[Tom]

When beryllium reacts with Hydrogen to form BeH2? Both 2s electrons in Be are promoted to the 2p level, thereby forming two identical bonds with the two hydrogen atoms.

This is what I came up with does this sound correct, or does anyone have a better and/or correct explanation for the above reaction?

[Mitch]

I think everything stays s.

[AWK]

Most covalent berylium compounds are linear with sp hybridization, crystalline BeH2
shows tetrahedral hybridization with almost equal Be-H distances.

[Tom]

So neither 2s electron is promoted, and each form a a bond with a hydrogen atom.

[AWK]

For berylium like for boron this is quite complex problem.
In gas phase dimethylberylium (covalent compound) is linear. It means one s electron is promoted on p orbital and form hybridization sp. But solid BeMe2 is tetrahedral with all carbon and berylium atoms involved in multicenter orbitals (sp3 hybridization). This is also a case  for BeH2, but I do not know data for gaseous compound.