Powdered Beryllium burns in air to give

Beryllium is reluctant to burn unless it is in the form of dust or powder. Beryllium has a very strong (but very thin) layer of beryllium oxide on its surface, and this prevents any new oxygen getting at the underlying beryllium to react with it.

But If there is Powdered Beryllium then reaction occur is 

$$\begin{gathered} 2\mathrm{Be}\left(\mathrm{s}\right) + {\mathrm{O}}_2\left(\mathrm{g}\right) \to 2\mathrm{BeO}\left(\mathrm{s}\right) \\ 3 \mathrm{Be} \left(\mathrm{s}\right) + {\mathrm{N}}_2 \to {\mathrm{Be}}_3{\mathrm{N}}_2 \end{gathered}$$