GENERAL PROPERTIES
NAME, SYMBOL,NUMBER palladium, Pd, 46
PRONUNCIATION /pəˈleɪdiəm/
pə-lay-dee-əm
ELEMENT CATEGORY transition metal
GROUP, PERIOD,BLOCK 10, 5, d
STANDARD ATOMIC WEIGHT 106.42
ELECTRON CONFIGURATION [Kr] 4d10
2, 8, 18, 18 

Electron shells of palladium (2, 8, 18, 18)
HISTORY
DISCOVERY William Hyde Wollaston(1803)
FIRST ISOLATION William Hyde Wollaston(1803)
PHYSICAL PROPERTIES
PHASE solid
DENSITY (NEARR.T.) 12.023 g·cm−3
LIQUID DENSITY ATM.P. 10.38 g·cm−3
MELTING POINT 1828.05 K, 1554.9 °C, 2830.82 °F
BOILING POINT 3236 K, 2963 °C, 5365 °F
HEAT OF FUSION 16.74 kJ·mol−1
HEAT OF VAPORIZATION 362 kJ·mol−1
MOLAR HEAT CAPACITY 25.98 J·mol−1·K−1
VAPOR PRESSURE
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 1721 1897 2117 2395 2753 3234
ATOMIC PROPERTIES
OXIDATION STATES 0, +1, +2+4, +6
(mildly basic oxide)
ELECTRONEGATIVITY 2.20 (Pauling scale)
IONIZATION ENERGIES 1st: 804.4 kJ·mol−1
2nd: 1870 kJ·mol−1
3rd: 3177 kJ·mol−1
ATOMIC RADIUS 137 pm
COVALENT RADIUS 139±6 pm
VAN DER WAALS RADIUS 163 pm
MISCELLANEA
CRYSTAL STRUCTURE face-centered cubic 

Palladium has a face-centered cubic crystal structure
MAGNETIC ORDERING paramagnetic[1]
ELECTRICAL RESISTIVITY (20 °C) 105.4 nΩ·m
THERMAL CONDUCTIVITY 71.8 W·m−1·K−1
THERMAL EXPANSION (25 °C) 11.8 µm·m−1·K−1
SPEED OF SOUND(THIN ROD) (20 °C) 3070 m·s−1
YOUNG’S MODULUS 121 GPa
SHEAR MODULUS 44 GPa
BULK MODULUS 180 GPa
POISSON RATIO 0.39
MOHS HARDNESS 4.75
VICKERS HARDNESS 461 MPa
BRINELL HARDNESS 310 MPa
CAS REGISTRY NUMBER 7440-05-3
MOST STABLE ISOTOPES
Main article: Isotopes of palladium
ISO NA HALF-LIFE DM DE(MEV) DP
100Pd syn 3.63 d ε - 100Rh
γ 0.084, 0.074,
0.126
-
102Pd 1.02% 102Pd is stable with 56 neutrons
103Pd syn 16.991 d ε - 103Rh
104Pd 11.14% 104Pd is stable with 58 neutrons
105Pd 22.33% 105Pd is stable with 59 neutrons
106Pd 27.33% 106Pd is stable with 60 neutrons
107Pd trace 6.5×106y β 0.033 107Ag
108Pd 26.46% 108Pd is stable with 62 neutrons
110Pd 11.72% >6×1017y ββ
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Palladium

Palladium is a chemical element with the chemical symbol Pd and an atomic number of 46. It is a rare and lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after theepithet of the Greek goddess Athena, acquired by her when she slew Pallas. Palladium, platinum, rhodium, ruthenium, iridium andosmium form a group of elements referred to as the platinum group metals (PGMs). These have similar chemical properties, but palladium has the lowest melting point and is the least dense of them.

Over half of the supply of palladium and its congener platinum goes into catalytic converters, which convert up to 90% of harmful gases from auto exhaust (hydrocarbons, carbon monoxide, and nitrogen dioxide) into less-harmful substances (nitrogen, carbon dioxide and water vapor). Palladium is also used in electronics, dentistry, medicine, hydrogen purification, chemical applications, groundwater treatment and jewelry. Palladium plays a key role in the technology used for fuel cells, which combine hydrogen and oxygen to produce electricity, heat, and water.

Ore deposits of palladium and other PGMs are rare, and the most extensive deposits have been found in the norite belt of theBushveld Igneous Complex covering the Transvaal Basin in South Africa, the Stillwater Complex in Montana, United States, theThunder Bay District of Ontario, Canada, and the Norilsk Complex in Russia. Recycling is also a source of palladium, mostly from scrapped catalytic converters. The numerous applications and limited supply sources of palladium result in the metal attracting considerable investment interest.