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General Chemistry Principles, Patterns, and Applications, 2011

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11.<br />

12.<br />

13.<br />

14.<br />

N U M E R I C A L PR O BL E M S<br />

1. Plot the ionic charge versus ionic radius using the following data for Mo: Mo 3+ , 69 pm; Mo 4+ , 65 pm; <strong>and</strong><br />

Mo 5+ , 61 pm. Then use this plot to predict the ionic radius of Mo 6+ . Is the observed trend consistent with the<br />

general trends discussed in the chapter? Why or why not?<br />

2. Internuclear distances for selected ionic compounds are given in the following table.<br />

a. If the ionic radius of Li + is 76 pm, what is the ionic radius of each of the anions?<br />

LiF LiCl LiBr LiI<br />

Distance (pm) 209 257 272 296<br />

b. What is the ionic radius of Na + ?<br />

NaF NaCl NaBr NaI<br />

Distance (pm) 235 282 298 322<br />

3. Arrange the gaseous species Mg 2+ , P 3− , Br − , S 2− , F − , <strong>and</strong> N 3− in order of increasing radius <strong>and</strong> justify your<br />

decisions.<br />

[1] Atomic radii are often measured in angstroms (Å), a non-SI unit: 1 Å = 1 × 10 −10 m = 100 pm.<br />

[2] A similar approach for measuring the size of ions is discussed later in this section.<br />

7.3 Energetics of Ion Formation<br />

L E A R N I N G O B JE C T I V E<br />

1. To correlate ionization energies, electron affinities, <strong>and</strong> electronegativities with the<br />

chemistry of the elements.<br />

We have seen that when elements react, they often gain or lose enough electrons to achieve the valence electron<br />

configuration of the nearest noble gas. In this section, we develop a more quantitative approach to predicting such<br />

reactions by examining periodic trends in the energy changes that accompany ion formation.<br />

Saylor URL: http://www.saylor.org/books<br />

Saylor.org<br />

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