Chemical Bonds

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 non- metals 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 in- between 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!