Section 4 Metallic Bonding Chapter 6 Objectives Describe the electron-sea model of metallic bonding, and explain why metals are good electrical conductors. Explain why metal surfaces are shiny. Explain why metals are malleable and ductile but ionic-crystalline compound are not. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Bonding in Metals 6.4 You have probably seen decorative fences, railings, or weathervanes made of a metal called wrought iron. In this section, you will learn how metallic properties derive from the way that metal ions form bonds with one another. Slide of 39 2 End Show © Copyright Pearson Prentice Hall

The Metallic-Bond Model Section 4 Metallic Bonding Chapter 6 The Metallic-Bond Model In a metal, the vacant orbitals in the atoms’ outer energy levels overlap. This overlapping of orbitals allows the outer electrons of the atoms to roam freely throughout the entire metal. The electrons are delocalized, which means that they do not belong to any one atom but move freely about the metal’s network of empty atomic orbitals. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Metallic Bonds and Metallic Properties 6.4 Bonding in Metals > Metallic Bonds and Metallic Properties The valence electrons of metal atoms can be modeled as a sea of electrons. The valence electrons are mobile and can drift freely from one part of the metal to another. Metallic bonds consist of the attraction of the free-floating valence electrons for the positively charged metal ions. Slide of 19 4 End Show © Copyright Pearson Prentice Hall

The Metallic-Bond Model Section 4 Metallic Bonding Chapter 6 The Metallic-Bond Model These mobile electrons form a sea of electrons around the metal atoms, which are packed together in a crystal lattice. The chemical bonding that results from the attraction between metal atoms and the surrounding sea of electrons is called metallic bonding. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Chapter 6 Metallic Bonding Visual Concepts Chapter 6 Metallic Bonding Click below to watch the Visual Concept. http://my.hrw.com/sh/hc6_003036809x/student/ch06/sec04/vc00/hc606_04_v00fs.htm Visual Concept Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Crystalline Structure of Metals 6.4 Bonding in Metals > Crystalline Structure of Metals Crystalline Structure of Metals How are metal atoms arranged? Slide of 19 7 End Show © Copyright Pearson Prentice Hall

Crystalline Structure of Metals 6.4 Bonding in Metals > Crystalline Structure of Metals These tomatoes have a closed-packed arrangement. Similar arrangements can be found in the crystalline structure of metals. These tomatoes illustrate a pattern called a hexagonal close-packed arrangement. Slide of 19 8 End Show © Copyright Pearson Prentice Hall

Crystalline Structure of Metals 6.4 Bonding in Metals > Crystalline Structure of Metals Metal atoms are arranged in very compact and orderly patterns. Metal atoms crystallize in characteristic patterns. a) Chromium atoms have a body-centered cubic arrangement. b) Gold atoms have a face-centered cubic arrangement. c) Zinc atoms have a hexagonal close-packed arrangement. Inferring Which of these arrangements is the most closely packed? Slide of 19 9 End Show © Copyright Pearson Prentice Hall

Chapter 6 Metallic Bonding Section 4 Metallic Bonding Chapter 6 Metallic Bonding Chemical bonding is different in metals than it is in ionic, molecular, or covalent-network compounds. The unique characteristics of metallic bonding gives metals their characteristic properties, listed below. electrical conductivity thermal conductivity malleability ductility shiny appearance Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Metallic Bonding, continued Section 4 Metallic Bonding Chapter 6 Metallic Bonding, continued Malleability is the ability of a substance to be hammered or beaten into thin sheets. Ductility is the ability of a substance to be drawn, pulled, or extruded through a small opening to produce a wire. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Properties of Metals: Electrical and Thermal Conductivity Visual Concepts Chapter 6 Properties of Metals: Electrical and Thermal Conductivity Click below to watch the Visual Concept. http://my.hrw.com/sh/hc6_003036809x/student/ch06/sec04/vc01/hc606_04_v01fs.htm Visual Concept Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Properties of Metals: Malleability and Ductility Visual Concepts Chapter 6 Properties of Metals: Malleability and Ductility Click below to watch the Visual Concept. http://my.hrw.com/sh/hc6_003036809x/student/ch06/sec04/vc03/hc606_04_v03fs.htm Visual Concept Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Properties of Metals: Surface Appearance Visual Concepts Chapter 6 Properties of Metals: Surface Appearance Click below to watch the Visual Concept. http://my.hrw.com/sh/hc6_003036809x/student/ch06/sec04/vc02/hc606_04_v02fs.htm Visual Concept Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Properties of Substances with Metallic, Ionic, and Covalent Bonds Section 4 Metallic Bonding Chapter 6 Properties of Substances with Metallic, Ionic, and Covalent Bonds Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Metallic Properties * Metallic bond strength varies with the nuclear charge and the number of electrons in the metal’s electron sea. *The enthalpy of vaporization is the amount of energy absorbed as heat when a specified amount of a substance vaporizes at constant pressure. This is a measure of the strength of the metallic bonds. Chapter menu Resources Copyright © by Holt, Rinehart and Winston. All rights reserved.

Alloys Why are alloys important? 6.4 > Bonding in Metals Alloys 17 Slide of 19 17 End Show © Copyright Pearson Prentice Hall

6.4 Bonding in Metals > Alloys Alloys are mixtures composed of two or more elements, at least one of which is a metal. Alloys are important because their properties are often superior to those of their component elements. Slide of 19 18 End Show © Copyright Pearson Prentice Hall

6.4 Bonding in Metals > Alloys Bicycle frames are often made of titanium alloys that contain aluminum and vanadium. Bicycle frames are often made of titanium alloys that contain aluminum and vanadium. Slide of 19 19 End Show © Copyright Pearson Prentice Hall

6.4 Bonding in Metals > Alloys The most important alloys today are steels. Steels have a wide range of useful properties, such as corrosion resistance, ductility, hardness, and toughness. Slide of 19 20 End Show © Copyright Pearson Prentice Hall

Assess students’ understanding of the concepts in Section 6.4. 6.4 Section Quiz. Assess students’ understanding of the concepts in Section 6.4. Continue to: Launch: -or- Section Quiz Slide of 27 End Show © Copyright Pearson Prentice Hall

1. The valence electrons of metals can be modeled as 6.4 Section Quiz. 1. The valence electrons of metals can be modeled as a body-centered cube. octets of electrons. a rigid array of electrons. a sea of electrons. Slide of 39 End Show © Copyright Pearson Prentice Hall

2. In most metals, the atoms are 6.4 Section Quiz. 2. In most metals, the atoms are free to move from one part of the metal to another. arranged in a compact and orderly pattern. placed at irregular locations. randomly distributed. Slide of 39 End Show © Copyright Pearson Prentice Hall

3. Alloys are important because they are pure substances. 6.4 Section Quiz. 3. Alloys are important because they are pure substances. are the ores from which metals can be refined. can have properties superior to those of their components. are produced by the combustion of metals. Slide of 39 End Show © Copyright Pearson Prentice Hall

Online Self-Check Quiz Complete the online Quiz and record answers. Ask if you have any questions about your answers. click here for online Quiz 6.4 (7 questions) You must be in the “Play mode” for the slideshow for hyperlink to work. Slide of 25 End Show © Copyright Pearson Prentice Hall

Bonding in Metals > Concept Map 7 Concept Map 7 Solve the Concept Map with the help of an interactive guided tutorial. Slide of 19 26 End Show © Copyright Pearson Prentice Hall

VIDEOS FOR ADDITIONAL INSTRUCTION Additional Videos for Section 6.4: Metallic Bonding Metallic Bond (2:30) Slide of 28 End Show © Copyright Pearson Prentice Hall