inorganic chemistry - Specifically how dangerous is a 10g chemical sample of pure arsenic and how do you properly dispose of it?

I'm not a chemist. I'm an electrical engineering student and I recently purchased an element collection. The collection came with a 10g arsenic sample. I assumed it wasn't much of a thing because there were no warnings or anything but afterward when I started reading more I became concerned. How dangerous is the really, what precautions must I take in handling the sample, and most importantly how do I properly dispose of this sample?

Thank you

Answer

What you have is a sample of arsenic in its 'metallic' form (it is actually a metalloid). This makes it not as dangerous as you might be imagining. The reason is that As(0) (what you have) is not absorbed easily by the body. What is actually extremely dangerous are soluble forms of arsenic eg. arsenate salts etc. Those are readily absorbed by the body and cause all sort of problems. Arsine ($\ce{ArH3}$) is pretty nasty for example since being a gas is readily absorbed in the lungs.

The above applies for many other compounds, a characteristic example being mercury. We have all heard about how toxic mercury is. However, what most people are not aware is that it is the soluble mercury salts that is the issue here (eg. $\ce{HgCl2}$) and not as much metallic mercury. Actually metallic mercury is very hard to absorb by ingestion or through the skin so if ingested one will most likely survive (according to studies on animals). However, if one ingests the same amount in a soluble salt form (or any other absorbable form, eg $\ce{HgMe2}$) he is in serious trouble (see here: Karen Wetterhahn). The main issue with metallic Hg is its vapors which can again be absorbed so it is not safe to have it in a non confined from (eg, mercury spillage).

Same applies for tin! The metal is (obviously) safe, as well as the salts which are not absorbed by the body. Organotin compounds on the other hand are readily absorbed and extremely dangerous.

Lastly, having been a mineral collector myself many years ago, i used to have a sample too (which i handled with bare hands sometimes something i dont recommend doing) and never had a health issue 20 years now.

In conclusion, i dont think you need to dispose your sample. Keep it in its box and avoid handling it just to be on the safe side as Waylander mentions in his comment. Definitely dont inhale any dust from it although that would be unlikely to happen unless you grind your sample.