Ch2 z53 particles

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  • 1.Chapter 2 Atoms, Molecules, and Ions pp

2. History Greeks Democritus and Leucippus -atomos Aristotle- elements. Alchemy 1660 - Robert Boyle- experimental definition of element. Lavoisier- Father of modern chemistry. He wrote the book. 3. Laws Conservation of Mass Law of Definite Proportion - compounds have a constant composition. 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. 4. What?! Water has 8 g of oxygen per g of hydrogen. Hydrogen peroxide has 16 g of oxygen per g of hydrogen. 16/8 = 2/1 Small whole number ratios. 5. Proof Mercury has two oxides. One is 96.2 % mercury by mass, the other is 92.6 % mercury by mass. Show that these compounds follow the law of multiple proportion. Speculate on the formula of the two oxides. 6. Daltons Atomic Theory Elements are made up of atoms Atoms ofeachelement are identical. Atoms ofdifferentelements are different. Compoundsare formed when atoms combine.Each compound has a specific number and kinds of atom. Chemical reactions are rearrangement of atoms. Atoms are not created or destroyed. 7. Gay-Lussac- under the same conditions of temperature and pressure, compounds always react in whole number ratios by volume. Avagadro - interpreted that to mean . . .at the same temperature and pressure, equal volumes of gas contain the same number of particles. (calledAvagadros Hypothesis ) A Helpful Observation 8. Figure 2.4 Representation of some of Gay-Lussacs Experimental Results on Combining Gas Volumes 9. Figure 2.5Representation of Combining Gases at the Molecular Level 10. Early Experiments to determine what an atom was J. J. Thomson- used Cathode ray tubes 11. Thomsons Experiment + - Voltage source 12. Thomsons Experiment + - Voltage source 13. Passing an electric current makes a beam appear to move from the negative to the positive end. Thomsons Experiment + - Voltage source 14. Thomsons Experiment By adding an electric fieldVoltage source 15. Thomsons Experiment By adding an electric field, he found that the moving pieces were negative+ - Voltage source 16. Thomsoms Model Found the electron. Couldnt find positive (for a while).Said the atom was like plum pudding. A bunch of positive stuff, with the electrons able to be removed. 17. Millikans Experiment Oil Atomizer Oil droplets Telescope - + 18. Millikans Experiment X-rays X-rays give some electrons a charge. 19. Millikans Experiment Some drops would hover From the mass of the drop and the charge onthe plates, he calculated the mass of an electron 20. Figure 2.10 Diagram of the Millikan Apparatus 21. Radioactivity Discovered by accident Bequerel Three typesAlpha- helium nucleus (+2 charge, large mass) Beta - high speed electron Gamma - high energy light 22. Rutherfords Experiment Used uranium to produce alpha particles. Aimed alpha particles at gold foil by drilling hole in lead block. Since the mass is evenly distributed ingold atoms alpha particles should go straight through. Used gold foil because it could be made atoms thin. 23. Lead block Uranium Gold Foil FlorescentScreen 24. What he expected 25. Because 26. Because, he thought the mass was evenly distributed in the atom. 27. What he got 28. Atom is mostly empty Small dense,positive piece at center. Alpha particles are deflected byit if they get closeenough. How he explained it + 29. + 30. Figure 2.12 Rutherfords Experiment on particle Bombardment of Metal Foil 31. Figure 2.13Expected and Actual Results of Rutherfords Experiment 32. Modern View The atom is mostly empty space. Two regions Nucleus - protons and neutrons. Electron cloud - region where youmightfind an electron. 33. Sub-atomic Particles Z - atomic number = number of protons Z determines type of atom. A - mass number = number of protons + neutrons. Number of protons = number of electronsif neutral. 34. The Mass and Change of the Electron, Proton, and Neutron 35. Symbols X A Z Na 23 11 36. Chemical Bonds The forces that hold atoms together. Covalent bonding - sharing electrons. Makes molecules. Chemical formula - the number and type of atoms in a molecule.C 2 H 6- 2 carbon atoms, 6 hydrogen atoms,Structural formula shows the connections, but not necessarily the shape. 37. There are also other models that attempt to show three dimensional shape. Ball and stick or space-filling. H H H H H H C C 38. Ions Atoms or groups of atoms with a charge. Cations - positive ions - get bylosingelectrons(s). Anions- negative ions - get bygainingelectron(s). Ionic bonding - held together by the opposite charges. Ionicsolidsare called salts. 39. Polyatomic Ions Groups of atoms that have a charge. Yes, you have to memorize them. See list on page 66 40. Periodic Table 41. Metals Conductors Lose electrons Malleable and ductile 42. Nonmetals Brittle Gain electrons Covalent bonds 43. Semi-metals or Metalloids 44. Alkali Metals 45. Alkaline Earth Metals 46. Halogens 47. Transition metals 48. Noble Gases 49. Inner Transition Metals 50. +1 +2 -1 -2 -3 51. Naming compounds Two types Ionic- metal with non metal or with polyatomic ions. Covalent - we will just learn the rules for non-metals combined with non-metal. 52. Ionic compounds If thecationis monoatomic - Name the metal (cation) just write the name. Include a Roman numeral to indicate the oxidation state if the cation (metal) has more than one. If the cation is polyatomic - name it. If the anion is monoatomic - name it but change the ending toide. If the anion is poly atomic - just name it Practice. 53. Figure 2.22Common Cations and Anions 54. Covalent compounds Two words, with prefixes. Prefixes tell you how many. mono, di, tri, tetra, penta, hexa, septa, nona, deca First element- use whole name with the appropriate prefix, except mono. Second element,-ideending with appropriate prefix. Practice 55. More Naming 56. Ionic compounds If the cation is monoatomic- Name the metal (cation) just write the name. If the cation is polyatomic- name it If the anion is monoatomic- name it but change the ending to-ide If the anion is poly atomic- just name it Practice problems on following slides 57. Ionic Compounds Have to know what ions they form Get from periodic table, polyatomic, or figure out CaS K 2 S AlPO 4 K 2 SO 4 FeS CoI 3 58. Figure 2.23 Flowchart for Naming BinaryCompounds 59. Figure 2.24 Overall Strategy for Naming Chemical Compounds 60. Ionic Compounds Fe 2 (C 2 O 4 ) MgO MnO KMnO 4 NH 4 NO 3 Hg 2 Cl 2 Cr 2 O 3 61. Ionic Compounds KClO 4 NaClO 3 YBrO 2 Cr(ClO) 6 62. Naming Covalent Compounds Two words, with prefixes Prefixes tell you how many. mono, di, tri, tetra, penta, hexa, septa, nona, deca First element whole name with the appropriate prefix, except mono Second element,-ideending with appropriate prefix Practice 63. CO 2 COCCl 4 N 2 O 4 XeF 6 N 4 O 4 P 2 O 10 Naming Covalent Compounds 64. Writing Formulas Two sets of rules, ionic and covalent To decide which to use, decide what the first word is. If is a metal or polyatomic use ionic. If it is a non-metal use covalent. 65. Ionic Formulas Charges must add up to zero. Get charges from periodic table, name of metal ion, or memorized from the list. Use parentheses to indicate multiple polyatomics. 66. Ionic Formulas Sodium nitride Sodium - Na is always +1 nitride - ide tells you it comes from the periodic table nitride is N -3 67. Ionic Formulas Sodium nitride Sodium - Na is always +1 Nitride - ide tells you it comes from the table nitride is N -3 Doesnt add up to zero (if 1:1 ratio). Na +1 N -3 68. Ionic Formulas Sodium nitride sodium- Na is always +1 nitride - ide tells you it comes from the table nitride is N -3 Doesnt add up to zero So, need 3 Na (Cross the charges) Na +1 N -3 Na 3 N 69. Ionic Compounds Sodium sulfite calcium iodide Lead (II) oxideLead (IV) oxide Mercury (I) sulfide Barium chromate Aluminum hydrogen sulfate Cerium (IV) nitrite 70. Covalent compounds The name tells you how to write the formula duh Sulfur dioxide difluorine monoxide nitrogen trichloride diphosphorus pentoxide 71. Chemical Namingpp : P = cation Q = anion 72. More Names and formulas 73. Acids Substances that produce H +ions when dissolved in water. All acids begin with H. Two types ofinorganicacids:Oxyacids Non-oxyacids Organicacids have -COOH group 74. Naming acids If the formula has oxygen in it write the name of the anion, but changeate to -ic acid ite to -ous acid Hint:m -ic- e or more than a m -ous- e Watch out for sulf ur ic and sulf ur ous H 2 CrO 4 HMnO 4 HNO 2 75. Naming acids If the acid doesnt have oxygen add the prefix hydro- change the suffix -ideto -ic acid HCl H 2 S HCN 76. Formulas for acids Working backwards from names. If it has hydro- in the name it has no oxygen Anion ends in -ide No hydro, anion ends in -ate or -ite (and it is an oxyacid) Write anion and add enough H to balance the charges. 77. Figure 2.25Flowchart for Naming Acidspp 78. Formulas for acids hydrofluoric acid dichromic acid carbonic acid hydrophosphoric acid hypofluorous acid perchloric acid phosphorous acid 79. Hydrates Some salts trap water crystals when they form crystals. These are hydrates. Both the name and the formula need 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. 80. Hydrates pp In the formula you put a dot and then write the number of molecules. Calcium chloride dihydrate = CaCl 2 2 Chromium (III) nitrate hexahydrate = Cr(NO 3 ) 3 6H 2 O