Radium (Ra)
"The Glow-in-the-Dark, a hero from a bygone era who painted the world with a dangerous, radioactive light."
A memorable persona to anchor Ra in your mind.
5.5
Grams per cm³
696
Celsius (°C)
283
Radius (pm)
Daily Life Link
Radium is found in the glowing hands on an antique watch or clock.
Discovery & History
Year Discovered
1898
Discovered By
Marie & Pierre Curie
Origin of Name
"The name is derived from the Latin ''radius'', meaning ray."
Technical Properties
Atomic Mass
[226] u
Standard State
solid
Boiling Point
1500°C
Electron Configuration
[Rn] 7s2
1st Ionization Energy
5.279 eV
Electron Affinity
N/A
Oxidation States
"Radium is a silvery-white, highly radioactive metal."
Did You Know?
It was discovered by Marie and Pierre Curie, who laboriously extracted a tiny amount from tons of uranium ore.
For decades, radium was used in self-luminous paints for the dials of watches, clocks, and aircraft instruments, until the severe health risks to the dial painters became known.
The "Radium Girls" were female factory workers who contracted radiation poisoning from painting watch dials with self-luminous paint.
It is over a million times more radioactive than the same mass of uranium.