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Three Types of Bonds • Three types of bonds we need to know: • Ionic bonds – bonds between ions to balance out charges • metal + non-metal • opposite charges attract • Covalent bonds – bonds between two nonmetals sharing (“co”) electrons • Non-metal + non-metal • Metallic bonds - bonds between two metals • metal + metal = Alloy! METALLIC BOND Very strong “bond” between two metals atoms Metallic Bond •Formed between two or more atoms of metallic elements •Electron “cloud” around the metal atoms • Sometimes called a “sea of electrons” Metallic Bonding • Between Metals bound in a “Lattice” • An interlaced structure or pattern… but in 3D! • • Many metal ions occupy a “fixed” space and electrons float inbetween • A “sea of electrons” flows between each of the metal elements A Sea of Electrons Metals Form Alloys • Metals do not actually “bond” with metals • They form Alloys • An Alloy is a solution of a metal in a metal • Examples are steel, brass, bronze and pewter Metallic Bonding Alloys • Metallic bonding accounts for many physical properties of metals: • • • • Strength Ductility Electrical conductivity Luster • Alloys are strong materials! • The atoms in metals have a strong attractive force between them. A lot of energy is required to break the bonds • This gives most metals very high melting and boiling points • And, this means metals have a poor solubility! What are some Alloys? • Bronze = copper + tin • Brass = copper + zinc • Pewter = tin + another metal (such as antimony, silver, lead or bismuth) • Steel is an alloy of iron + another metal (used to produce housewares, buildings, power tools, weaponry and even jewelry…) What do we use Alloys for? • Magnets in loudspeakers • Dental fillings • Friction-reducing coating in machine bearings • Door locks and bolts • Musical instruments, central heating pipes • Metal structures such as bridges • Heavy-duty cookware • Automobile and aircraft body parts • Military equipment • Guns • Nuclear Reactors • Medical Tools • And more!