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METALLIC ELEMENTS 2/3 of elements 30 commonly used Lhs of periodic table Separated from Nonmetals by the Semimetals B, Si, Ge, As,Te Mostly mined as nonmetallic ores (exception: some noble metals) Criss SEMINON-METALS METALS METALS METALLIC ELEMENTS 2/3 of elements 30 commonly used Lhs of periodic table Alloys: mixtures of two or more metals Steel = Fe + C (or Ni, V, Mo, Cr, Co, W...) tougher, less brittle than iron Brass = Cu + Zn Low T melting; easy to cast Bronze = Cu + Sn Ditto, also harder than Cu; corrosion resistant Solder = Pb + Sn Melts @ low T; joins other metals METALLIC STRUCTURE Metal atoms are positive ions in "sea of electrons" Valence electrons in “cloud” or “conduction band” Mutually shared; Not attached to any particular nucleus e.g,. native metals, Cu Au COVALENT BOND METALLIC BOND IONIC BOND METALS NONMETALS Metallic Bonding Mostly Solids (except H, Hg) Form positive ions Generally high melting point Liquid over hi T range (often >1000°C) Covalent & Ionic Bonding Mostly Gases Form negative ions Low M.P. Liquid over low T range (ELEMENTS) => can melt & cast High electrical conductivity High thermal conductivity (most) Poor electrical conductors Poor thermal conductors except Si, Ge, C (Diamond = highest of all) Special magnetic properties Opaque Metallic luster => ornament; coins Malleable & Ductile Weak to None Transparent or Translucent Dull Brittle cohesion; electron sea => machineable Tough = withstand great strain Brittle w/o breaking, tearing =>many uses High tensile strength Low tensile strength exception: Carbon Nanotubes =strongest fiber Reactive to inert Alkali metals Noble metal: Cu Ag Au = coins Form many compounds NASA Oct 22, 2004 SOLAR ABUNDANCES Solar Photosphere is similar to chondritic meteorites (except for H, He…) Similar to bulk Earth Earth is residue of preexisting stars 1) Large amounts of H (>93 atom %) and He (>6 at.%) Primordial composition; stellar fuel 2) Heavier elements all very rare (∑ ~ 0.1 atom %); essentially trace elements ! 3) Progressive, exponential-like decline with atomic number Z 4) Abundance minimum at Li, Be, B 5) Abundance peaks at C, O, Fe. High for nuclides with Mass # A of multiples of 4 = a particle mass Bulk Earth > 92 wt % Fe, O, Si, Mg {56Fe, 16O, 28Si, 24Mg} 6) Tc (Z=43) and Pm (Z=61) missing- all nuclides radioactive w short half lives 4.2 Ma for 98Tc; but Tc is known in stellar spectra Z => active nucleosynthesis 7) No stable nuclides for Z > 83 (Bi) 8) Even/Odd effect: Harkin's rule. Elements w/ even atomic #’s are more abundant than those w/ odd at. #’s Also true for isotopes of a single element => Nuclear Effect, not a Chemical Effect Confirms compositional measurements by F.W. Clarke (Chief Chemist) & H.S. Washington (USGS 1889 -1930's). Log Abundance 12 H He 10 CO 8 Solar Photosphere data in Lodders & Fegley 1998 Mg Si Fe 6 4 2 Th 0 Tc 0 20 40 U Pm 60 Atomic Number, Z 80 100 0.7 CI Meteorites Concentration, ppm Ce 0.6 data from Loders & Fegley 1998 0.5 Nd 0.4 0.3 Dy Gd La 0.2 0.1 0 Pr Pm 56 Er Sm 58 60 Eu 62 Tb 64 Ho 66 Atomic Number, Z Tm 68 Yb Lu 70 72 30 Sn Isotopes data from Walker et al 1989 25 20 15 105 110 115 120 125 Mass Number A 2.1h 9.6d 105a 0 129d 5 115d 55a 10 18m 4.1h 35m Abundance, Atom % 35 130 ABUNDANT METALS Al OTHER 1.4% 5.4% Mg 14.9% SILICON OXYGEN 14.6% 31.7% IRON 32.0% Bulk Earth Estimate of Kargel & Lewis 1993 ABUNDANT METALS > 0.1 wt. % of Earth's crust ELEMENT BULK EARTH Table 4.2 Henderson Mg Al Si Ti Mn Fe Oxygen 12.7 1.1 15.2 0.05 0.2 34.6 CRUSTAL ABUNDANCE 2.3% 8.2 28.2 0.57 0.095 5.6 29.53 ~45 > 93 % 90 % EARTH: Differentiated planet Crust Mantle (Mg,Fe)SiO4 Core, NiFe uppermost 10-100 km 1215 - 3490 km 3490 -6370 km http://www.ufrgs.br/cebi/terra/estrutura_en.html Log Abundance 12 H He 10 CO 8 Solar Photosphere data in Lodders & Fegley 1998 Mg Si Fe 6 4 2 Th 0 Tc 0 20 40 U Pm 60 Atomic Number, Z 80 100 USGS REE Uses: fiber optics, color cathode ray tubes, catalysts, small hi-strength magnets, magnetic refrigeration, fluorescent tubes, computer disk drives, defense applications USGS