The best way to learn proper English is to read news report, and watch news on TV. Watching TV shows is a great way to learn casual English, slang words, understand culture reference and humor. If you have already watched these shows then you may recall the words used in the following dialogs.

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

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

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

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

a woman is dividing the ATOMIC weight
of the best noble gas
The Big Bang Theory Season 9, Episode 8