METALS Alloys Pure Elements Bonds and Properties 1

Some Properties of Metals 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) 2

Many metals have high luster Hmmm…. How much is this shiney Gold worth !? 400 ounces (27. 5 lbs) $1738. 35 / ounce $695, 340. 00 per bar 12 bars = $8, 344, 080. 00 3

Many Metals have high melting points 4

Metal bonding Metallic bonding: different from ionic bond Both bond types due to: electrostatic attraction 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 5

Why can electrons in metals roam freely about? 6

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… 7

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

Na 1 s 1 Overlapping orbitals 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” 10

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

Metal Properties 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 How do electrons do this? 12

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

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

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 non-metal: • like charges align (+) & (+) (-) & (-) which results in shattering due to force of repulsion Metal Non-Metal 15

Deformation of Metals 16

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 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 17

Alloys mixture of elements that have metallic properties mixture can be adjusted to get desired properties can be substitutional or interstitial element sizes same size or different sizes 18

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 19