Chemicool

Ir

77

192.22
Iridium
General | States | Energies | Oxidation & Electrons |Appearance & Characteristics
Reactions | Other Forms |Radius | Conductivity | Abundance
Encyclopedia Britannica articles

General

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

States

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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Energies

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

Reactions

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

Radius

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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Conductivity

thermal conductivity 147 J/m-sec-deg electrical conductivity 188.679 1/mohm-cm
polarizability 7.6 A^3

Abundance

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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