Iridium
TRANSITION METAL · GROUP 9 · PERIOD 6
77
Ir
Iridium
192.22
Atomic Data
| Atomic Number | 77 |
| Symbol | Ir |
| Atomic Weight | 192.22 u |
| Density (STP) | 22.56 g/cm³ |
| Melting Point | 2445.85 °C (2719 K) |
| Boiling Point | 4129.85 °C (4403 K) |
| Electronegativity | 2.2 (Pauling) |
| Electron Config. | 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d7 6s2 |
| Oxidation States | +3, +4 |
| Phase at STP | Solid |
| Category | Transition Metal |
| Period / Group | 6 / 9 |
| CAS Number | 7439-88-5 |
Electron Configuration
{{BOHR_SVG}}
[Xe] 4f14 5d7 6s2
| Shell | n | Subshell | Electrons | Cumulative |
|---|---|---|---|---|
| K | 1 | 1s | 2 | 2 |
| L | 2 | 2s | 2 | 4 |
| L | 2 | 2p | 6 | 10 |
| M | 3 | 3s | 2 | 12 |
| M | 3 | 3p | 6 | 18 |
| M | 3 | 3d | 10 | 28 |
| N | 4 | 4s | 2 | 30 |
| N | 4 | 4p | 6 | 36 |
| N | 4 | 4d | 10 | 46 |
| N | 4 | 4f | 14 | 60 |
| O | 5 | 5s | 2 | 62 |
| O | 5 | 5p | 6 | 68 |
| O | 5 | 5d | 7 | 75 |
| P | 6 | 6s | 2 | 77 |
| Total | 77 | 77 | ||
Isotopes of Iridium
Iridium has two naturally occurring stable isotopes. The most abundant is ¹⁹³Ir, comprising 62.7% of all naturally occurring Iridium.
| Isotope | Symbol | Protons | Neutrons | Abundance | Stability |
|---|---|---|---|---|---|
| Iridium-191 | ¹⁹¹Ir | 77 | 114 | 37.3 | Stable |
| Iridium-193 | ¹⁹³Ir | 77 | 116 | 62.7 | Stable |
Abundance & Occurrence
Iridium is present in Earth's crust at approximately 0.001 ppm by mass and at approximately 0.2 ppm by mass throughout the universe.
Earth's Crust (ppm by mass)
Iridium
0.001 ppm
Silicon (ref.)
277,000 ppm
Oxygen (ref.)
461,000 ppm
Universe (ppm by mass)
Iridium
0.2 ppm
Helium (ref.)
230,000 ppm
Hydrogen (ref.)
739,000 ppm
Discovery & History
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Safety & Handling
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Iridium in the Real World
Real-World Uses
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Downloadable Resources
Free periodic table reference sheets for classrooms, study sessions, and laboratory use.