The answer to your question really depends on how much mercury we're talking about.
The first thing you need to do is find mercury on the periodic table. Strangely, mercury is represented by the symbol Hg, which you'll find in row 6/column 12.
There's a lot of information given to you in mercury's box on the periodic table, but right now we're interested in the largest number you see -- 200.59 -- which tells you mercury's atomic mass. The atomic mass tells us two things:
1 atom of mercury has a mass of 200.59 amu (atomic mass units).
1 mole of mercury has a mass of 200.59 grams.
*NOTE: 1 mole of mercury = 6.02×1023 atoms of mercury...that's a lot of atoms!...which is why a mole has a more substantial mass.*