Page 313 - Academic Press Encyclopedia of Physical Science and Technology 3rd InOrganic Chemistry

P1: GPA Final Pages
Encyclopedia of Physical Science and Technology EN010b-481 July 14, 2001 18:45

Noble Metals (Chemistry) 467

TABLE II Properties of Noble Metals a
Properties Platinum Palladium Iridium Rhodium Osmium Ruthenium Gold Silver Units

Atomic Number....... 78 46 77 45 76 44 79 47
Atomic Weight........ 195.09 106.4 192.2 102.905 190.2 101.07 196.967 107.870 Amu
Naturally Occurring 194 190 102 191 103 184 96 197 107
Isotope............. 195 192 104 193 186 98 109
196 105 187 99
198 106 188 100
108 189 101
110 190 102
192 104
Distance Closest
Approach of Atoms . 2.774 2.751 2.715 2.689 2.7341 2.7056 2.884 2.889 Angstrom Units
Crystal Structure ...... FCC FCC FCC FCC HCP HCP FCC FCC
Lattice Constant
a .................. 3.9231 3.8898 3.8394 3.8031 2.7341 2.7056 4.0786 4.0862 Angstrom Units
c/a................. 1.5799 1.5820
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(Pt at 25 C) (Pd at 25 C) (Ir at 26 C) (Rh at 25 C) (Os at 26 C) (Ru at 25 C) (Au at 25 C) (Ag at 25 C)
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4
7
8
7
9
10
9
Valence Electrons ..... 5D 6S 1 4D 10 5D 6S 2 4D 5S 1 5D 6S 2 4D 5S 1 5O 6S 1 4 D 5S 2
Chemical Valence ..... 2, 4 2,4 3, 4 3 4, 6, 8 3,4,6,8 1, 3 1,2,3
6
Magnetic Susceptibility .971 5.23 0.133 .9903 .052 .427 −0.15 −0.181 X10- cgs units/gm
Ionization Potential.... 9.0 8.3 9 7.46 8.7 7.364 9.22 7.542 Electron Volts
Work Function
Thermionic Emission 5.32–5.47 4.99 5.4 4.8 4.7 — 4.25 4.31 Electron volts
Thermal Neutron
Capture
Cross Section....... 8.8 8.0 440 149 15.3 2.56 98.8 63 Barns
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Density at 20 C ....... 21.45 12.02 22.65 12.41 22.61 12.45 19.32 10.49 g/cm 3
Vapor Pressure
Pressure (mm Hg)
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10 −6 ............ 1490 990 1810 1470 2160 1720 953 684 Temp. C
10 −5 ............ 1610 1080 1950 1580 2310 1850 1038 751
10 −4 ............ 1750 1190 2110 1710 2490 1990 1140 828
10 −3 ............ 1910 1320 2290 1860 2690 2150 1260 918
10 −2 ............ 2100 1460 2500 2040 2920 2350 1403 1028
10 −1 ............ 2320 1650 2770 2250 3190 2590 1574 1163
1 ................ 2590 1880 3090 2510 3530 2860 1786 1330
1
10 .............. 2920 2180 3480 2840 3930 3210 2055 1543
2
10 .............. 3340 2570 3980 3250 4440 3630 2412 1825
Melting Point ......... 1772 1554 2447 1963 3045 2310 1064.43 961.93 Temp. C
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Boiling Point ......... 3800 2900 4500 3700 5020 4080 2808 2210 Temp. C
Specific Heat ......... 0.0314 0.0584 0.0307 0.0589 0.0309 0.0551 0.03077 0.0559 cal/gm
Thermal Conductivity
0–100 C ........... 0.17447 0.182 0.354 0.3585 0.208 0.25083 0.743 1.0 cal-cm/sec-cm C
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Linear Coefficient of
6
Thermal Expansion . 9.1 11.6 6.8 8.3 6.1 9.1 14.2 19.68 X10– in/in.- C
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Electrical Resistivity... 9.85 9.93 4.71 4.33 8.12 6.80 2.06 1.59 microhm-cm
Temperature Coefficient
of Electrical
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Resistance.......... 0.003927 0.003802 0.00427 0.00463 0.0042 0.0042 0.004 0.0041 0–100 C., per C
EMF Vs. Pt at 1000 C . — 11.46 12.74 14.10 — 9.74 12.34 10.70 Millivolts
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(at 800 C) (at 700 C)
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Tensile Strength (wire). 32–35,000 47–60,000 300–360,000 200–230,000 — 72,000 30–32,000 42,000 psi
(50% cold (50% cold (hot drawn) (cold drawn) (hot (60% cold (50% cold
worked) worked) swagedbar) worked) worked)
continues