08.pdf - 136 CHAPTER 8 THE PERIODIC TABLE SOLUTIONS TO SELECTED TEXT PROBLEMS 8.17(a and(d(b and(f 8.18 Elements that have the same number of valence

08.pdf - 136 CHAPTER 8 THE PERIODIC TABLE SOLUTIONS TO...

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CHAPTER 8: THE PERIODIC TABLE 136 SOLUTIONS TO SELECTED TEXT PROBLEMS 8.17 (a) and (d) ; (b) and (f) ; (c) and (e) . 8.18 Elements that have the same number of valence electrons will have similarities in chemical behavior. Looking at the periodic table, elements with the same number of valence electrons are in the same group. Therefore, the pairs that would represent similar chemical properties of their atoms are: (a) and (d) (b) and (e) (c) and (f) . 8.19 (a) 1 s 2 2 s 2 2 p 5 (halogen) (c) [Ar]4 s 2 3 d 6 (transition metal) (b) [Ar]4 s 2 (alkaline earth metal) (d) [Ar]4 s 2 3 d 10 4 p 3 (Group 5A) 8.20 (a) Group 1A (b) Group 5A (c) Group 8A (d) Group 8B Identify the elements. 8.21 There are no electrons in the 4 s subshell because transition metals lose electrons from the ns valence subshell before they are lost from the ( n 1) d subshell. For the neutral atom there are only six valence electrons. The element can be identified as Cr (chromium) simply by counting six across starting with potassium (K, atomic number 19). What is the electron configuration of neutral chromium? 8.22 You should realize that the metal ion in question is a transition metal ion because it has five electrons in the 3 d subshell. Remember that in a transition metal ion, the ( n 1) d orbitals are more stable than the ns orbital. Hence, when a cation is formed from an atom of a transition metal, electrons are always removed first from the ns orbital and then from the ( n 1) d orbitals if necessary. Since the metal ion has a +3 charge, three electrons have been removed. Since the 4 s subshell is less stable than the 3 d , two electrons would have been lost from the 4 s and one electron from the 3 d . Therefore, the electron configuration of the neutral atom is [Ar]4 s 2 3 d 6 . This is the electron configuration of iron. Thus, the metal is iron . 8.27 Determine the number of electrons, and then “fill in” the electrons as you learned in Chapter 7 (Figure 7.20 and Table 7.3 of the text). (a) 1 s 2 (g) [Ar]4 s 2 3 d 10 4 p 6 (b) 1 s 2 (h) [Ar]4 s 2 3 d 10 4 p 6 (c) 1 s 2 2 s 2 2 p 6 (i) [Kr] (d) 1 s 2 2 s 2 2 p 6 (j) [Kr] (e) [Ne]3 s 2 3 p 6 (k) [Kr]5 s 2 4 d 10 (f) [Ne] 8.28 In the formation of a cation from the neutral atom of a representative element, one or more electrons are removed from the highest occupied n shell. In the formation of a anion from the neutral atom of a representative element, one or more electrons are added to the highest partially filled n shell. Representative elements typically gain or lose electrons to achieve a stable noble gas electron configuration. When a cation
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CHAPTER 8: THE PERIODIC TABLE 137 is formed from an atom of a transition metal, electrons are always removed first from the ns orbital and then from the ( n 1) d orbitals if necessary. (a) [Ne] (e) Same as (c) (b) same as (a). Do you see why? (f) [Ar]3 d 6 . Why isn't it [Ar]4 s 2 3 d 4 ?
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  • Spring '16
  • lee sung chul

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