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Happy Birthday Gertrude B. Elion (1918) Read for Wednesday: HOMEWORK – DUE Wednesday 1/25/17 BW 3a (Bookwork): CH 3 #'s 3, 4, 11-24 all, 26, 27 WS 3 (Worksheet): (from course website) HOMEWORK – DUE Wednesday 2/1/17 BW 2 (Bookwork): CH 2 #'s 1-7 all, 21, 23, 36, 47-50 all, 57, 59-66 all, 81, 82, 113, 114, 116, 127, 132 WS 2 (Worksheet): (from course website) HOMEWORK – DUE Monday 1/30/17 Chapter 3: Sections 3-4 BW 3b (Bookwork): CH 3 #'s 41, 45, 48, 56-61 all, 68, 70, 72, 73, 78, 79, 85, 88, 95, 96, 104, 119, 124 WS 4 (Worksheet): (from course website) Lab Wednesday/Thursday EXP 2 Prelab includes making flashcards!!!! Announcements Course Website Chem 311 – Strategies for Problem Solving in Chemistry Fridays from 12:00 – 2:25 PM in room 401 Before There Were Atoms… Three laws that lead to the atomic view of the atom: 1) Law of Conservation of Mass Total mass must be same before and after a reaction 2) Law of Definite Proportions No matter the source, a compound is always made of the same elements in the same mass ratio 3) Law of Multiple Proportions If two elements combine to form more than one type of compound with each other, the masses of one element that combined with a fixed mass of the other element are in ratios of small whole numbers Before There Were Atoms… Three laws that lead to the atomic view of the atom: 1) Law of Conservation of Mass Total mass must be same before and after a reaction I am BBQing and start with 20 pounds of charcoal. When I am done, there is only 4 pounds of ash left. How can we explain the apparent failure of the Law of Mass Conservation? 48.0 g of carbon react with 128 g of oxygen, how much CO2 should be formed? 176 g CO2(g) 48.0 g of carbon react with 148 g of oxygen. After the reaction is complete, there is still only 176 g of CO2 formed. Has the Law of Conservation of Mass failed? 20.0 g O2(g) left over Before There Were Atoms… Three laws that lead to the atomic view of the atom: 1) Law of Conservation of Mass Total mass must be same before and after a reaction 14.71 g of CrCl3 is added to 23.41 g of Pb(NO3)2. If all of the Pb(NO3)2 is used up and 11.22 g of Cr(NO3)3 and 19.66 g of PbCl2 are produced, what mass of CrCl3 remains? CrCl3(aq) + Pb(NO3)2(aq) Cr(NO3)3(aq) + PbCl2(s) total mass start 14.71 g 23.41 g 0g 0g 38.12 g end ?g 0g 11.22 g 19.66 g ? + 30.88 g 7.24 g Before There Were Atoms… Three laws that lead to the atomic view of the atom: 2) Law of Definite Proportions No matter the source, a compound is always made of the same elements in the same mass ratio 48.0 g of carbon react with 128 g of oxygen, forming 176 g CO2, how much CO2 should be formed from 72.0 g of carbon? 176 g CO 2 X g CO 2 = 48.0 g C 72.0 g C 72.0 g C X = 264 g CO2(g) 176 g CO 2 =X g CO 2 48.0 g C Before There Were Atoms… Three laws that lead to the atomic view of the atom: 2) Law of Definite Proportions No matter the source, a compound is always made of the same elements in the same mass ratio 48.0 g of carbon react with 128 g of oxygen, forming 176 g CO2, how much O2 should be react with 72.0 g of carbon? 128 g O 2 X g O 2 = 48.0 g C 72.0 g C 72.0 g C X = 192 g O2(g) 128 g O 2 =X g O 2 48.0 g C Before There Were Atoms… Three laws that lead to the atomic view of the atom: 2) Law of Definite Proportions No matter the source, a compound is always made of the same elements in the same mass ratio A 219.6 kg sample of NaCl from The Great Salt Lake contains 86.4 kg of sodium, what mass of chloride would be present in a 76.8 kg sample of NaCl from the Dead Sea? 219.6 kg NaCl – 86.4 kg Na = 133.2 kg Cl 133.2 kg Cl X g Cl = 219.6 kg NaCl 76.8 kg NaCl 76.8 kg NaCl X = 46.8 kg Cl 133.2 kg Cl =X g Cl 219.6 kg NaCl The Atom REALLY early atomic theory… Democritus ~350 BC Atomos - Greek meaning indivisible Modern Definition: Smallest piece that matter can be broken up into and still maintain the properties of an element My Atom Broke Subatomic Particles Nucleus Protons Carry – p+ a single positive charge Number of p+ = ATOMIC NUMBER 1.673x10–24 g VIIIA 18 IA 1 1 H 1.01 IIIA 13 IIA 2 IVA 14 VA 15 VIA 16 VIIA 17 2 He 4.00 3 4 5 6 7 8 9 10 Li Be B C N O F Ne 6.94 9.01 10.81 12.01 14.01 16.00 19.00 20.18 11 12 13 14 15 16 17 18 Na Mg 22.99 24.31 19 20 IIIB 3 IVB 4 VB 5 VIB 6 VIIB 7 VIII 8 VIII 9 VIII 10 IB 11 IIB 12 21 22 23 24 25 26 27 28 29 30 Al Si P S Cl Ar 26.98 28.09 30.97 32.07 35.45 39.95 31 32 33 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 39.10 40.08 44.96 47.88 50.94 52.00 54.94 55.85 58.93 58.69 63.55 65.39 69.72 72.61 74.92 78.96 79.90 83.80 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 85.47 87.62 88.91 91.22 92.91 95.94 (99) 101.07 102.91 106.42 107.87 112.41 114.82 118.71 121.75 127.60 126.90 131.29 55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 132.91 137.33 138.91 178.49 180.95 183.85 186.21 190.2 192.22 195.08 196.97 200.59 204.38 207.2 208.98 (209) (210) (222) 87 88 89 104 105 106 107 108 109 110 111 112 116 114 Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg -- -- -- (223) (226) (227) (261) (262) (263) (262) (265) (266) (271) (272) (277) (285) (289) 58 59 60 61 62 63 64 65 66 67 68 69 70 71 Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 140.12 140.91 144.24 (147) 150.36 151.97 157.25 158.93 162.50 164.93 167.26 168.93 173.04 174.97 90 91 92 93 94 95 96 97 98 99 100 101 102 103 Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr (232) (231) (238) (237) (244) (243) (247) (247) (251) (252) (257) (258) (259) (260) My Atom Broke Subatomic Particles Nucleus Neutrons – no No charge # can vary from atom to atom 1.675x10–24 g (roughly the same mass as p+) My Atom Broke Subatomic Particles Outside the nucleus Electrons – e– Carry a single negative charge ~1830 e – = mass of p+ or no 9.11x10 –28 g Responsible for most of the chemistry that ever happens because of their involvement in bonding Types of Bonding : Ionic Compounds Ionic bonding involves the complete TRANSFER of electrons from one atom to another. Usually observed when a metal bonds to a nonmetal. - - - + + + + + + + + + + + - - - - - + + + + + + + + + - - - Types of Bonding : Ionic Compounds Ionic bonding involves the complete TRANSFER of electrons from one atom to another. Usually observed when a metal bonds to a nonmetal. Metals have low ionization energy, making it relatively easy to remove electrons from them Nonmetals have high electron affinities, making it advantageous to add electrons to these atoms The oppositely charged ions are then attracted to each other, resulting in an ionic bond Types of Bonding: Ionic Compounds Ionic compounds tend to be hard, rigid, and brittle, with high melting points. Types of Bonding: Ionic Compounds Ionic compounds tend to be hard, rigid, and brittle, with high melting points. Ionic compounds do not conduct electricity in the solid state. In the solid state, the ions are fixed in place in the lattice and do not move. Types of Bonding: Ionic Compounds Ionic compounds tend to be hard, rigid, and brittle, with high melting points. Ionic compounds do not conduct electricity in the solid state. In the solid state, the ions are fixed in place in the lattice and do not move. Ionic compounds conduct electricity when melted or dissolved. In the liquid state or in solution, the ions are free to move and carry a current. Types of Bonding: Covalent Compounds Covalent bonding involves the SHARING of electrons Usually observed when a nonmetal bonds to a nonmetal. + + - - - - - 6p+ + - + Types of Bonding: Covalent Compounds Covalent bonding involves the SHARING of electrons Usually observed when a nonmetal bonds to a nonmetal. Nonmetal atoms have relatively high ionization energies, so it is difficult to remove electrons from them When nonmetals bond together, it is better in terms of potential energy for the atoms to share valence electrons Potential energy lowest when the electron is between the nuclei, holding the atoms together by attracting nuclei of both atoms Atoms vs. Ions Atoms are NEUTRAL!!!!! This means that they have zero charge #p+ = #e– Charge!!! 1 p+ 1 e– – 0 47 p+ 47 e– – 0 When #p+ = #e-, the atom has no charge and is neutral Atoms vs. Ions Atoms can gain or lose e- to form IONS ANY charged particle is called an ion Losing e- gives POSITIVELY charge Charge!!! 11 p+ =11 p+ 10 e- = 10 e– 11 When an atom LOSES electrons – +1 Before Na After Na+ + e- Atoms vs. Ions Atoms can gain or lose e- to form IONS ANY charged particle is called an ion Losing e- gives POSITIVELY charge Called cations Usually formed from metals Gaining e- gives a NEGATIVELY charged ion Charge!!! 16 p+ =16 p+ 16 e- = 18 e– 18 When an atom GAINS electrons – –2 Before S S + 2e- After S2- + 2e S2- WRONG!! Atoms vs. Ions Atoms can gain or lose e- to form IONS ANY charged particle is called an ion Losing e- gives POSITIVELY charge Called cations Usually formed from metals Gaining e- gives a NEGATIVELY charged ion Called anions Usually formed from non-metals My Atom Broke Subatomic Particles Nucleus Neutrons No – no charge # can vary from atom to atom + + 16p 16no 16p o 17n 16p+ o 18n 16p+ 20no + + 16p 16no 16p o 17n 16p+ o 18n 16p+ 20no Mass of no about equal to mass of p+ 16p+ 16no 16p+ 17no 16p+ 18no 16p+ 20no Do each of these atoms have the same mass? Isotopes: Atoms having the same atomic number, but different atomic masses + Atomic symbols 16p 16no Mass number = # p+ + # no 16p+ 17no A E S 16 Z 16p+ 18no Atomic number 16p+ 20no Symbol of element 16p+ 16no 32 S 16 16p+ 17no 33 S 16 16p+ 18no 34 S 16 16p+ 20no 36 S 16 A E Z 32 S 16 Shorthand: Sulfur-33 S-36 36S