Bonding in MetalsNotes 5-4Key Ideas:1. How do the properties of metals and alloys compare?2. How do metal atoms combine?3. How does metallic bonding result in useful properties of metals?

Metals and AlloysAn alloy is a mixture made of two or more elements, at least one of which is a metal. They are generally stronger and less reactive than the pure metals from which they are made.

Physical PropertiesPure gold= shiny and softGold alloys = still shiny but much harder (mixed with copper or silver)Chemical PropertiesPure iron = rusts when exposed to air and waterIron alloy = stronger, resists rust (mixed with one or more other elements to make steel)

Are hard, brittle crystals a characteristic that results from a metallic bond?

No!!!

Metallic Bonding and Metallic Properties

Bonds:Metal atoms combine in regular patterns in which the valence electrons are free to move from atom to atom (think of metal atoms floating in a sea of electrons).Each metal ion is held in place by a metallic bond - an attraction between a positive metal ion and the many electrons surrounding it. (The more valence electrons, the stronger the bond.)5 Properties:Malleability = easily rolled into sheets or made into complex shapesDuctility = easily bent or pulled into wiresLuster = shiny and reflective Electrical Conductivity = conduct electricity easily (because electrons move freely)Thermal Conductivity = conduct heat easily (because electrons move freely)