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Topic: Metallic Bonding

Topic: Metallic Bonding. Do Now: Name as many properties of ionic compounds you can without looking (then look to make sure you got them all. METALS. Bonds and Properties. Alloys Pure Elements. LUSTER. HIGH. DEFORMABILITY. Malleable & Ductile. CONDUCTIVITY : HEAT AND ELECTRICITY.

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Topic: Metallic Bonding

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  1. Topic: Metallic Bonding Do Now: Name as many properties of ionic compounds you can without looking (then look to make sure you got them all

  2. METALS Bonds and Properties Alloys Pure Elements

  3. LUSTER HIGH DEFORMABILITY Malleable & Ductile CONDUCTIVITY : HEAT AND ELECTRICITY Good to Excellent PHASE at STP Solid (except Hg) Ion FORMATION Lose e- to form (+) ions IONIZATION ENERGY Low (lowest: Fr) ELECTRONEGATIVITY Low (lowest: Fr) REVIEW: Some Properties of Metals

  4. Many metals have high luster Hmmm…. How much is this shiny Gold worth !? 400 ounces (27.5lbs) $1738.35 / ounce $695,340.00 per bar 12 bars = $8,344,080.00

  5. Many Metals have high melting points

  6. Metallic vs Ionic Bonding • Both bond types due to: electrostatic attraction • Metallic bonding: different from ionic bon • Ionic bond: transfer electrons from one atom to another • Metal bonds: electrons ROAM FREELY from one metal atom to next • sea of mobile electrons • accounts for properties of metals

  7. Na 1s1 Na 1s1 Metal bonding • Metals: form organized lattice structures similar to ionic cmpds • adjacent atoms in metal lattice are all same • close proximity of atoms allows outer energy levels to overlap So…

  8. electrons in outer valence shell can move freely through these overlapping energy levels = “sea of mobile electrons”

  9. Metal bonding • Freely moving electrons: • called “delocalized” electrons • allows (+) metal cation to form • Delocalized electrons move freely throughout metal from one cation to next • creates what’s called “the sea of mobile electrons” This sea of electrons: • binds each metal cation to each neighbor cation • this creates the metal bond

  10. sea of mobile electrons gives metals some of their unique properties since electrons move freely from place to place they: • conduct electricity (a flow of electrons) • conduct heat • are malleable and ductile • have luster Metal Properties

  11. Electrical Conductivity - + Flow of electrons e-   e- Free flow of electrons through the metal e- flow from metal through metal wire towards (+) charge; then flow from (-) terminal back into metal

  12. Metals & non-metals behave very differently when hit with a force such as hammer Metals DEFORM: Non-metals SHATTER Metals have free flowing electrons & nonmetals do not! Malleability

  13. Metals DEFORM: Ionic Cmpds SHATTER If force applied to metal: • some metal atoms shift away from force & free electrons simply bond the newly overlapping metal ions together • metal is deformed but shift doesn't change metal atoms If force applied to Ionic compound: • like charges align (+) & (+) (-) & (-) which results in shattering due to force of repulsion

  14. Deformation of Metals Deformation of Metals

  15. As # of electrons that can be delocalized ↑ so does: Hardness and Strength EXAMPLES: • Na has one valence electron that can be delocalized • - is relatively soft ( can be cut with a butter knife) • Mg has two electrons that can be delocalized so: - can still be cut but is much harder than Na • Transition metals have varied # of e-'s that can be delocalized - Chromium is very hard and has high strength

  16. Alloys • mixture of elements that have metallic properties • mixture can be adjusted to get desired properties • can be substitutional • (elements of the same size) • or interstitial • (elements that are different sizes)

  17. Common alloys • White gold: Au & Ni, Pd or Pt • Sterling silver: Ag & Cu • Steel: C & Fe • Stainless steel: Cr & Ni • Brass: Cu & Zn • Bronze: Cu, Sn & Al • Pewter: Sn, Pb & Cu • Solder: Pb & Sn • Rose gold: Cu & Al

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