1. Chapter 22 Chemistry of the Nonmetals John D. Bookstaver St. Charles Community College Cottleville, MO Lecture Presentation © 2012 Pearson Education, Inc.

2. Chemistry of the Nonmetals Except for hydrogen, the nonmetals are found in the upper right-hand corner of the periodic chart. © 2012 Pearson Education, Inc.

3. Chemistry of the Nonmetals Periodic Trends Within a group, smaller atoms are more likely to form  -bonds because they can get closer to other atoms. © 2012 Pearson Education, Inc.

4. Chemistry of the Nonmetals Periodic Trends As a result, CO 2 contains two  -bonds, and SiO 2 is a network solid with only  -bonds. © 2012 Pearson Education, Inc.

5. Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Chemistry: The Central Science, Eleventh Edition By Theodore E. Brown, H. Eugene LeMay, Bruce E. Bursten, and Catherine J. Murphy With contributions from Patrick Woodward Sample Exercise 22.1 Identifying Elemental Properties Consider the elements Li, K, N, P, and Ne. From this list select the element that (a) is the most electronegative, (b) has the greatest metallic character, (c) can bond to more than four surrounding atoms in a molecule, (d) forms  bonds most readily. Solution Analyze: We are given a list of elements and asked to predict several properties that can be related to periodic trends. Plan: We can use the preceding discussion, particularly the summary in Figure 22.1, to guide us to the answers. Thus, we need first to locate each element in the periodic table. Solve: (a) Electronegativity increases as we proceed toward the upper right portion of the periodic table, excluding the noble gases. Thus, nitrogen (N) is the most electronegative element among those listed. (b) Metallic character correlates inversely with electronegativity—the less electronegative an element, the greater its metallic character. The element with the greatest metallic character is therefore potassium (K), which is closest to the lower left corner of the periodic table. (c) Nonmetals tend to form molecular compounds, so we can narrow our choice to the three nonmetals on the list: N, P, and Ne. To form more than four bonds, an element must be able to expand its valence shell to allow more than an octet of electrons around it. Valence-shell expansion occurs for elements in the third period of the periodic table and below; nitrogen and neon are both in the second period and will not undergo valence-shell expansion. Thus, the answer is phosphorus (P). (d) Nonmetals in the second period form  bonds more readily than elements in the third period and below. There are no compounds known that contain covalent bonds to the noble gas Ne. Thus, the other second-row element, N, is the element from the list that forms  bonds most readily.

6. Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Chemistry: The Central Science, Eleventh Edition By Theodore E. Brown, H. Eugene LeMay, Bruce E. Bursten, and Catherine J. Murphy With contributions from Patrick Woodward Sample Exercise 22.1 Identifying Elemental Properties Consider the elements Be, C, Cl, Sb, and Cs. Select the element that (a) has the lowest electronegativity, (b) has the greatest nonmetallic character, (c) is most likely to participate in extensive  bonding, (d) is most likely to be a metalloid. Answers: (a) Cs, (b) Cl, (c) C, (d) Sb Practice Exercise

7. Chemistry of the Nonmetals Halogens The halogens have outer electron configurations of ns 2 np 5. They have large electron affinities and ionization energies. They tend to accept one electron to form anions. © 2012 Pearson Education, Inc.

8. Chemistry of the Nonmetals Halogens All halogens have a  1 oxidation state. All but fluorine also have positive oxidation states up to +7 when bonded to more electronegative atoms. © 2012 Pearson Education, Inc.

9. Chemistry of the Nonmetals Properties of Halogens Halogens tend to be good oxidizers, due to their electronegativity. They can oxidize anions of halides below them on the periodic chart. © 2012 Pearson Education, Inc.

10. Chemistry of the Nonmetals Properties of Halogens Fluorine has an unusually high reduction potential. It can easily oxidize water: F 2 (aq) + H 2 O(l)  2HF(aq) + 1/2 O 2 (g)E  = 1.80 V © 2012 Pearson Education, Inc.

11. Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Chemistry: The Central Science, Eleventh Edition By Theodore E. Brown, H. Eugene LeMay, Bruce E. Bursten, and Catherine J. Murphy With contributions from Patrick Woodward Sample Exercise 22.4 Predicting Chemical Reactions among the Halogens Write the balanced equation for the reaction, if any, that occurs between (a) I – (aq) and Br 2 (l), (b) Cl – (aq) and I 2 (s). Write the balanced chemical equation for the reaction that occurs between Br – (aq) and Cl 2 (aq). Answer: 2 Br – (aq) + Cl 2 (aq) → Br 2 (aq) + 2 Cl – (aq) Practice Exercise Solution Analyze: We are asked to determine whether a reaction occurs when a particular halide and halogen are combined. Plan: A given halogen is able to reduce anions of the halogens below it in the periodic table. Thus, the smaller (lower atomic number) halogen will end up as the halide ion. If the halogen with smaller atomic number is already the halide, there will be no reaction. Thus, the key to determining whether a reaction will occur is locating the elements in the periodic table. Solve: (a) Br 2 is able to oxidize (remove electrons from) the anions of the halogens below it in the periodic table. Thus, it will oxidize I – (b) Cl – is the anion of a halogen above iodine in the periodic table. Thus, I 2 cannot oxidize Cl – ; there is no reaction.

12. Chemistry of the Nonmetals Uses of Halogens Fluorine reacts to form fluorocarbon compounds used as lubricants, refrigerants and plastics. Teflon is a polymer of fluorocarbons. © 2012 Pearson Education, Inc.

13. Chemistry of the Nonmetals Uses of Halogens Chlorine is the most-used halogen. –HCl –Plastics –Bleaches –Water purification © 2012 Pearson Education, Inc.

14. Chemistry of the Nonmetals Hydrogen Halides Aqueous solutions of HCl, HBr, and HI are, of course, strong acids. HF and HCl can be produced by reacting salts with H 2 SO 4. Br  and I  oxidize too easily, so one must use a weaker oxidizing acid, like H 3 PO 4. © 2012 Pearson Education, Inc.

15. Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Chemistry: The Central Science, Eleventh Edition By Theodore E. Brown, H. Eugene LeMay, Bruce E. Bursten, and Catherine J. Murphy With contributions from Patrick Woodward Sample Exercise 22.5 Writing a Balanced Chemical Equation Write a balanced equation for the formation of hydrogen bromide gas from the reaction of solid sodium bromide with phosphoric acid. Write the balanced equation for the preparation of HI from NaI and H 3 PO 4. Answer: NaI(s) + H 3 PO 4 (l) → NaH 2 PO 4 (s) + HI(g) Practice Exercise Solution Analyze: We are asked to write a balanced equation for the reaction between NaBr and H 3 PO 4 to form HBr and another product. Plan: As in Equation 22.20, a metathesis reaction takes place. (Section 4.2) Let’s assume that only one of the hydrogens of H 3 PO 4 undergoes reaction. (The actual number depends on the reaction conditions.) Thus, the remaining H 2 PO 4 – ion will be associated with the Na + ion as NaH 2 PO 4 among the products of the equation. Solve: The balanced equation is

16. Copyright ©2009 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved. Chemistry: The Central Science, Eleventh Edition By Theodore E. Brown, H. Eugene LeMay, Bruce E. Bursten, and Catherine J. Murphy With contributions from Patrick Woodward END OF TODAY’S NOTES 1.Complete page 957-958 #22.12-22.18 and 22.34- 22.38 (evens only) 2.Read complete PowerPoint for chapter 22 on the website AND/OR read the remainder of chapter 22 (just in case – we only discussed those things directly relevant to AP but it’s useful to know the rest as well) 3.Study for your test on Thursday!! The test covers chapters 6, 7, and 22 as well as the two labs!!