Metallic Bonds Metals can only bond to themselves (same element) Don’t transfer or share electrons (need to lose) Do form lattices in solid state 8-12 metal atoms surround a single atom Crowded so outer energy levels overlap

Electron Sea Model Valence electrons form a “sea” of electrons Free to move = delocalized electrons Forms a metallic cation (+ nucleus) Metallic Bond = cation + delocalized e-

Metallic Properties Moderately high MP – really varies from mercury (-38.9) to tungsten (3422 celsius) High BP Malleable & ductile Durable Good conductors –both heat & electricity Luster (easily absorb & release light) Transition metals = really hard & strong

WHY? Mobile electrons = metal’s properties d electrons = make transitions metals even harder & stronger like chromium, iron and nickel

Alloys Mixture of elements that has metallic properties – usually 2 or more metals Ex: brass, bronze, pewter, stainless steel Why – get good qualities of both elements 2 kinds that are easy to form: substitutional and interstitial

Substitutional Alloys Occur when atoms of different elements are similar in size Atoms of one element are substituted for atoms of another element Ex: copper atoms replace silver atoms to form sterling silver Brass, pewter and 10 carat gold are other examples

Interstitial alloys Occur when one atom is much bigger than the other atom A smaller atom is than used to fill in the spaces or interstices of the bigger atom – like pouring sand into a bucket of gravel Ex: carbon is added to iron and forms carbon steel which makes it harder, stronger and less ductile