1. Chapter 2 Atoms, Molecules, and Ions

2. History Greeks Greeks Democritus and Leucippus - atomos Democritus and Leucippus - atomos Aristotle- elements Aristotle- elements Alchemy Alchemy 1660 - Robert Boyle- experimental definition of element. 1660 - Robert Boyle- experimental definition of element. Lavoisier- Father of modern chemistry Lavoisier- Father of modern chemistry He wrote the book- used measurement He wrote the book- used measurement

3. Laws Conservation of Mass Conservation of Mass Law of Definite Proportion- compounds have a constant composition by mass. Law of Definite Proportion- compounds have a constant composition by mass. They react in specific ratios by mass. They react in specific ratios by mass. 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. 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.

4. What?! Water has 8 g of oxygen per g of hydrogen. Water has 8 g of oxygen per g of hydrogen. Hydrogen peroxide has 16 g of oxygen per g of hydrogen. Hydrogen peroxide has 16 g of oxygen per g of hydrogen. 16/8 = 2/1 16/8 = 2/1 Small whole number ratios Small whole number ratios

5. Dalton’s Atomic Theory 1. Elements are made up of atoms 1. Elements are made up of atoms 2. Atoms of each element are identical. Atoms of different elements are different. 2. Atoms of each element are identical. Atoms of different elements are different. 3. Compounds are formed when atoms combine. Each compound has a specific number and kinds of atom. 3. Compounds are formed when atoms combine. Each compound has a specific number and kinds of atom. 4. Chemical reactions are rearrangement of atoms. Atoms are not created or destroyed. 4. Chemical reactions are rearrangement of atoms. Atoms are not created or destroyed.

6. Gay-Lussac- under the same conditions of temperature and pressure, compounds always react in whole number ratios by volume. Gay-Lussac- under the same conditions of temperature and pressure, compounds always react in whole number ratios by volume. Avagadro- interpreted that to mean Avagadro- interpreted that to mean at the same temperature and pressure, equal volumes of gas contain the same number of particles at the same temperature and pressure, equal volumes of gas contain the same number of particles (called Avagadro’s hypothesis) (called Avagadro’s hypothesis) A Helpful Observation

7. Experiments to determine what an atom was J. J. Thomson- used Cathode ray tubes J. J. Thomson- used Cathode ray tubes

8. Thomson’s Experiment Voltage source +-

9. Thomson’s Experiment Voltage source +-

10. Thomson’s Experiment Voltage source +-

11. Passing an electric current makes a beam appear to move from the negative to the positive end Passing an electric current makes a beam appear to move from the negative to the positive end Thomson’s Experiment Voltage source +-

12. Passing an electric current makes a beam appear to move from the negative to the positive end Passing an electric current makes a beam appear to move from the negative to the positive end Thomson’s Experiment Voltage source +-

13. Passing an electric current makes a beam appear to move from the negative to the positive end Passing an electric current makes a beam appear to move from the negative to the positive end Thomson’s Experiment Voltage source +-

14. Passing an electric current makes a beam appear to move from the negative to the positive end Passing an electric current makes a beam appear to move from the negative to the positive end Thomson’s Experiment Voltage source +-

15. Thomson’s Experiment By adding an electric field By adding an electric field

16. Voltage source Thomson’s Experiment By adding an electric field By adding an electric field + -

17. Voltage source Thomson’s Experiment By adding an electric field By adding an electric field + -

18. Voltage source Thomson’s Experiment By adding an electric field By adding an electric field + -

19. Voltage source Thomson’s Experiment By adding an electric field By adding an electric field + -

20. Voltage source Thomson’s Experiment By adding an electric field By adding an electric field + -

21. Voltage source Thomson’s Experiment By adding an electric field he found that the moving pieces were negative By adding an electric field he found that the moving pieces were negative + -

22. Thomsom’s Model Found the electron Found the electron Couldn’t find positive (for a while) Couldn’t find positive (for a while) Said the atom was like plum pudding Said the atom was like plum pudding A bunch of positive stuff, with the electrons able to be removed A bunch of positive stuff, with the electrons able to be removed

23. Millikan’s Experiment Atomizer Microscope - + Oil

24. Millikan’s Experiment Oil Atomizer Microscope - + Oil droplets

25. Millikan’s Experiment X-rays X-rays give some drops a charge by knocking off electrons

26. Millikan’s Experiment +

27. They put an electric charge on the plates + + --

28. Millikan’s Experiment Some drops would hover + + --

29. Millikan’s Experiment + ++ +++++ -- -----

30. Measure the drop and find volume from 4/3πr 3 Find mass from M = D x V + + --

31. Millikan’s Experiment From the mass of the drop and the charge on the plates, he calculated the charge on an electron + + --

32. Radioactivity Discovered by accident Discovered by accident Bequerel Bequerel Three types Three types alpha- helium nucleus (+2 charge, large mass)alpha- helium nucleus (+2 charge, large mass) beta- high speed electronbeta- high speed electron gamma- high energy lightgamma- high energy light

33. Rutherford’s Experiment Used uranium to produce alpha particles Used uranium to produce alpha particles Aimed alpha particles at gold foil by drilling hole in lead block Aimed alpha particles at gold foil by drilling hole in lead block Since the mass is evenly distributed in gold atoms alpha particles should go straight through. Since the mass is evenly distributed in gold atoms alpha particles should go straight through. Used gold foil because it could be made atoms thin Used gold foil because it could be made atoms thin

34. Lead block Uranium Gold Foil Florescent Screen

35. What he expected

36. Because

37. Because, he thought the mass was evenly distributed in the atom

38. What he got

39. How he explained it + Atom is mostly empty Atom is mostly empty Small dense, positive piece at center Small dense, positive piece at center Alpha particles are deflected by it if they get close enough Alpha particles are deflected by it if they get close enough

40. +

41. Modern View The atom is mostly empty space The atom is mostly empty space Two regions Two regions Nucleus- protons and neutrons Nucleus- protons and neutrons Electron cloud- region where you have a chance of finding an electron Electron cloud- region where you have a chance of finding an electron

42. Sub-atomic Particles Z - atomic number = number of protons determines type of atom Z - atomic number = number of protons determines type of atom A - mass number = number of protons + neutrons A - mass number = number of protons + neutrons Number of protons = number of electrons if neutral Number of protons = number of electrons if neutral

43. Symbols X A Z Na 23 11

44. Chemical Bonds The forces that hold atoms together The forces that hold atoms together Covalent bonding - sharing electrons Covalent bonding - sharing electrons makes molecules makes molecules Chemical formula- the number and type of atoms in a molecule Chemical formula- the number and type of atoms in a molecule C 2 H 6 - 2 carbon atoms, 6 hydrogen atoms, C 2 H 6 - 2 carbon atoms, 6 hydrogen atoms, Structural formula shows the connections, but not necessarily the shape. Structural formula shows the connections, but not necessarily the shape.

45. H H HH H HCC Structural Formula Structural Formula

46. There are also other model that attempt to show three dimensional shape There are also other model that attempt to show three dimensional shape Ball and stick (see the models in room) Ball and stick (see the models in room) Space Filling Space Filling

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

48. Polyatomic Ions Groups of atoms that have a charge Groups of atoms that have a charge Yes, you have to memorize them. Yes, you have to memorize them. List on page 65 List on page 65

49. Periodic Table

50. Metals Conductors Conductors Lose electrons Lose electrons Malleable and ductile Malleable and ductile

51. Nonmetals Brittle Brittle Gain electrons Gain electrons Covalent bonds Covalent bonds

52. Semi-metals or Metalloids

53. Alkali Metals

54. Alkaline Earth Metals

55. Halogens

56. Transition metals

57. Noble Gases

58. Inner Transition Metals

59. +1+2-2-3

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

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

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

63. More Naming

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

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

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

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

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

69. CO 2 CO 2 CO CO CCl 4 CCl 4 N 2 O 4 N 2 O 4 XeF 6 XeF 6 N 4 O 4 N 4 O 4 P 2 O 10 P 2 O 10 Naming Covalent Compounds

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

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

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

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

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

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

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

77. More Names and formulas

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

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

80. Naming acids If the acid doesn’t have oxygen If the acid doesn’t have oxygen add the prefix hydro- add the prefix hydro- change the suffix -ide to -ic acid change the suffix -ide to -ic acid HCl HCl H 2 S H 2 S HCN HCN

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

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

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

84. Hydrates In the formula you put a dot and then write the number of molecules. 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