The reactions of group IIA elements are as given below.
1. Water
Alkaline earths (except Be) react with water to liberate hydrogen.
M+2H2O→M(OH)2+H2↑
(M= Mg, Ca, Sr, Ba)
2. Oxygen:
Be, Mg and Ca form oxides
2M+O2Δ−→2MO
(M=Be, Mg and Ca)
Ba, Sr and Ca forms peroxides
M+O2→MO2
(M=Ba, Sr ro Ra)
3. Hydrogen
Alkaline earths (except Be) combine directly with hydrogen to form hydrides.
M+H2Δ−→MH2
(M=Mg,Ca,Sr or Ba)
4. Chlorine.
Alkaline earths combine with chlorine at high temperature to form chlorides.
M+Cl2→MCl2