Iridium

Iridium is the chemical element wi seembol Ir an atomic nummer 77. A vera haurd, brickle, siller-white transeetion metal o the platinum faimily, iridium is the seicont-densest element (efter osmium) an is the maist corrosion-resistant metal, even at temperaturs as heich as 2000 °C. Tho anerly certaint molten sauts an halogens is corrosive tae solit iridium, finely dividit iridium dust is a fair bit mair reactive an can be flammable.

Iridium, ₇₇Ir

Iridium
Pronunciation	/ɪˈrɪdiəm/ ​(ih-RID-ee-əm)
Appearance	sillery white
Standard atomic weight Ar, std(Ir)	7002192217000000000♠192.217(2)[1]
Iridium in the periodic cairt
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Airn Cobalt Nickel Capper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Siller (element) Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gowd Mercur (element) Thallium Leid (element) Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Ununtrium Flerovium Ununpentium Livermorium Ununseptium Ununoctium Rh ↑ Ir ↓ Mt osmium ← iridium → platinum
Atomic nummer (Z)	77
Group	group 9
Period	period 6
Block	d-block
Element category	Transeetion metal
Electron confeeguration	[Xe] 4f14 5d7 6s2
Electrons per shell	2, 8, 18, 32, 15, 2
Pheesical properties
Phase at STP	solid
Meltin pynt	2719 K ​(2446 °C, ​4435 °F)
Bylin pynt	4403 K ​(4130 °C, ​7466 °F)
Density (near r.t.)	22.56 g/cm3
when liquid (at m.p.)	19 g/cm3
Heat o fusion	41.12 kJ/mol
Heat o vapourisation	564 kJ/mol
Molar heat capacity	25.10 J/(mol·K)
Vapour pressur P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 2713 2957 3252 3614 4069 4659
Atomic properties
Oxidation states	−3, −1, 0, +1, +2, +3, +4, +5, +6, +7, +8, +9[2]
Electronegativity	Pauling scale: 2.20
Ionisation energies	1st: 880 kJ/mol 2nd: 1600 kJ/mol
Atomic radius	empirical: 136 pm
Covalent radius	141±6 pm
Colour lines in a spectral range Spectral lines o iridium
Ither properties
Naitural occurrence	primordial
Creestal structur	​face-centred cubic [[File:face-centred cubic|frameless|alt=Face-centred cubic creestal structur for iridium|upright=0.23|Face-centred cubic creestal structur for iridium]]
Speed o soond thin rod	4825 m/s (at 20 °C)
Thermal expansion	6.4 µm/(m·K)
Thermal conductivity	147 W/(m·K)
Electrical resistivity	47.1 nΩ·m (at 20 °C)
Magnetic orderin	paramagnetic[3]
Magnetic susceptibility	+25.6·10−6 cm3/mol (298 K)[4]
Young's modulus	528 GPa
Shear modulus	210 GPa
Bulk modulus	320 GPa
Poisson ratio	0.26
Mohs haurdness	6.5
Vickers haurdness	1760–2200 MPa
Brinell haurdness	1670 MPa
CAS Nummer	7439-88-5
History
Diskivery an first isolation	Smithson Tennant (1803)
Main isotopes o iridium
Iso­tope Abun­dance Hauf-life (t1/2) Decay mode Pro­duct 188Ir syn 1.73 d ε 188Os 189Ir syn 13.2 d ε 189Os 190Ir syn 11.8 d ε 190Os 191Ir 37.3% stable 192Ir syn 73.827 d β− 192Pt ε 192Os 192m2Ir syn 241 y IT 192Ir 193Ir 62.7% stable 193mIr syn 10.5 d IT 193Ir 194Ir syn 19.3 h β− 194Pt 194m2Ir syn 171 d IT 194Ir
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