Helium (He)
"The Escapist, a lighter-than-air hero who can lift anything and always makes a high-pitched exit."
A memorable persona to anchor He in your mind.
0.178
Grams per cm³
N/A
Celsius (°C)
140
Radius (pm)
Daily Life Link
The floating balloons at a birthday party.
Discovery & History
Year Discovered
1895
Discovered By
"Pierre Janssen, Norman Lockyer (Detection); Sir William Ramsay, Cleve, & Langlet (Isolation)"
Origin of Name
"The name is derived from the Greek, 'helios' meaning sun, as it was in the sun's corona that helium was first detected."
Technical Properties
Atomic Mass
4.003 u
Standard State
gas
Boiling Point
-268.928°C
Electron Configuration
1s2
1st Ionization Energy
24.587 eV
Electron Affinity
N/A
Oxidation States
"A colorless, odorless, tasteless inert gas."
Did You Know?
It was first discovered not on Earth, but by observing the Sun's spectrum during a solar eclipse in 1868.
It is the only element that cannot be solidified by cooling it at normal atmospheric pressure; it requires immense pressure to freeze.
The high-pitched "chipmunk" voice effect from inhaling helium is because the speed of sound is nearly three times faster in helium than in air.
Helium is a non-renewable resource on Earth, formed by the radioactive decay of uranium and thorium deep underground.