
Carbon.
The Big Bang Theory Season 12, Episode 23

Needed bigger CARBON atoms.
The Big Bang Theory Season 3, Episode 14

I don't know. How do CARBON atoms
form a benzene ring?
The Big Bang Theory Season 2, Episode 13

refine it into CARBON dust,
The Big Bang Theory Season 7, Episode 7

Unit cell contains two CARBON atoms.
The Big Bang Theory Season 3, Episode 14