General | States | Energies | Oxidation & Electrons |Appearance & Characteristics
Reactions | Other Forms |Radius | Conductivity | Abundance
Encyclopedia Britannica articles


Name Iridium Symbol Ir
atomic number 77 Atomic weight 192.22
Density @ 293 K 22.42 g/cm3 Atomic volume 8.54 cm3/mol
Group Trans. Met. discovered 1804


state (s, l, g) s
melting point 2683.2 K boiling point 4823 K
Heat of fusion 26.10 kJ/mol Heat of vaporization 604.0 kJ/mol
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1st ionization energy 880 kJ/mole electronegativity 2.2
2nd ionization energy kJ/mole electron affinity 151 kJ/mole
3rd ionization energy kJ/mole Specific heat 0.130 J/gK
heat atomization 665 kJ/mole atoms

Oxidation & Electrons

Shells 2,8,18,32,15,2 electron configuration [Xe] 4f14 5d7 6s2
minimum oxidation number -1 maximum oxidation number 6
min. common oxidation no. 0 max. common oxidation no. 4
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Appearance & Characteristics

structure fcc: face-centered cubic color white
uses Pt/Ir sparkplugs toxicity
hardness 6.25 mohs characteristics hard, densest el, inert


reaction with air none reaction with 6M HCl none
reaction with 6M HCl none reaction with 15M HNO3 none
reaction with 6M NaOH none
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Other Forms

number of isotopes 2 hydride(s) none
oxide(s) IrO2 chloride(s) IrCl3


ionic radius (2- ion) pm ionic radius (1- ion) pm
atomic radius 136 pm ionic radius (1+ ion) pm
ionic radius (2+ ion) pm ionic radius (3+ ion) 82 pm
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thermal conductivity 147 J/m-sec-deg electrical conductivity 188.679 1/mohm-cm
polarizability 7.6 A^3


source nickel ores (sulfides) rel. abund. solar system -0.180 log
abundance earth's crust -3 log cost, pure 4200 $/100g
cost, bulk $/100g
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World Wide Web presentation of Chemicool Periodic Table is © Copyright 1996-99 by David D. Hsu. Some data were provided by and used with the permission of JCE Software and is owned and copyright by the Division of Chemical Education, Inc. Additional data were provided by Perkin-Elmer through Peter Lykos of IIT. The information may not be redistributed without the permission of David Hsu or JCE Software.