7.3 Bonding in Metals > Chapter 7 Ionic and Metallic Bonding. 7.3 Bonding in Metals. 7.1 Ions 7.2 Ionic Bonds and Ionic Compounds

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2 CHEMISTRY & YOU What are some properties that are unique to metals? Wrought iron is a very pure form of iron that contains trace amounts of carbon. It is a tough, malleable, ductile, and corrosionresistant material that melts at very high temperatures. 2 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

3 Metallic Bonds and Metallic Properties Metallic Bonds and Metallic Properties How can you model the valence electrons of metal atoms? 3 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

4 Metallic Bonds and Metallic Properties Metallic Bonds and Metallic Properties How can you model the valence electrons of metal atoms? Metals consist of closely packed cations and loosely held valence electrons rather than neutral atoms. 4 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

5 Metallic Bonds and Metallic Properties The valence electrons of atoms in a pure metal can be modeled as a sea of electrons. 5 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

6 Metallic Bonds and Metallic Properties The valence electrons of atoms in a pure metal 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. 6 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

7 Metallic Bonds and Metallic Properties Metallic bonds are the forces of attraction between the free-floating valence electrons and the positively charged metal ions. These bonds hold metals together. 7 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

8 Metallic Bonds and Metallic Properties Properties of Metals Metals are good conductors of electric current because electrons can flow freely in the metal. 8 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

9 Metallic Bonds and Metallic Properties Properties of Metals Metals are good conductors of electric current because electrons can flow freely in the metal. As electrons enter one end of a bar of metal, an equal number of electrons leave the other end. 9 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

10 Metallic Bonds and Metallic Properties Properties of Metals Metals are ductile that is, they can be drawn into wires. Force Metal rod Die Wire 10 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

11 Metallic Bonds and Metallic Properties Properties of Metals Metals are ductile that is, they can be drawn into wires. Force Metals are also malleable, which means that they can be hammered or pressed into shapes. Metal rod Die Wire 11 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

12 Metallic Bonds and Metallic Properties Properties of Metals When a metal is subjected to pressure, the metal cations easily slide past one another. Sea of electrons Force Metal cation Metal 12 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

Metallic Bonds and Metallic Properties Properties of Metals When a metal is subjected to pressure, the metal cations easily slide past one another.

13 Metallic Bonds and Metallic Properties Properties of Metals When a metal is subjected to pressure, the metal cations easily slide past one another. Sea of electrons Metal cation Metal Force Force Ionic crystal Nonmetal anion Metal cation Strong repulsions If an ionic crystal is struck with a hammer, the blow tends to push the positive ions close together. The positive ions repel one another, and the crystal shatters. 13 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

15 CHEMISTRY & YOU How are metals and ionic compounds different? How are they similar? Both metals and ionic compounds form crystal structures. However, they have different configurations of electrons. The sea of electrons surrounding cations in a metal allows metals to be ductile and malleable. Ionic crystals will fracture under pressure. 15 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

16 Metallic Bonds and Metallic Properties Crystalline Structure of Metals For spheres of identical size, such as metal atoms, several closely packed arrangements are possible. These Thai oranges illustrate a pattern called a hexagonal close-packed arrangement. 16 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

Chromium The metallic elements sodium, potassium, iron, chromium, and tungsten crystallize

17 Metallic Bonds and Metallic Properties Crystalline Structure of Metals In a body-centered cubic structure, every atom (except those on the surface) has eight neighbors. Chromium The metallic elements sodium, potassium, iron, chromium, and tungsten crystallize in a body-centered cubic pattern. 17 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

Gold Among the metals that form a facecentered cubic structure are copper,

18 Metallic Bonds and Metallic Properties Crystalline Structure of Metals In a face-centered cubic arrangement, every atom has twelve neighbors. Gold Among the metals that form a facecentered cubic structure are copper, silver, gold, aluminum, and lead. 18 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

The pattern is different from the face-centered cubic arrangement.

19 Metallic Bonds and Metallic Properties Zinc Crystalline Structure of Metals In a hexagonal close-packed arrangement, every atom also has twelve neighbors. The pattern is different from the face-centered cubic arrangement. Metals that have a hexagonal closepacked crystal structure include magnesium, zinc, and cadmium. 19 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

20 Which of the following models can describe the valence electrons of metals? A. A body-centered cube B. Octets of electrons C. A rigid array of electrons D. A sea of electrons 20 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

21 Which of the following models can describe the valence electrons of metals? A. A body-centered cube B. Octets of electrons C. A rigid array of electrons D. A sea of electrons 21 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

23 Alloys Alloys Why are alloys important? Alloys are mixtures of two or more elements, at least one of which is a metal. Brass, for example, is an alloy of copper and zinc. 23 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

5 percent copper) is harder and more durable than pure silver, yet it is still soft

25 Alloys Alloys are important because their properties are often superior to those of their component elements. Sterling silver (92.5 percent silver and 7.5 percent copper) is harder and more durable than pure silver, yet it is still soft enough to be made into jewelry and tableware. 25 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

Alloys The most important alloys today are steels. The principal elements in most steels, in addition to iron and carbon, are boron, chromium, manganese, molybdenum, nickel, tungsten, and vanadium.

26 Alloys The most important alloys today are steels. The principal elements in most steels, in addition to iron and carbon, are boron, chromium, manganese, molybdenum, nickel, tungsten, and vanadium. Steels have a wide range of useful properties, such as corrosion resistance, ductility, hardness, and toughness. Stainless Steel 80.6% Fe 18.0% Cr 0.4% C 1.0% Ni 26 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

28 Alloys Alloys can form from their component atoms in different ways. If the atoms of the components in an alloy are about the same size, they can replace each other in the crystal. This type of alloy is called a substitutional alloy. 28 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

29 Alloys Alloys can form from their component atoms in different ways. If the atoms of the components in an alloy are about the same size, they can replace each other in the crystal. This type of alloy is called a substitutional alloy. If the atomic sizes are quite different, the smaller atoms can fit into the interstices (spaces) between the larger atoms. Such an alloy is called an interstitial alloy. 29 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

31 Explain why alloys are important, and list one important alloy. Alloys are important because they often have properties that are superior to those of the elements from which they are made. Stainless steel is an important alloy because of its corrosion resistance. 31 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

32 Key Concepts The valence electrons of atoms in a pure metal can be modeled as a sea of electrons. Alloys are important because their properties are often superior to those of their component elements. 32 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

33 Glossary Terms metallic bond: the force of attraction that holds metals together; it consists of the attraction of free-floating valence electrons for positively charged metal ions alloy: a mixture composed of two or more elements, at least one of which is a metal 33 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

34 BIG IDEA Bonding and Interactions Metals are made up of closely packed cations surrounded by a sea of electrons. The sea-of-electrons model explains why metals are good conductors of electric current and why they are ductile and malleable. 34 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

Properties of Metals and Alloys

Properties of Metals and Alloys 1 of 19 Boardworks Ltd 2016 Properties of Metals and Alloys 2 of 19 Boardworks Ltd 2016 What is the structure of metals? 3 of 19 Boardworks Ltd 2016 Metal particles are