Chemical Properties of Alkaline Earth Metals

The alkaline earth metals are, as a family, less reactive than the alkali metals, though (as with the alkali metals) their reactivity still increases going down the group.

Reactivity toward halogens. All the alkaline earth metals combine directly with a halogen at an elevated temperature to give the corresponding halide: M + X₂ → MX₂ (M = Be, Mg, Ca, Sr, Ba, Ra; X = F, Cl, Br, I). Beryllium's halides need special preparative routes because Be does not combine directly and readily with the halogens the way the rest of the family does: the best route to BeF₂ is the thermal decomposition of (NH₄)₂BeF₄, while BeCl₂ is conveniently made from the oxide, BeO + C + Cl₂ →(600-800 K)→ BeCl₂ + CO. …