Iridium - Periodic Table of the Elements

FACULTY OF CHEMICAL TECHNOLOGY IN SPLIT
PERIODIC TABLE OF THE ELEMENTS version 1.7


 Ir

English:  Iridium
French: Iridium
Croatian: Iridij
German: Iridium
Italian: Iridio


Atomic number: 77
Group numbers: 9
Period: 6
Standard state (20 °C): solid

Iridium was discovered by Smithson Tennant (England) in 1803. The origin of the name comes from the Latin word iris, meaning rainbow, because its salts are highly colored. It is heavy, brittle, white metal. Unreactive in air, water and acids. Attacked by fused NaOH. Metal ignites and burns readily.

Electronic configuration: [Xe] 4f¹⁴ 5d⁷ 6s²
Relative atomic mass: 192.217(3)
Formal oxidation number: +3 +4

Electronegativities: 2.2
Thermal conductivity: 147 W/(m K)
Electrical resistivity (20 °C): 5.3 μΩcm

Atomic radius: 135.7 pm
Density (g/dm3): 22420 (290 K) 
20000 (m.p.)
Molar volume (cm3/mol): 8.57 (290 K) 
8.74 (m.p.)

Melting point: 2446 °C
Boiling point: 4428 °C
Critical temperature: 7527 °C

Heat of fusion: 26.4 kJ/mol
Heat of vaporization: 612.1 kJ/mol
Heat of atomization: 664.34 kJ/mol

Iridium is found in gravel deposits with platinum. Used with osmium to tip gold pen points, to make crucible and special containers. Also to make alloys used for standard weights and measures and heat-resistant alloys. Also as hardening agent for platinum. The price of 99.95 % pure iridium sponge is 829.60 € for 10 g. 76Os <= 77Ir => 78Pt ___________________ If you have comments, corrections or suggestions about this site, please send me a e-mail. Periodic Table of the Elements __________________________________ Last modified: 29.03.2003 Copyright © 1998-2003 by Eni Generalic