26.07.2021 Views

General Chemistry Principles, Patterns, and Applications, 2011

General Chemistry Principles, Patterns, and Applications, 2011

General Chemistry Principles, Patterns, and Applications, 2011

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

containing Zn 2+ ? Why or why not? Would you expect Fe or Zn to have the lower third ionization energy?<br />

Why?<br />

4. ♦ Underst<strong>and</strong>ing trends in periodic properties allows us to predict the properties of individual elements. For<br />

example, if we need to know whether francium is a liquid at room temperature (approximately 20°C), we<br />

could obtain this information by plotting the melting points of the other alkali metals versus atomic number.<br />

Based on the data in the following table, would you predict francium to be a solid, a liquid, or a gas at 20°C?<br />

Li Na K Rb Cs<br />

Melting Point (°C) 180 97.8 63.7 39.0 28.5<br />

5. Francium is found in minute traces in uranium ores. Is this consistent with your conclusion? Why or why not?<br />

Why would francium be found in these ores, but only in small quantities?<br />

A N S W E R S<br />

1. Due to its 3s 2 3p 4 electron configuration, sulfur has three common oxidation states: +6, +4, <strong>and</strong> −2. Examples<br />

of each are: −2 oxidation state, the sulfide anion, S 2− or hydrogen sulfide, H 2 S; +4 oxidation state, the sulfite<br />

ion, SO 2− 3 ; +6 oxidation state, the sulfate ion, SO 2− 4 . The sulfate ion would be the best biological oxidant,<br />

because it can accept the greatest number of electrons.<br />

2.<br />

3. Iron(II) has four unpaired electrons, <strong>and</strong> iron(III) has five unpaired electrons. Compounds of Zn 2+ do not<br />

exhibit magnetic behavior, because the Zn 2+ ion has no unpaired electrons. The third ionization potential of<br />

zinc is larger than that of iron, because removing a third electron from zinc requires breaking into the closed<br />

3d 10 subshell.<br />

Chapter 8Ionic versus Covalent Bonding<br />

In Chapter 7 "The Periodic Table <strong>and</strong> Periodic Trends", we described the relationship between the chemical properties<br />

<strong>and</strong> reactivity of an element <strong>and</strong> its position in the periodic table. In this chapter <strong>and</strong> Chapter 9 "Molecular Geometry<br />

<strong>and</strong> Covalent Bonding Models", we describe the interactions that hold atoms together in chemical substances, <strong>and</strong> we<br />

examine the factors that determine how the atoms of a substance are arranged in space. Our goal is to underst<strong>and</strong><br />

how the properties of the component atoms in a chemical compound determine the structure <strong>and</strong> reactivity of the<br />

compound.<br />

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

Saylor.org<br />

672

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!