
It's the ATOMIC number for technetium.
The Big Bang Theory Season 6, Episode 8

If you multiply that
by the ATOMIC number of "N"--
The Big Bang Theory Season 7, Episode 3

Now, if you'll excuse me,
the father of the ATOMIC bomb...
The Big Bang Theory Season 4, Episode 3

Atomic magnets?
The Big Bang Theory Season 7, Episode 24

My watch is linked to the ATOMIC clock
in Boulder, Colorado.
The Big Bang Theory Season 1, Episode 10