In the modern period table, the elements are arranged in the increasing order and depending on their physical and chemical properties they are classified into the different groups and atoms.
Alkali metals differ from alkaline earth metal in the atomic structure and their properties as all the alkali metals consist electron in the outer-most shell. And the earth alkaline metals has two outer electron in their shell. So, for achieving the configuration of noble gas the alkali metals loses one electron and the alkaline metal lose two electrons.
