Iridium (Ir)

Very hard and brittle, silvery metallic transition element. It has a yellowish cast to it. Salts of iridium are highly colored. It is the most corrosion resistant metal known, not attacked by any acid, but is attacked by molten salts. There are two natural isotopes of iridium, and 4 radioisotopes, the most stable being Ir-192 with a half-life of 73.83 days. Ir-192 decays into Platinum, while the other radioisotopes decay into Osmium. Iridium is used in high temperature apparatus, electrical contacts, and as a hardening agent for platinumpy. Discovered in 1803 by Smithson Tennant in England. The name comes from the Greek word iris, which means rainbow. Iridium metal is generally non-toxic due to its relative unreactivity, but iridium compounds should be considered highly toxic.

Atomic Number	77
Atomic Weight	192.217
Mass Number	193

Group	9
Period	6
Block	d

Protons	77 p⁺
Neutrons	116 n⁰
Electrons	77 e^-

Properties

Energy
Atomic Radius	135 pm 240 pm
Molar Volume	8.54 cm³/mol
Covalent Radius	122 pm 115 pm 107 pm 141 pm
Metallic Radius	127 pm 136 pm
Ionic Radius	68 pm 62.5 pm 57 pm
Crystal Radius	82 pm 76.5 pm 71 pm
Van der Waals Radius	200 pm 213 pm 236 pm 284 pm
Density	22.5622 g/cm³ 19,000 kg/m³
Proton Affinity
Electron Affinity	1.5638 eV/particle
Ionization Energy	8.96702 eV/particle 17 eV/particle 28 eV/particle 40 eV/particle 57 eV/particle 72 eV/particle 89 eV/particle 105 eV/particle 123 eV/particle 194.8 eV/particle 217 eV/particle 240 eV/particle 264 eV/particle 303 eV/particle 329 eV/particle 356 eV/particle 407 eV/particle 445 eV/particle 472 eV/particle 510 eV/particle 560 eV/particle 610 eV/particle 670 eV/particle 720 eV/particle 770 eV/particle 820 eV/particle 870 eV/particle 920 eV/particle 980 eV/particle 1,030 eV/particle 1,080 eV/particle 1,331 eV/particle 1,381 eV/particle 1,436 eV/particle 1,493 eV/particle 1,548 eV/particle 1,603 eV/particle 1,684 eV/particle 1,739 eV/particle 1,801 eV/particle 1,857 eV/particle 2,083 eV/particle 2,139 eV/particle 2,201 eV/particle 2,258 eV/particle 2,435 eV/particle 2,500 eV/particle 2,656 eV/particle 2,720.4 eV/particle 4,540 eV/particle 4,668 eV/particle 4,806 eV/particle 4,952 eV/particle 5,092 eV/particle 5,229 eV/particle 5,466 eV/particle 5,609 eV/particle 5,765 eV/particle 5,910 eV/particle 6,315 eV/particle 6,441 eV/particle 6,580 eV/particle 6,708 eV/particle 7,274 eV/particle 7,421 eV/particle 7,710 eV/particle 7,850 eV/particle 17,040 eV/particle 17,390 eV/particle 17,770 eV/particle 18,120 eV/particle 20,210 eV/particle 20,650 eV/particle 21,200 eV/particle 21,556.6 eV/particle 86,438.9 eV/particle 88,113.3 eV/particle

Heat of Vaporization	604 kJ/mol
Heat of Fusion	27.61 kJ/mol
Heat of Formation	669 kJ/mol
Electrons
Electron Shells	2, 8, 18, 32, 15, 2

Valence Electrons	2
Electron Configuration	[Xe] 4f¹⁴ 5d⁷ 6s²

Oxidation States	-3, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
Electronegativity	9.96 eV/particle 0.25106 2.2
Electrophilicity	1.872465121129725 eV/particle
Phases
Phase	Solid
Gas Phase
Boiling Point	4,701.15 K
Melting Point	2,719.15 K
Critical Pressure
Critical Temperature
Triple Point
Visual
Color	Silver #ff1493 #175487 #175487
Appearance	silvery white
Refractive Index
Thermodynamic Properties
Thermal Conductivity	147 W/(m K)
Thermal Expansion	0.0000064 1/K
Molar Heat Capacity	25.1 J/(mol K)
Specific Heat Capacity	0.131 J/(g⋅K)
Heat Capacity Ratio (Adiabatic Index)
Electrical Properties
Type	Conductor
Electrical Conductivity	21 MS/m
Electrical Resistivity	0.00000004699999999998 m Ω
Superconducting Point	0.11 K
Magnetism
Type	paramagnetic
Magnetic Susceptibility (Mass)	0.00000000167 m³/Kg
Magnetic Susceptibility (Molar)	0.000000000321 m³/mol
Magnetic Susceptibility (Volume)	0.0000377
Magnetic Ordering
Curie Point
Neel Point
Structure
Crystal Structure	Face Centered Cubic (FCC)
Lattice Constant	3.84 Å
Lattice Angles	π/2, π/2, π/2
Mechanical Properties
Hardness	1,670 MPa 6.5 MPa 1,760 MPa
Bulk Modulus	320 GPa
Shear Modulus	210 GPa
Young Modulus	528 GPa
Poisson Ratio	0.26
Speed of Sound	4,825 m/s
Classification
Category	Transition metals, Transition metals
CAS Group	VIIIA
IUPAC Group	VIII
Glawe Number	62
Mendeleev Number	65
Pettifor Number	65
Geochemical Class	noble metal
Goldschmidt Class	siderophile
Other
Gas Basicity
Dipole Polarizability	54 ± 7 a₀
C6 Dispersion Coefficient	522 a₀
Allotropes
Neutron Cross Section	425
Neutron Mass Absorption	0.081
Quantum Numbers	4F9/2
Space Group	225 (Fm_3m)

Isotopes of Iridium

Stable Isotopes	2
Unstable Isotopes	41
Radioactive Isotopes	40

¹⁶³Ir

Abundance
Relative Atomic Mass	162.994299 ± 0.000429 Da
Mass Number	163
G-Factor
Half Life
Spin	1/2
Quadrupole Moment	0
Discovery Year
Parity	+

¹⁶³Ir Decay Modes

Decay Mode	Intensity
p (proton emission)	%

¹⁶⁴Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	163.991966 ± 0.000339 Da
Mass Number	164
G-Factor
Half Life
Spin	2
Quadrupole Moment
Discovery Year
Parity	-

¹⁶⁴Ir Decay Modes

Decay Mode	Intensity
p (proton emission)	%
α (α emission)	%
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	%

¹⁶⁵Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	164.987552 ± 0.00017 Da
Mass Number	165
G-Factor
Half Life
Spin	1/2
Quadrupole Moment	0
Discovery Year
Parity	+

¹⁶⁵Ir Decay Modes

Decay Mode	Intensity
p (proton emission)	%
α (α emission)	%

¹⁶⁶Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	165.985716 ± 0.000215 Da
Mass Number	166
G-Factor
Half Life	10.5 ± 2.2 ms
Spin	2
Quadrupole Moment
Discovery Year	1981
Parity

¹⁶⁶Ir Decay Modes

Decay Mode	Intensity
α (α emission)	93%
p (proton emission)	7%

¹⁶⁷Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	166.981671973 ± 0.000019694 Da
Mass Number	167
G-Factor
Half Life	29.3 ± 0.6 ms
Spin	1/2
Quadrupole Moment	0
Discovery Year	1981
Parity	+

¹⁶⁷Ir Decay Modes

Decay Mode	Intensity
α (α emission)	43.5%
p (proton emission)	38.6%
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	%

¹⁶⁸Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	167.979960978 ± 0.000059277 Da
Mass Number	168
G-Factor
Half Life	230 ± 50 ms
Spin	2
Quadrupole Moment
Discovery Year	1978
Parity

¹⁶⁸Ir Decay Modes

Decay Mode	Intensity
α (α emission)	100%
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	%
β⁺ p (β⁺-delayed proton emission)	%

¹⁶⁹Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	168.976281743 ± 0.00002502 Da
Mass Number	169
G-Factor
Half Life	353 ± 4 ms
Spin	1/2
Quadrupole Moment	0
Discovery Year	1978
Parity	+

¹⁶⁹Ir Decay Modes

Decay Mode	Intensity
α (α emission)	53%
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	%

¹⁷⁰Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	169.975113 ± 0.000109 Da
Mass Number	170
G-Factor
Half Life	910 ± 150 ms
Spin	3
Quadrupole Moment
Discovery Year	1977
Parity	-

¹⁷⁰Ir Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	%
α (α emission)	5.2%

¹⁷¹Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	170.97164552 ± 0.000041295 Da
Mass Number	171
G-Factor
Half Life	3.1 ± 0.3 s
Spin	1/2
Quadrupole Moment	0
Discovery Year	1967
Parity	+

¹⁷¹Ir Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	%
α (α emission)	15%

¹⁷²Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	171.970607035 ± 0.000034785 Da
Mass Number	172
G-Factor
Half Life	4.4 ± 0.3 s
Spin	3
Quadrupole Moment
Discovery Year	1967
Parity	-

¹⁷²Ir Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	98%
α (α emission)	2%

¹⁷³Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	172.967505477 ± 0.000011316 Da
Mass Number	173
G-Factor
Half Life	9 ± 0.8 s
Spin	1/2
Quadrupole Moment	0
Discovery Year	1967
Parity	+

¹⁷³Ir Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	96.5%
α (α emission)	3.5%

¹⁷⁴Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	173.966949939 ± 0.000012046 Da
Mass Number	174
G-Factor
Half Life	7.9 ± 0.6 s
Spin	2
Quadrupole Moment
Discovery Year	1967
Parity	+

¹⁷⁴Ir Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	99.5%
α (α emission)	0.5%

¹⁷⁵Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	174.964149519 ± 0.000013295 Da
Mass Number	175
G-Factor
Half Life	9 ± 2 s
Spin	1/2
Quadrupole Moment	0
Discovery Year	1967
Parity	+

¹⁷⁵Ir Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	99.15%
α (α emission)	0.85%

¹⁷⁶Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	175.963626261 ± 0.000008679 Da
Mass Number	176
G-Factor
Half Life	8.7 ± 0.5 s
Spin	3
Quadrupole Moment
Discovery Year	1967
Parity	+

¹⁷⁶Ir Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	96.9%
α (α emission)	3.1%

¹⁷⁷Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	176.9613015 ± 0.000021213 Da
Mass Number	177
G-Factor
Half Life	29.8 ± 1.7 s
Spin	5/2
Quadrupole Moment
Discovery Year	1967
Parity	-

¹⁷⁷Ir Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
α (α emission)	0.06%

¹⁷⁸Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	177.961079395 ± 0.000020204 Da
Mass Number	178
G-Factor
Half Life	12 ± 2 s
Spin	3
Quadrupole Moment
Discovery Year	1972
Parity	+

¹⁷⁸Ir Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹⁷⁹Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	178.959117594 ± 0.000010489 Da
Mass Number	179
G-Factor
Half Life	79 ± 1 s
Spin	5/2
Quadrupole Moment
Discovery Year	1992
Parity

¹⁷⁹Ir Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹⁸⁰Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	179.959229446 ± 0.000023302 Da
Mass Number	180
G-Factor	0.5 ± 0.04
Half Life	1.5 ± 0.1 m
Spin	5
Quadrupole Moment
Discovery Year	1972
Parity	+

¹⁸⁰Ir Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹⁸¹Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	180.957634691 ± 0.000005631 Da
Mass Number	181
G-Factor
Half Life	4.9 ± 0.15 m
Spin	5/2
Quadrupole Moment
Discovery Year	1972
Parity	-

¹⁸¹Ir Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹⁸²Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	181.958076296 ± 0.000022509 Da
Mass Number	182
G-Factor
Half Life	15 ± 1 m
Spin	3
Quadrupole Moment
Discovery Year	1961
Parity	+

¹⁸²Ir Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹⁸³Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	182.956841231 ± 0.000026486 Da
Mass Number	183
G-Factor
Half Life	58 ± 5 m
Spin	5/2
Quadrupole Moment
Discovery Year	1961
Parity	-

¹⁸³Ir Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
α (α emission)	%

¹⁸⁴Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	183.957476 ± 0.00003 Da
Mass Number	184
G-Factor
Half Life	3.09 ± 0.03 h
Spin	5
Quadrupole Moment	2.41 ± 0.03
Discovery Year	1960
Parity	-

¹⁸⁴Ir Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹⁸⁵Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	184.956698 ± 0.00003 Da
Mass Number	185
G-Factor	1.0384 ± 0.0052
Half Life	14.4 ± 0.1 h
Spin	5/2
Quadrupole Moment
Discovery Year	1958
Parity	-

¹⁸⁵Ir Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹⁸⁶Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	185.957946754 ± 0.00001774 Da
Mass Number	186
G-Factor
Half Life	16.64 ± 0.03 h
Spin	5
Quadrupole Moment	-2.55 ± 0.03
Discovery Year	1958
Parity	+

¹⁸⁶Ir Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹⁸⁷Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	186.957542 ± 0.00003 Da
Mass Number	187
G-Factor
Half Life	10.5 ± 0.3 h
Spin	3/2
Quadrupole Moment	0.941 ± 0.011
Discovery Year	1958
Parity	+

¹⁸⁷Ir Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹⁸⁸Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	187.958834999 ± 0.000010116 Da
Mass Number	188
G-Factor
Half Life	41.5 ± 0.5 h
Spin	1
Quadrupole Moment	0.484 ± 0.006
Discovery Year	1950
Parity	-

¹⁸⁸Ir Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%

¹⁸⁹Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	188.958722602 ± 0.0000135 Da
Mass Number	189
G-Factor
Half Life	13.2 ± 0.1 d
Spin	3/2
Quadrupole Moment
Discovery Year	1955
Parity	+

¹⁸⁹Ir Decay Modes

Decay Mode	Intensity
ϵ (electron capture)	100%

¹⁹⁰Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	189.960543374 ± 0.00000147 Da
Mass Number	190
G-Factor	0.01 ± 0.0025
Half Life	11.78 ± 0.1 d
Spin	4
Quadrupole Moment	2.87 ± 0.16
Discovery Year	1947
Parity	-

¹⁹⁰Ir Decay Modes

Decay Mode	Intensity
β⁺ (β⁺ decay; β⁺ = ϵ + e⁺)	100%
e⁺ (positron emission)	0.002%

¹⁹¹Ir

Abundance	37.3 ± 0.2
Relative Atomic Mass	190.960591455 ± 0.000001406 Da
Mass Number	191
G-Factor	0.10013333333333 ± 0.0004
Half Life
Spin	3/2
Quadrupole Moment	0.816 ± 0.009
Discovery Year	1935
Parity	+

¹⁹²Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	191.962602414 ± 0.00000141 Da
Mass Number	192
G-Factor	0.47925 ± 0.0025
Half Life	73.82 ± 0.014 d
Spin	4
Quadrupole Moment	2.15 ± 0.06
Discovery Year	1937
Parity	+

¹⁹²Ir Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	95.24%
ϵ (electron capture)	4.76%

¹⁹³Ir

Abundance	62.7 ± 0.2
Relative Atomic Mass	192.962923753 ± 0.000001425 Da
Mass Number	193
G-Factor	0.10866666666667 ± 0.0004
Half Life
Spin	3/2
Quadrupole Moment	0.751 ± 0.009
Discovery Year	1935
Parity	+

¹⁹⁴Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	193.965075703 ± 0.000001429 Da
Mass Number	194
G-Factor	0.39 ± 0.01
Half Life	19.35 ± 0.07 h
Spin	1
Quadrupole Moment	0.339 ± 0.012
Discovery Year	1937
Parity	-

¹⁹⁴Ir Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

¹⁹⁵Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	194.965976898 ± 0.000001431 Da
Mass Number	195
G-Factor
Half Life	2.29 ± 0.17 h
Spin	3/2
Quadrupole Moment
Discovery Year	1952
Parity	+

¹⁹⁵Ir Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

¹⁹⁶Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	195.968399669 ± 0.000041239 Da
Mass Number	196
G-Factor
Half Life	52 ± 1.1 s
Spin	1
Quadrupole Moment
Discovery Year	1966
Parity

¹⁹⁶Ir Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

¹⁹⁷Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	196.969657217 ± 0.000021588 Da
Mass Number	197
G-Factor
Half Life	5.8 ± 0.5 m
Spin	3/2
Quadrupole Moment
Discovery Year	1952
Parity	+

¹⁹⁷Ir Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

¹⁹⁸Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	197.972399 ± 0.000215 Da
Mass Number	198
G-Factor
Half Life	8.7 ± 0.4 s
Spin	1
Quadrupole Moment
Discovery Year	1973
Parity	-

¹⁹⁸Ir Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

¹⁹⁹Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	198.973807097 ± 0.000044073 Da
Mass Number	199
G-Factor
Half Life	7 ± 5 s
Spin	3/2
Quadrupole Moment
Discovery Year	1993
Parity	+

¹⁹⁹Ir Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

²⁰⁰Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	199.976844 ± 0.00021 Da
Mass Number	200
G-Factor
Half Life	43 ± 6 s
Spin	2
Quadrupole Moment
Discovery Year	2008
Parity	-

²⁰⁰Ir Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%
β⁻ n (β⁻-delayed neutron emission)	%

²⁰¹Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	200.978701 ± 0.000215 Da
Mass Number	201
G-Factor
Half Life	21 ± 5 s
Spin	3/2
Quadrupole Moment
Discovery Year	2008
Parity	+

²⁰¹Ir Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

²⁰²Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	201.982136 ± 0.000322 Da
Mass Number	202
G-Factor
Half Life	11 ± 3 s
Spin	2
Quadrupole Moment
Discovery Year	2008
Parity	-

²⁰²Ir Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	100%

²⁰³Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	202.984573 ± 0.000429 Da
Mass Number	203
G-Factor
Half Life
Spin	3/2
Quadrupole Moment
Discovery Year	2009
Parity	+

²⁰³Ir Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	%

²⁰⁴Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	203.989726 ± 0.000429 Da
Mass Number	204
G-Factor
Half Life
Spin
Quadrupole Moment
Discovery Year	2011
Parity

²⁰⁴Ir Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	%
β⁻ n (β⁻-delayed neutron emission)	%

²⁰⁵Ir

Abundance	Radioactive ☢️
Relative Atomic Mass	204.993988 ± 0.000537 Da
Mass Number	205
G-Factor
Half Life
Spin	3/2
Quadrupole Moment
Discovery Year	2012
Parity	+

²⁰⁵Ir Decay Modes

Decay Mode	Intensity
β⁻ (β⁻ decay)	%
β⁻ n (β⁻-delayed neutron emission)	%

History

Iridium was discovered in 1803 by English chemist Smithson Tennant in London. Chemists who studied platinum dissolved it in aqua regia to create soluble salts and observed a small amount of a dark, insoluble residue. Smithson Tennant analyzed the insoluble residue and concluded that it must contain a new metal. From the Latin word iris meaning rainbow

Discoverers	S.Tenant, A.F.Fourcory, L.N.Vauquelin, H.V.Collet-Descoltils
Discovery Location	England/France
Discovery Year	1804
Etymology (Name Origin)	Latin: iris (rainbow).
Pronunciation	i-RID-i-em (English)

Iridium is considered to be of low toxicity

Iridium is the most corrosion-resistant metal known

Uses

Iridium is used in making crucibles and other equipment that is used at high temperatures. Iridium is also used as a hardening agent in platinum alloys. Its resistance to arc erosion makes iridium alloys ideal for electrical contacts for spark plugs. Radioactive isotopes of iridium are used in radiation therapy for the treatment of cancer. 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.

Sources

Found in gravel deposits with platinum.

Abundance
Abundance in Earth's crust	0.001 mg/kg
Abundance in Oceans
Abundance in Human Body
Abundance in Meteor	0.000054 %
Abundance in Sun	0.0000002 %
Abundance in Universe	0.0000002 %

Nuclear Screening Constants

1	s	1.4881
2	p	4.4624
2	s	20.1102
3	d	13.514
3	p	21.9311
3	s	22.7942
4	d	37.2628
4	f	38.6552
4	p	35.086
4	s	34.152
5	d	58.304
5	p	53.339
5	s	51.1545
6	s	66.4334

Iridium on ChemicalAid

Art & Architecture Thesaurus ID	300380172
Australian Educational Vocabulary ID	scot/3533
Brockhaus Enzyklopädie online ID	iridium
CAS Registry Number	7439-88-5
CPV Supplementary	AA28
ChEBI ID	49666
ChemSpider ID	22367
DSSTOX compound identifier	DTXCID8047636
DSSTox substance ID	DTXSID0064674
Den Store Danske ID	Iridium
Den Store Danske ID	iridium
ECHA Substance Infocard ID	100.028.269
Encyclopedia of China Online Database ID (Second Edition)	242533
Encyclopædia Britannica Online ID	science/iridium
Encyclopædia Universalis ID	iridium
Freebase ID	/m/025rw2y
French Vikidia ID	Iridium
GND ID	4162402-6
Gran Enciclopèdia Catalana ID	0117711
Great Russian Encyclopedia Online ID	2020562
HSDB ID	7067
InChI	InChI=1S/Ir
InChIKey	GKOZUEZYRPOHIO-UHFFFAOYSA-N
KBpedia ID	Iridium
Library of Congress authority ID	sh85068067
MeSH descriptor ID	D007495
NALT ID	47705
Namuwiki ID	이리듐
National Diet Library ID	00564222
National Library of Israel J9U ID	987007560422405171
OmegaWiki Defined Meaning	160503
OpenAlex ID	C528581852
PSH ID	5780
PubChem CID	23924
Quora topic ID	Iridium-metal-1
RxNorm ID	1311131
Store norske leksikon ID	iridium
Treccani ID	iridio
UNII	44448S9773
Wolfram Language entity code	Entity["Mineral", "Iridium"]
WordNet 3.1 Synset ID	14666397-n
YSO ID	39350
ZVG number	8460

Iridium (Ir)

Properties

Isotopes of Iridium

163Ir

163Ir Decay Modes

164Ir

164Ir Decay Modes

165Ir

165Ir Decay Modes

166Ir

166Ir Decay Modes

167Ir

167Ir Decay Modes

168Ir

168Ir Decay Modes

169Ir

169Ir Decay Modes

170Ir

170Ir Decay Modes

171Ir

171Ir Decay Modes

172Ir

172Ir Decay Modes

173Ir

173Ir Decay Modes

174Ir

174Ir Decay Modes

175Ir

175Ir Decay Modes

176Ir

176Ir Decay Modes

177Ir

177Ir Decay Modes

178Ir

178Ir Decay Modes

179Ir

179Ir Decay Modes

180Ir

180Ir Decay Modes

181Ir

181Ir Decay Modes

182Ir

182Ir Decay Modes

183Ir

183Ir Decay Modes

184Ir

184Ir Decay Modes

185Ir

185Ir Decay Modes

186Ir

186Ir Decay Modes

187Ir

187Ir Decay Modes

188Ir

188Ir Decay Modes

189Ir

189Ir Decay Modes

190Ir

190Ir Decay Modes

191Ir

192Ir

192Ir Decay Modes

193Ir

194Ir

194Ir Decay Modes

195Ir

195Ir Decay Modes

196Ir

196Ir Decay Modes

197Ir

197Ir Decay Modes

198Ir

198Ir Decay Modes

199Ir

199Ir Decay Modes

200Ir

200Ir Decay Modes

201Ir

201Ir Decay Modes

202Ir