#Chem 161-2007 Homework 10th week

#Chem 161-2007 Homework 10th week - Chem 161-2007 10th Week...

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Chem 161-2007 10 th Chapter 8 problems: 41,43,45,49,51,55,57,61,63,65,69,71,78,82,87 Electron configurations and the Periodic Table 41. Give the period number and group number for the element whose atoms have the electron configuration (a) 1s 2 2s 2 2p 6 The period number is the valence shell number. The group number is the same as the total number of electrons in the valence shell for “A” elements. Period 2; group 8A = Ne (b) 1s 2 2s 2 2p 6 3s 2 3p 2 Period 3; group 4A = Si (c) 1s 2 2s 2 2p 6 3s 1 Period 3; group 1A = Na (d) 1s 2 2s 2 Period 2; group 2A = Be (e) 1s 2 2s 2 2p 3 Period 2; group 5A = N (f) 1s 2 2s 2 2p 6 3s 2 3p 1 Period 3; group 3A = Al 43. Use the relationship between electron configurations and the periodic table to determine the number of (a) valence-shell electrons in an atom of Bi, (b) electrons in the fourth principal shell of Au, (c) elements whose atoms have five valence-shell electrons, (d) unpaired electrons in an atom of Se, and (e) transition elements in the fifth period. The period number is the valence shell number. The group number is the same as the total number of electrons in the valence shell for “A” elements. (a) 83 Bi is in group VA, so it has five valence shell electrons. (b) 79 Au I don’t know how to do this using the periodic table, but using Aufbau: [Xe]6s 2 4f 14 5d 9 The fourth principal shell = 4s 2 + 4p 6 + 4d 10 + 4f 14 = 32 electrons (c) N, P, As, Sb and Bi (d) 6 valence shell electrons = = two unpaired electrons in Se (e) Ten transition elements in the fifth period Magnetic Properties 45. Which of the following are diamagnetic and which are paramagnetic? Explain. (a) A Sr atom (b) a F atom (c) a V 5+ ion (d) an Al atom (e) a Zn 2+ ion (a) 38 Sr = 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 Diamagnetic because the valence electrons are all paired. (b) 9 F = 1s 2 2s 2 2p 5 Weakly paramagnetic because one of the electrons in the valence shell is unpaired. Chem 161-2007 homework 10 th week 1 ↑↓ ↑↓
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(c) 23 V 5+ = 1s 2 2s 2 2p 6 3s 2 3p 6 Diamagnetic because all of the electrons in the valence shell are paired (d) 13 Al = 1s 2 2s 2 2p 6 3s 2 3p 1 Paramagnetic because there is an unpaired electron in the valence shell. (e) 30 Zn 2+ = 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 Diamagnetic because all of the electrons in the valence shell are paired. Atomic and Ionic Radii 49. Which member of the following pairs has the larger radius? Explain. (a) Al or S (b) Cl - or Ca 2+ 13 Al 16 S (c) Ba or Sn (d) Na + or K Sulfur has same number of shells, but greater effective nuclear charge (ENC). Therefore, it must be smaller than Al. Therefore, Al is larger. Chem 161-2007 homework 10 th week 2 13+ 3+ 16+ 6+ 2- 2- 2- 8- 8- 3- 6- X X X X X X
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17 Cl - 20 Ca 2+ Ca 2+ and Cl - have the same number of principal shells; however, Ca 2+ has a greater ENC, so is smaller; therefore, Cl - is larger. 56
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This homework help was uploaded on 04/12/2008 for the course CHEM 161 taught by Professor Vacillian during the Fall '08 term at Rutgers.

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#Chem 161-2007 Homework 10th week - Chem 161-2007 10th Week...

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