Iridium (Ir)
"The Dinosaur-Slayer, the hero from space whose presence in the Earth's crust is the smoking gun for the asteroid that wiped out the dinosaurs."
A memorable persona to anchor Ir in your mind.
22.56
Grams per cm³
2446
Celsius (°C)
202
Radius (pm)
Daily Life Link
Iridium is found in the tip of a premium, long-lasting spark plug.
Discovery & History
Year Discovered
1803
Discovered By
Smithson Tennant
Origin of Name
"The name is derived from the Greek goddess of the rainbow, Iris."
Technical Properties
Atomic Mass
192.217 u
Standard State
solid
Boiling Point
4428°C
Electron Configuration
[Xe] 4f145d76s2
1st Ionization Energy
9.1 eV
Electron Affinity
N/A
Oxidation States
"Iridium is a very hard, brittle, silvery-white metal."
Did You Know?
It is considered the most corrosion-resistant metal known; it is not attacked by any acid, including aqua regia.
The global discovery of a thin layer of iridium-rich clay in geological strata from 66 million years ago is the key evidence for the massive asteroid impact that led to the extinction of the dinosaurs.
It is the second-densest element, just slightly less dense than osmium.
The tips of high-performance spark plugs are often made with iridium because of its hardness and high melting point.