ISM_Chapter_02

# ISM_Chapter_02 - CHAPTER 2: ATOMS, MOLECULES, AND IONS...

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CHAPTER 2: ATOMS, MOLECULES, AND IONS CHAPTER 2 ATOMS, MOLECULES, AND IONS 2.8 First, convert 1 cm to picometers. 10 12 0.01 m 1 pm 1 cm 1 10 pm 1 cm 1 10 m - = 10 2 1 He atom (1 10 pm) 1 10 pm = = 8 ? He atoms 1 10 He atoms . 2.9 Note that you are given information to set up the unit factor relating meters and miles. 4 4 nucleus 1 m 1 mi 10 10 2.0 cm 100 cm 1609 m = = = atom 0.12 mi r r 2.14 For iron, the atomic number Z is 26. Therefore the mass number A is: A = 26 + 28 = 54 2.15 Strategy: The 239 in Pu-239 is the mass number. The mass number ( A ) is the total number of neutrons and protons present in the nucleus of an atom of an element. You can look up the atomic number (number of protons) on the periodic table. Solution: mass number = number of protons + number of neutrons number of neutrons = mass number - number of protons = 239 - 94 = 145 2.16 Isotope 3 2 He 4 2 He 24 12 Mg 25 12 Mg 48 22 Ti 79 35 Br 195 78 Pt No. Protons 2 2 12 12 22 35 78 No. Neutrons 1 2 12 13 26 44 117 2.17 Isotope 7 15 N 16 33 S 29 63 Cu 38 84 Sr 56 130 Ba 74 186 W 80 202 Hg No. Protons 7 16 29 38 56 74 80 No. Electrons 7 16 29 38 56 74 80 No. Neutrons 8 17 34 46 74 112 122 2.18 (a) 23 11 Na (b) 64 28 Ni (c) Sn 115 50 (d) Ca 42 20 2.19 The accepted way to denote the atomic number and mass number of an element X is X A Z where A = mass number and Z = atomic number. (a) 74 186 W (b) 80 201 Hg (c) Se 76 34 (d) Pu 239 94 2.20 (a) 10 (b) 26 (c) 81 (d) 196 26

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CHAPTER 2: ATOMS, MOLECULES, AND IONS 2.21 (a) 19 (b) 34 (c) 75 (d) 192 2.22 198 Au: 119 neutrons, 47 Ca: 27 neutrons, 60 Co: 33 neutrons, 18 F: 9 neutrons, 125 I: 72 neutrons, 131 I: 78 neutrons, 42 K: 23 neutrons, 43 K: 24 neutrons, 24 Na: 13 neutrons, 32 P: 17 neutrons, 85 Sr: 47 neutrons, 99 Tc: 56 neutrons. 2.28 Helium and Selenium are nonmetals whose name ends with ium . (Tellurium is a metalloid whose name ends in ium .) 2.29 (a) Metallic character increases as you progress down a group of the periodic table. For example, moving down Group 4A, the nonmetal carbon is at the top and the metal lead is at the bottom of the group. (b) Metallic character decreases from the left side of the table (where the metals are located) to the right side of the table (where the nonmetals are located). 2.30 The following data were measured at 20 ° C. (a) Li (0.53 g/cm 3 ) K (0.86 g/cm 3 ) H 2 O (0.98 g/cm 3 ) (b) Au (19.3 g/cm 3 ) Pt (21.4 g/cm 3 ) Hg (13.6 g/cm 3 ) (c) Os (22.6 g/cm 3 ) (d) Te (6.24 g/cm 3 ) 2.31 Na and K are both Group 1A elements; they should have similar chemical properties. N and P are both Group 5A elements; they should have similar chemical properties. F and Cl are Group 7A elements; they should have similar chemical properties. 2.32
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## This note was uploaded on 09/16/2009 for the course CHEM 1001 taught by Professor Yi during the Fall '09 term at Marquette.

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ISM_Chapter_02 - CHAPTER 2: ATOMS, MOLECULES, AND IONS...

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