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1 METALS Bonds and Properties Alloys Pure Elements.

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1 1 METALS Bonds and Properties Alloys Pure Elements

2 2 Some Properties of Metals Low (lowest: Fr) ELECTRONEGATIVITY Low (lowest: Fr) IONIZATION ENERGY Lose e - to form (+) ions Ion FORMATION Solid (except Hg) PHASE at STP Good to Excellent CONDUCTIVITY : HEAT AND ELECTRICITY Malleable & Ductile DEFORMABILITY HIGH LUSTER

3 3 Many metals have high luster Hmmm…. How much is this shiney Gold worth !? 400 ounces (27.5lbs) $ / ounce $664, per bar 12 bars = $7,968,000.00

4 4 Many Metals have high melting points

5 5 Metallic bonding: different from ionic bond Both bond types due to: electrostatic attraction Ionic bond: transfer electrons from one atom to another Metal bonds: valence electrons ROAM FREELY from one metal atom to next sea of mobile electrons accounts for properties of metals Metal bonding

6 6 Why can electrons in metals roam freely about?

7 7 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 electron energy levels to overlap So…

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

9 9 Na 3s 1 overlapping valence electron orbitals

10 10 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”

11 11 This sea of electrons: binds each metal cation to each neighbor’s cation this creates the metal bond

12 12 Metal Properties sea of mobile electrons gives metals some unique properties since electrons move freely from place to place they: ● conduct electricity (flow of electrons) ● conduct heat Accounts for metals being ● malleable and ductile ● and having luster How do electrons do this?

13 13 Electrical Conductivity - Free flow of electrons through the metal +  e- e-  Flow of electrons e - flow from metal through metal wire towards (+) charge; then flow from (-) terminal back into metal

14 14Malleability Metals & non-metals behave very differently when hit with a force such as hammer Metals DEFORM while Non-metals SHATTER Why? Metals have free flowing electrons & nonmetals do not!

15 15 If apply force to metal: metal atoms shift away from force & free electrons bond newly overlapping metal ions together metal is deformed but shift doesn't change metal atoms If apply force to non-metal: like charges align (+) to (+) (-) to (-) which results in shattering due to repulsion Metal Non-Metal

16 16 Deformation of Metals

17 17 As # of electrons that can be delocalized ↑ so does: Hardness and Strength Na has one valence electron that can be delocalized so: - is relatively soft ( can be cut with a butter knife) Mg has two valence 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 (Cr +6 ) is very hard and has high strength

18 18 Alloys mixture of elements that have metallic properties mixture of elements that have metallic properties mixture can be adjusted to get desired properties mixture can be adjusted to get desired properties substitutional and interstitial alloy (depends on sizes of elements – same or different size) substitutional and interstitial alloy (depends on sizes of elements – same or different size)

19 19 Common alloys Brass: Cu & Zn Bronze: Cu, Sn & Al Pewter: Sn, Pb & Cu Solder: Pb & Sn Rose gold: Cu & Al White gold: Au & Ni, Pd or Pt Sterling silver: Ag & Cu Steel: C & Fe Stainless steel: Cr & Ni


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