Iridium

Iridium,  ₇₇Ir

General properties
Name, seembol	iridium, Ir
Appearance	sillery white
Pronunciation	/ᵻˈrɪdiəm/ i-RID-ee-əm
Iridium in the periodic cairt
Rh ↑ Ir ↓ Mt osmium ← iridium → platinum
Atomic nummer (Z)	77
Group, block	group 9, d-block
Period	period 6
Element category	transeetion metal
Staundart atomic wicht (Ar)	192.217
Electron configuration	[Xe] 4f14 5d7 6s2
per shell	2, 8, 18, 32, 15, 2
Pheesical properties
Phase	solid
Meltin pynt	2739 K ​(2466 °C, ​4471 °F)
Bylin pynt	4701 K ​(4428 °C, ​8002 °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	563 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, 8
Electronegativity	Pauling scale: 2.20
Atomic radius	empirical: 136 pm
Covalent radius	141±6 pm
Miscellanea
Crystal structur	​face-centered cubic (fcc)
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 n Ω·m (at 20 °C)
Magnetic orderin	paramagnetic
Young's modulus	528 GPa
Shear modulus	210 GPa
Bulk modulus	320 GPa
Poisson ratio	0.26
Mohs haurdness	6.5
Vickers haurdness	1760 MPa
Brinell haurdness	1670 MPa
CAS Nummer	7439-88-5
History
Discovery	Smithson Tennant (1803)
First isolation	Smithson Tennant (1803)
Maist stable isotopes o iridium
iso NA hauf-life DM DE (MeV) DP 188Ir syn 1.73 d ε 1.64 188Os 189Ir syn 13.2 d ε 0.532 189Os 190Ir syn 11.8 d ε 2.000 190Os 191Ir 37.3% - (α) 2.0839 187Re 192Ir syn 73.827 d β– 1.460 192Pt ε 1.046 192Os 192m2Ir syn 241 y IT 0.161 192Ir 193Ir 62.7% - (α) 1.0173 189Re 193mIr syn 10.5 d IT 0.080 193Ir 194Ir syn 19.3 h β– 2.247 194Pt 194m2Ir syn 171 d IT - 194Ir
Decay modes in parentheses are predictit, but hae nae yet been observed

Iridium is the chemical element wi seembol Ir an atomic nummer 77. A vera hard, 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 certain molten sauts an halogens is corrosive tae solid iridium, finely dividit iridium dust is a fair bit mair reactive an can be flammable.