Metallic character of IA group elements :
1) Alkali metals exhibit many of the physical properties common to metals but their densities lower, than those of other metals.
2) Alkali metals have one electron in their outer shell which is loosely bound.
3) They have largest atomic radii of the elements in their respective periods.
4) The lower ionization energies results in their metallic properties and high re-activities.
5) An alkali metal can easily lose it, valence electron to form positive ion.
6) So they have greater metallic character.
7) The metallic character as we move from top to bottom in group due to addition of another shell, it is easy to loose electron.