Chemistry [hint][solution]

I was absent for too long... better make some out of the box puzzle again

7 18 39 7



SV

It's quite well inside the box 

Hint

SPOILER: Click to show

Try opening a periodic table, and see what those numbers could be...

Thanks for the clue, I didn't see the numbers in your opening post at all

Solution:

SPOILER: Click to show

The numbers 7 18 39 7 represent the atomic number of the elements whose initial letters form the word Naryn. Naryn is a rural Russian city and the spot is near the only river in the city.