Why alkaline earth metals have smaller ionic and atomic radii as compared to that of alkali metals?

Why alkaline earth metals are harder than alkali metals.

The alkaline earth metals have less electropositive or metallic character as compared to those of alkali metals and their electropositive or metallic character increases down the group. Explain with reasons.

Atomic radii of alkaline earth metals are smaller than the corresponding members of alkali metals. Why?

The alkaline earth metals have smaller size than those of corresponding alkali metals, this is due to

Why are alkaline earth metals harder than alkali metals?