would have a +1 charge. n Need another Cl -1 n Ca +2 Cl 2 -1

42. Crisscross n Switch the numerical value of the charges Ba 2+ N 3- 2 3 Ba 3 N2N2 Reduce ratio if possible

43. Polyatomic Ions n Polyatomic Ion- Tightly bound groups of atoms that behave as a unit and carry a charge n Unlike monatomic ions; Sulfate anion is composed of 1 Sulfur atom and 4 oxygen atoms n These five atoms form a Sulfate Anion n It has a –2 charge an is written SO 4 2-

44. 3-44 Polyatomic Ions n A polyatomic ion consists of a group of atoms with an overall net charge. n These two are also called oxoanions because they contain oxygen attached to some other element. n The most common polyatomic cation is NH 4 +. Figure 3.14

45. 3-45 Patterns for Polyatomic Ions Figure 3.17

46. n Polyatomic anions either end in ITE or ATE n Out of the two similar polyatomic ions, the polyatomic with less Oxygens ends in ite n Example: n Sulfite and Sulfate n Sulfite; SO 3 2- n Sulfate; SO 4 2-

47. n There are three exceptions to the Polyatomic Rule n 1) Ammonium NH 4 + ---- The only positive polyatomic ion n 2) Cyanide CN - ---- Ends in IDE n 3) Hydroxide OH - --- Ends in IDE

48. Write the formulas for these n Lithium sulfide n tin (II) oxide n tin (IV) oxide n Magnesium fluoride n Copper (II) sulfate n Iron (III) phosphide n gallium nitrate n Iron (III) sulfide

49. Ionic Compounds n Sodium sulfite n calcium iodide n Lead (II) oxide n Lead (IV) oxide n Mercury (I) sulfide n Barium chromate n Aluminum hydrogen sulfate n Cerium (IV) nitrite

50. Write the formulas for these n Ammonium chloride n ammonium sulfide n barium nitrate

51. Naming compounds n Two types n Ionic - metal and non metal or polyatomics n Covalent- we will just learn the rules for 2 non-metals

52. n There are two methods for naming cations with multiple charges n The Stock System and Classical System n The Stock system is the preferred method

53. Stock System n The stock system uses roman numerals in ( ). The ( ) indicate the numerical charge of the cation. Example: Fe 2+ Name: Iron(II) There is no space between the name and the parenthesis Example: Cu 1+ Name: Copper(1)

54. Classical System n The classical system uses the root word with different suffixes as the end of the word n OUS- is used to name the cation with the lower of the two ionic charges n IC- is used to name the cation with the higher of the two ionic charges

55. n Example: n Fe 2+ and Fe 3+ n Name: Ferrous n Name: Ferric n What is the problem with the classical system?

56. n The classical system does not tell you the charge of the ion. n The name only tells you which cation is either larger or smaller out of the pair

57. n Few transition metals have only one ionic charge n These three elements don’t have roman numerals next to there name n Exceptions: n Ag + n Cd 2+ n Zn 2+

58. Ionic compounds n If the cation is monoatomic- Name the metal (cation) just write the name. n If the cation is polyatomic- name it n If the anion is monoatomic- name it but change the ending to -ide n If the anion is poly atomic- just name it n practice

59. Naming Binary Ionic Compounds n Write the name of CuO n Need the charge of Cu n O is -2 n copper must be +2 n Copper (II) chloride n Name CoCl 3 n Cl is -1 and there are three of them = -3 n Co must be +3 Cobalt (III) chloride

60. Naming Binary Ionic Compounds n Write the name of Cu 2 S. n Since S is -2, the Cu 2 must be +2, so each one is +1. n copper (I) sulfide n Fe 2 O 3 n Each O is -2 3 x -2 = -6 n 3 Fe must = +6, so each is +2. n iron (III) oxide

61. Ternary Ionic Compounds n Will have polyatomic ions n At least three elements (3 capital letters) n Still just name the ions n NaNO 3 n CaSO 4 n CuSO 3

62. Ternary Ionic Compounds n LiCN n Fe(OH) 3 n (NH 4 ) 2 CO 3 n NiPO 4

63. Ionic Compounds n Have to know what ions they form n off table, polyatomic, or figure it out n CaS nK2SnK2SnK2SnK2S n AlPO 4 n K 2 SO 4 n FeS n CoI 3

64. Ionic Compounds n Fe 2 (C 2 O 4 ) n MgO n MnO n KMnO 4 n NH 4 NO 3 n Hg 2 Cl 2 n Cr 2 O 3

65. Ionic Compounds n KClO 4 n NaClO 3 n YBrO 2 n Cr(ClO) 6

66. Molecular Compounds Writing names and Formulas

67. Molecules & Molecular Compounds n Elements are the building materials of the substances that make up all living and nonliving things n Only about 100 elements but there are millions of different compounds made from their atoms n Thus, naming compounds is an essential skill in chemistry

68. n In nature, only Noble Gases tend to exist as isolated atoms. n They are monatomic; that is, they consist of single atoms n Many elements found in nature are in the form of molecules n Molecule- is the smallest electrically neutral unit of a substance that still has the properties of the substance n Molecules are made up of two or more atoms that act as a unit

69. n Atoms of different elements may combine chemically to form compounds n In many compounds, the atoms combine to form molecules. n Molecular Compounds- Compounds composed of molecules n Molecular Compounds tend to have relativity low melting and boiling points n Many of these compounds thus exist as gases or liquids at room temperature.

70. Molecular compounds n made of just nonmetals n smallest piece is a molecule n can’t be held together because of opposite charges. n can’t use charges to figure out how many of each atom

71. Naming Covalent Compounds n Two words, with prefixes n Prefixes tell you how many. n mono, di, tri, tetra, penta, hexa, septa, nona, deca n First element whole name with the appropriate prefix, except mono n Second element, -ide ending with appropriate prefix n Practice

72. © 2009, Prentice-Hall, Inc. Nomenclature of Binary Compounds n The less electronegative atom is usually listed first. n A prefix is used to denote the number of atoms of each element in the compound (mono- is not used on the first element listed, however).

73. © 2009, Prentice-Hall, Inc. Nomenclature of Binary Compounds n The ending on the more electronegative element is changed to -ide. –CO 2 : carbon dioxide –CCl 4 : carbon tetrachloride

74. © 2009, Prentice-Hall, Inc. Nomenclature of Binary Compounds n If the prefix ends with a or o and the name of the element begins with a vowel, the two successive vowels are often elided into one. N 2 O 5 : dinitrogen pentoxide

75. n CO 2 n CO n CCl 4 nN2O4nN2O4nN2O4nN2O4 n XeF 6 nN4O4nN4O4nN4O4nN4O4 n P 2 O 10 Naming Covalent Compounds

76. Name These nN2OnN2OnN2OnN2O n NO 2 n Cl 2 O 7 n CBr 4 n CO 2 n BaCl 2

77. Covalent compounds n The name tells you how to write the formula n duh n Sulfur dioxide n diflourine monoxide n nitrogen trichloride n diphosphorus pentoxide

78. Write formulas for these n diphosphorus pentoxide n tetraiodide nonoxide n sulfur hexaflouride n nitrogen trioxide n Carbon tetrahydride n phosphorus trifluoride n aluminum chloride

79. More Names and formulas

80. Acids n Substances that produce H + ions when dissolved in water n All acids begin with H n Two types of acids n Oxyacids n non oxyacids

81. Naming acids n If the formula has oxygen in it n write the name of the anion, but change –ate to -ic acid –ite to -ous acid n Watch out for sulfuric and sulfurous n H 2 CrO 4 n HMnO 4 n HNO 2

82. Naming acids n If the acid doesn’t have oxygen n add the prefix hydro- n change the suffix -ide to -ic acid n HCl nH2SnH2SnH2SnH2S n HCN

84. Formulas for acids n Backwards from names n If it has hydro- in the name it has no oxygen n anion ends in -ide n No hydro, anion ends in -ate or -ite n Write anion and add enough H to balance the charges.

85. Formulas for acids n hydrofluoric acid n dichromic acid n carbonic acid n hydrophosphoric acid n hypofluorous acid n perchloric acid n phosphorous acid

86. 3-86 Naming Acids Summary Figure 3.35

87. 3-87 Naming Acids n Since most acids have a hydrogen as their 1 st element in the molecular formula, the acids are named according to the anion, not the cation (H + ). n Binary acids are named as hydro- followed by the root of the element (2 nd element or anion) name with an –ic suffix and the word acid placed at the end of the name. n Acids containing polyatomic ions (as the anion) are named by taking the root of the polyatomic ion name, replacing –ate with –ic or replacing –ite with –ous and adding the word acid at the end.

88. Hydrates n Some salts trap water crystals when they form crystals n these are hydrates. n Both the name and the formula needs to indicate how many water molecules are trapped n In the name we add the word hydrate with a prefix that tells us how many water molecules

89. Hydrates n In the formula you put a dot and then write the number of molecules. Calcium chloride dihydrate = CaCl 2  2  Calcium chloride dihydrate = CaCl 2  2  Chromium (III) nitrate hexahydrate = Cr(NO 3 ) 3  6H 2 O Chromium (III) nitrate hexahydrate = Cr(NO 3 ) 3  6H 2 O

90. 3-90 Predicting Properties and Naming Compounds Summary n Before naming a compound, you must first classify it as either an ionic compound, molecular compound, or acid. –If it is an ionic compound, you must also decide if the cation is an ion that can vary in charge. n These classifications allow you to name the compound with the proper rules.

91. 3-91 Naming Compounds Summary Figure 3.36