the.com/noble gas
The aristocrats of the periodic table, too complete to mingle with the chemical riffraff.
Why nobleFull electron shells mean they rarely bond
Helium escapeIt leaks out of Earth into space forever
Neon glowPure neon shines only red-orange
Radon dangerRadioactive gas seeping into basements worldwide
Late discoveryArgon found in air in 1894