Beryllium is a reactive metal, but it's not as reactive as some other elements. Here's a breakdown of what it reacts with:

* Oxygen: Beryllium reacts with oxygen to form beryllium oxide (BeO), a white powder.

* Halogens: Beryllium reacts with halogens like fluorine (F2), chlorine (Cl2), bromine (Br2), and iodine (I2) to form halides like beryllium fluoride (BeF2), beryllium chloride (BeCl2), etc.

* Acids: Beryllium reacts with strong acids like hydrochloric acid (HCl) and sulfuric acid (H2SO4) to produce beryllium salts and hydrogen gas.

* Water: Beryllium reacts very slowly with water at room temperature but will react more readily at higher temperatures.

* Nitrogen: Beryllium reacts with nitrogen at high temperatures to form beryllium nitride (Be3N2).

* Other metals: Beryllium can form alloys with other metals, like copper.

It's important to note: Beryllium is toxic and should be handled with care. Its compounds can also be harmful.