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Palladium, 46 Palladium Pronunciation (pə-LAY -dee-əm Appearance sillery white Standard atomic weight A r, std (Pd) 7002106420000000000♠ 106.42(1)[ 1] Palladium in the periodic cairt
Atomic nummer (Z ) 46 Group group 10 Period period 5 Block d-block Element category Transeetion metal Electron confeeguration [Kr ] 4d10 Electrons per shell 2, 8, 18, 18 Pheesical properties Phase at STP solit Meltin pynt 1828.05 K (1554.9 °C, 2830.82 °F) Bylin pynt 3236 K (2963 °C, 5365 °F) Density (near r.t. ) 12.023 g/cm3 when liquid (at m.p. ) 10.38 g/cm3 Heat o fusion 16.74 kJ/mol Heat o vapourisation 362 kJ/mol Molar heat capacity 25.98 J/(mol·K) Vapour pressur
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 +2 +4 basic oxide)Electronegativity Pauling scale: 2.20 Atomic radius empirical: 137 pm Covalent radius 139±6 pm Van der Waals radius 163 pm Colour lines in a spectral range Spectral lines o palladiumIther properties Naitural occurrence primordial Creestal structur face-centred cubic (fcc) Speed o soond thin rod 3070 m/s (at 20 °C) Thermal expansion 11.8 µm/(m·K) (at 25 °C) Thermal conductivity 71.8 W/(m·K) Electrical resistivity 105.4 n Ω·m (at 20 °C) Magnetic orderin paramagnetic [ 2] Young's modulus 121 GPa Shear modulus 44 GPa Bulk modulus 180 GPa Poisson ratio 0.39 Mohs haurdness 4.75 Vickers haurdness 461 MPa Brinell haurdness 310 MPa CAS Nummer 7440-05-3 History Diskivery William Hyde Wollaston (1803) First isolation William Hyde Wollaston (1803) Main isotopes o palladium
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Palladium is a chemical element wi the chemical seembol Pd an an atomic nummer o 46. It is a rare an lustrous sillery-white metal discovered in 1803 bi William Hyde Wollaston . He named it efter the asteroid Pallas , that wis itsel named efter the epithet o the Greek goddess Athena , acquired bi her whan she slew Pallas . Palladium, platinum , rhodium , ruthenium , iridium an osmium fairm a group o elements referred tae as the platinum group metals (PGMs). Thae hae seemilar chemical properties, but palladium haes the lawest meltin pynt an is the least dense o thaim.
Ower hauf o the supply o palladium an its congener platinum gangs intae catalytic converters , that convert up tae 90% o harmfu gases frae auto exhaust (hydrocarbons , carbon monoxide , an nitrogen dioxide ) intae less-harmful substances (nitrogen , carbon dioxide an watter vapor ). Palladium is uised in electronics, dentistry , medicine , hydrogen purification, chemical applications, groundwatter treatment an jewelry. Palladium plays a key role in the technology uised for fuel cells , that combine hydrogen an oxygen tae produce electricity, heat, an watter.
Ore deposits o palladium an ither PGMs are rare, an the maist extensive deposits hae been foond in the norite belt o the Bushveld Igneous Complex coverin the Transvaal Basin in Sooth Africae, the Stillwatter Complex in Montana , Unitit States, the Thunder Bay Destrict o Ontario , Canadae, an the Norilsk Complex in Roushie. Recyclin is a soorce o palladium, maistly frae scrapped catalytic converters. The numerous applications an leemitit supply soorces o palladium result in the metal attractin considerable investment interest.
