Alloys

A friend shows you a beautiful ring that she says is made from pure gold. Your friend is lucky to have such a valuable object. The purity of gold is expressed in units called karats. Gold that is 100 percent pure is labeled 24-karat gold. Gold jewelry that has a 12-karat label is only 50 percent gold. Jewelry that has an 18-karat label is 75 percent gold.

The surface of an object made from pure gold can easily be worn away by contact with other objects or dented because gold is a soft metal. When silver, copper, nickel, or zinc is mixed with gold, the gold is harder and more resistant to wear. These gold mixtures are alloys. An alloy is a mixture of two or more elements, at least one of which is a metal. Alloys have the characteristic properties of metals.


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Table of Contents

Physical Science CHAPTER 1 Science Skills CHAPTER 2 Properties of Matter CHAPTER 3 States of Matter CHAPTER 4 Atomic Structure CHAPTER 5 The Periodic Table CHAPTER 6 Chemical Bonds CHAPTER 7 Chemical Reactions CHAPTER 8 Solutions, Acids, and Bases CHAPTER 9 Carbon Chemistry CHAPTER 10 Nuclear Chemistry CHAPTER 11 Motion CHAPTER 12 Forces and Motion CHAPTER 13 Forces in Fluids CHAPTER 14 Work, Power, and Machines CHAPTER 15 Energy CHAPTER 16 Thermal Energy and Heat CHAPTER 17 Mechanical Waves and Sound CHAPTER 18 The Electromagnetic Spectrum and Light CHAPTER 19 Optics CHAPTER 20 Electricity CHAPTER 21 Magnetism CHAPTER 22 Earth's Interior CHAPTER 23 Earth's Surface CHAPTER 24 Weather and Climate CHAPTER 25 The Solar System CHAPTER 26 Exploring the Universe Skills and Reference Handbook