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