7.3 Bonding in Metals > 1 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Chapter 7 Ionic and Metallic Bonding 7.1 Ions 7.2 Ionic Bonds and Ionic Compounds 7.3 Bonding in Metals

7.3 Bonding in Metals > 2Objectives 1.Explain metallic bonding and how if influences metal properties. 2.Explain why alloys are important, and discuss important alloys. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

7.3 Bonding in Metals > 3 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. 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 corrosion- resistant material that melts at very high temperatures.

7.3 Bonding in Metals > 4 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. 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.

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

7.3 Bonding in Metals > 6 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. 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.

7.3 Bonding in Metals > 7 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. 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.

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

7.3 Bonding in Metals > 9 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. 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.

7.3 Bonding in Metals > 10 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. How are metals and ionic compounds different? How are they similar? CHEMISTRY & YOU

7.3 Bonding in Metals > 11 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. How are metals and ionic compounds different? How are they similar? CHEMISTRY & YOU Both form crystal structures. different configurations of electrons. The sea of electrons surrounding cations in a metal allows metals to be ductile and malleable. Ionic crystals fracture under pressure.

7.3 Bonding in Metals > 12 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. 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

7.3 Bonding in Metals > 13 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. 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

7.3 Bonding in Metals > 14 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.Alloys Alloys Why are alloys important?

7.3 Bonding in Metals > 15 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.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.

7.3 Bonding in Metals > 16 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.Alloys Alloys are important because their properties are often superior to those of their component elements.

7.3 Bonding in Metals > 17 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.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.

7.3 Bonding in Metals > 18 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. 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

7.3 Bonding in Metals > 19 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. Explain why alloys are important, and list one important alloy.

7.3 Bonding in Metals > 20 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. 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.

7.3 Bonding in Metals > 21 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. 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.

7.3 Bonding in Metals > 22 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. 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

7.3 Bonding in Metals > 23 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. 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. BIG IDEA Bonding and Interactions

7.3 Bonding in Metals > 24 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved. END OF 7.3