Helium has
an atomic number of two.
The Big Bang Theory Season 7, Episode 3
Hey, in your super-cooled
HELIUM experiments,
The Big Bang Theory Season 9, Episode 16
You and Sheldon already came up
with your superfluid HELIUM model.
The Big Bang Theory Season 9, Episode 16
Not quite accurate.
The Macy's balloons are filled with HELIUM...
The Big Bang Theory Season 4, Episode 24