Why does basic character of alkaline earth metals decrease down the group?

Hello Student,

​The basic character decreases down the group because
1. Atomic size

As the atomic size of the element increases, itselectron affinitydecreases consequently. It turns out that when moving vertically in the periodic table, the size of the atom outdoes its electronegativity with regard to basicity.

2. Electron affinity

The ability of an atom “to accept an electron” decreases down the group therefore increases the tendency of the elements to be good Lewis bases (Lewis base is an electron-pair donor). Thus the decrease in electron affinity down the group means the elements donate an electron rather than accepting them.