Chapter2 - Chapter 2: Matter Chem 6A Michael J. Sailor, UC...

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Unformatted text preview: Chapter 2: Matter Chem 6A Michael J. Sailor, UC San Diego 1 Properties of sub-atomic particles Name Symbol Charge* Mass, g Electron e ­  ­1 9.1 x 10 ­28 Proton p +1 1.673 x 10 ­24 Neutron n 0 1.675 x 10 ­24 *units are fundamental unit of charge, = 1.602 x 10-19 coulombs Chem 6A Michael J. Sailor, UC San Diego 2 The Periodic Table of the Elements 1 18 1 H 2 2 1.0079 3 13 14 15 6.941 9.01218 11 12 10.811 13 12.011 14.0067 15.9994 18.9984 20.1797 14 15 16 17 18 Al Si Na Mg 22.9898 19 K 39.0983 37 Rb 85.4578 55 Cs B 3 24.305 20 Ca 4 21 22 Sc Y Ra 24 V 8 25 Cr Zr La Hf Ta Co 55.847 58.9332 44 45 Tc W 10 27 Fe Ru 95.94 98.9063 74 75 178.49 180.948 104 105 9 26 Mn Nb Mo 91.224 92.9064 72 73 132.905 137.327 138.906 87 88 89 Fr 7 47.88 50.9415 51.9961 54.9381 40 41 42 43 87.62 88.9059 56 57 Ba 6 23 Ti 40.078 44.9559 38 39 Sr 5 Rh 101.07 102.906 76 77 Re Os 183.85 186.207 106 107 Ir 190.2 108 192.22 109 28 Ni 58.69 46 Pd 11 29 Cu 63.546 47 Ag 12 C N P 26.9815 28.0855 30.9738 30 31 32 33 Zn 65.39 48 Cd Ga 69.723 49 Ge As 72.61 74.9216 50 51 In Sn Sb 106.42 107.868 112.411 78 79 80 114.82 81 118.71 82 121.75 83 Pt Tl Pb Au Hg 195.08 196.967 200.59 204.383 207.2 Bi 8 O S 9 4.0026 10 5 Be 7 He 17 4 Li 6 16 F Cl Ne Ar 32.066 35.4527 34 35 39.948 36 Se Kr 78.96 52 Te Br 79.904 53 I Xe 127.6 126.905 84 85 Po 83.8 54 At 131.29 86 Rn 208.98 208.982 209.987 222.018 Ac Unq Unp Unh Uns Uno Une 223.02 226.025 227.028 - 58 59 60 61 62 63 64 65 Actinides Ce Pr Nd Pm Sm Eu Gd Tb 140.12 90 Lanthanides 140.91 91 144.24 92 157.25 96 158.92 97 Th 232.038 Pa 231.04 U 238.03 146.92 93 150.35 94 151.96 95 66 67 Dy Ho 162.5 98 71 164.93 99 167.26 100 168.93 101 174.97 103 Fm Md No Pu Am Cm Bk Cf Es 239.05 251.08 254.09 249.08 70 Lu 237.05 247.07 69 Tm Yb Np 241.06 68 Er 257.1 258.1 173.04 102 255 Lr 262.1 Chem 6A Michael J. Sailor, UC San Diego 3 3 key experiments leading to the modern view of the atom Person Experiment What it determined J.J. Thomson 1897 Effect of a charged plates on a cathode ray tube mass/charge ratio of an electron, me/ze Robert Millikan 1909 Oil-drop experiment: suspending charge on the electron, ze a charged drop of oil between two charged plates Scattering of alpha-rays from Atom consists of a very small, metal foils very dense nucleus Ernest Rutherford 1910 Chem 6A Michael J. Sailor, UC San Diego 4 Cathode Ray (or Crookes) Tube measures the charge/mass ratio of the electron Electrons Effect of magnetic and electric fields on the deflection of the beam can determine the mass to charge ratio, me/ze Chem 6A Michael J. Sailor, UC San Diego 5 The CRT television display is a descendant of the Crookes tube Chem 6A Michael J. Sailor, UC San Diego 6 Determination of the mass of the electron Chem 6A Michael J. Sailor, UC San Diego 7 Problem: charge on the electron 5 10 4 10 2.40 x 10-9 3 10 -9 2 10 -9 1 10 charge, esu 1.92 x 10-9 -9 -9 charge, esu Charge on oil drop (esu) 9.60 x 10-10 -9 2.88 x 10-9 4.80 x 10-9 0 1 2 3 4 5 6 7 8 9 10 measurement Determine the fundamental charge on the electron, in esu Chem 6A Michael J. Sailor, UC San Diego 8 Solution: charge on the electron 5 10 -9 4 10 -9 3 10 -9 2 10 -9 1 10 -9 charge, esu charge, esu (1) Sort by charge: 0 9 1 6 2 3 4 10 8 5 7 measurement Chem 6A Michael J. Sailor, UC San Diego 9 Solution: charge on the electron charge, esu/9.6 x10 (1) Sort by charge: (2) Divide by smallest charge: -10 6 5 Divide by LCD 4 3 2 1 0 9 1 6 2 3 4 10 8 5 7 measurement Chem 6A Michael J. Sailor, UC San Diego 10 Solution: charge on the electron charge, esu/9.6 x10 (1) Sort by charge: (2) Divide by smallest charge: (3) Multiply by 2: -10 12 11 10 9 8 7 6 5 4 3 2 1 0 multiply by 2 9 1 6 2 3 4 10 8 5 7 measurement Chem 6A Michael J. Sailor, UC San Diego 11 Solution: charge on the electron Esu Divide by 9.6 x 10-10 Multiply by 2 9.60x10-10 1 2 1.92x10-9 2 4 2.40x10-9 2.5 5 2.88x10-9 3 6 4.80x10-9 5 10 So the fundamental charge on the electron is: (9.6 x 10-10)/2 = 4.8 x 10-10 esu Chem 6A Michael J. Sailor, UC San Diego 12 Discovery of the nucleus Chem 6A Michael J. Sailor, UC San Diego 13 3 key experiments leading to the modern view of the atom Person Experiment What it determined J.J. Thomson 1897 Effect of a charged plates on a cathode ray tube mass/charge ratio of an electron, me/ze Robert Millikan 1909 Oil-drop experiment: suspending charge on the electron, ze a charged drop of oil between two charged plates Scattering of alpha-rays from Atom consists of a very small, metal foils very dense nucleus Ernest Rutherford 1910 Chem 6A Michael J. Sailor, UC San Diego 14 A mass spectrometer measures masses of ions Chem 6A Michael J. Sailor, UC San Diego 15 Definition of atom masses is based on 12C • A carbon-12 atom is defined as our mass standard • it weighs exactly 12 atomic mass units (amu). • 1 amu = 1.66054 x 10-24g …so why does the periodic table list C as 12.011? Chem 6A Michael J. Sailor, UC San Diego 16 Mass ratios, isotopes, and %abundance De cre as in gm as s 12C, 13C 12C 13C Less13C: smaller spot More 12C: bigger spot Chem 6A Michael J. Sailor, UC San Diego 17 Isotopes: mass ratios and percent abundance Element Mass Abundance 12C (position on detector) (intensity on detector) 12.00 98.89 13C 13.003355 1.11 Mass ratio: 1.0836129 Mass ratio: 13 C 13.003355 = = 1.0836129 12 12 C Chem 6A Michael J. Sailor, UC San Diego 18 Problem: percent abundance of isotopes A student uses a mass spectrometer to determine the masses and percent abundances of all the naturally occurring isotopes of chlorine, the values of which are presented below. Calculate the average mass of chlorine, in amu. Isotope % abundant Atomic Mass, amu 35 Cl 75.77 % 34.97 37 Cl 24.23 % 36.97 Chem 6A Michael J. Sailor, UC San Diego 19 Solution: percent abundance of the isotopes This is just a weighted average: Mass = (0.7577 x 34.97) + (0.2423 x 36.97) = 35.45 amu The average of all naturally occurring isotopes is called the atomic mass (or atomic weight) of an element Chem 6A Michael J. Sailor, UC San Diego 20 The Periodic Table of the Elements 1 18 1 H 2 2 1.0079 3 13 14 15 6.941 9.01218 11 12 10.811 13 12.011 14.0067 15.9994 18.9984 20.1797 14 15 16 17 18 Al Si Na Mg 22.9898 19 K Rb Cs 4 21 Ra 7 24 V 8 25 Cr Y Zr Nb Mo 91.224 92.9064 72 73 La Hf Ta Co 55.847 58.9332 44 45 Tc W 10 27 Fe Ru 95.94 98.9063 74 75 178.49 180.948 104 105 9 26 Mn 47.88 50.9415 51.9961 54.9381 40 41 42 43 132.905 137.327 138.906 87 88 89 Fr 6 23 Ti 87.62 88.9059 56 57 Ba 5 22 Sc 40.078 44.9559 38 39 Sr 85.4578 55 3 24.305 20 Ca 39.0983 37 B Rh 101.07 102.906 76 77 Re Os 183.85 186.207 106 107 Ir 190.2 108 192.22 109 28 Ni 58.69 46 Pd 11 29 Cu 63.546 47 Ag 12 C N P 26.9815 28.0855 30.9738 30 31 32 33 Zn 65.39 48 Cd Ga 69.723 49 Ge As 72.61 74.9216 50 51 In Sn Sb 106.42 107.868 112.411 78 79 80 114.82 81 118.71 82 121.75 83 Pt Tl Pb Au Hg 195.08 196.967 200.59 204.383 207.2 Bi 8 O 9 4.0026 10 5 Be 7 He 17 4 Li 6 16 F S Ne Cl Ar 32.066 35.4527 34 35 39.948 36 Se Kr Br 78.96 52 Te 79.904 53 I Xe 127.6 126.905 84 85 Po 83.8 54 At 131.29 86 Rn 208.98 208.982 209.987 222.018 Ac Unq Unp Unh Uns Uno Une 223.02 226.025 227.028 - 58 59 60 61 62 63 64 65 Ce Pr Nd Pm Sm Eu Gd Tb 140.12 90 Lanthanides 140.91 91 144.24 92 157.25 96 158.92 97 Th Actinides 232.038 Pa 231.04 U 238.03 146.92 93 150.35 94 151.96 95 66 67 Dy Ho 162.5 98 71 164.93 99 167.26 100 168.93 101 174.97 103 Fm Md No Pu Am Cm Bk Cf Es 239.05 251.08 254.09 249.08 70 Lu 237.05 247.07 69 Tm Yb Np 241.06 68 Er 257.1 173.04 102 258.1 Lr 255 262.1 Chem 6A Michael J. Sailor, UC San Diego 21 Bonding in Compounds covalent ionic Na+ H O water molecule H Cl Cl Cl- chlorine molecule Covalent bond = neutral atoms held together by sharing a pair of electrons Ionic bond = charged atoms (ions) held together by electrostatic forces Coulomb’s law: z1z2q 2 E= 4 πεo r1− 2 Chem 6A Michael J. Sailor, UC San Diego charge distance 22 The rock salt lattice Ionic solids are held together by ionic bonds Chem 6A Michael J. Sailor, UC San Diego 23 Energy of an ionic bond Ionic bond = charged atoms (ions) held together by electrostatic forces Coulomb’s law: 0.281 nm Cl- Na+ z1z2q 2 E= 4 πεo r1− 2 charge distance Energy of attraction between 1 Na+ and 1 Cl- is (+1)( −1)(1.602 × 10 −19 ) 2 z1z2q 2 € = E= 4 πε o r1− 2 (4)(3.14)(8.85 × 10 −12 )(2.81 × 10 −10 ) = 8.2 × 10 −19 J Chem 6A Michael J. Sailor, UC San Diego 24 Lattice enthalpies and ionic radius Lattice enthalpy = energy that holds the crystal together Lattice Enthalpy vs 1/(Ionic radii) Lattice enthalpy, kJ/mol 950 Ion FCl- 800 19.6 I- 850 18.1 Br- NaF 900 Radius (pm) 13.3 22.0 NaCl 750 NaBr 700 NaI 650 3 3.2 3.4 3.6 3.8 4 1/(Na-X) distance, Å 4.2 4.4 -1 The closer the ions, the stronger the lattice Chem 6A Michael J. Sailor, UC San Diego Silberberg, pg. 53: Common Monatomic Ions Chem 6A Michael J. Sailor, UC San Diego 25 Covalent bonds covalent H O water molecule H Cl Cl chlorine molecule Covalent bond = neutral atoms held together by sharing a pair of electrons •An assembly of atoms held together by covalent bonds is a molecule •If it has a net charge, it is called a molecular ion Chem 6A Michael J. Sailor, UC San Diego 27 Problem: Naming polyatomic ions (Table 2.5) Write the names of the following ions: 1. CH3CO2acetate 2. Cr2O72dichromate 3. ClO3chlorate 4. MnO4permanganate Memorize all the ions, names, formulas and charges in Table 2.3, 2.4, and 2.5 Chem 6A Michael J. Sailor, UC San Diego 28 Problem: What is the MOLAR MASS of Aspirin (acetylsalicylic acid): O OH H O H H CH3 O H (C9H8O4) Chem 6A Michael J. Sailor, UC San Diego 29 Solution: MOLAR MASS of Aspirin (acetylsalicylic acid): O OH H O H H CH3 O H (C9H8O4) = 9(12.011) + 8(1.0079) + 4(15.9994) = 180.16 g/mol Chem 6A Michael J. Sailor, UC San Diego 30 Problem: What is the percent by mass of carbon in Aspirin? O OH H O H H CH3 O H (C9H8O4) Chem 6A Michael J. Sailor, UC San Diego 31 Solution: elemental composition of aspirin Atom Number Molecular weight (g/mol) Mass % by mass C 9 12.011 108.099 60.00 H 8 1.0079 8.0632 4.48 O 4 15.9994 63.9976 35.52 TOTAL: Chem 6A Michael J. Sailor, UC San Diego 100.00 32 ...
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