Physical Properties
Density: Li < K < Na < Rb < Cs
Reactivity Li < Na < K < Rb < Cs
I.P. Li > Na > K > Rb > Cs
Melting point Li > Na > K > Rb > Cs
Boiling point Li > Na > K > Rb > Cs
Electropositive character Li < Na < K < Rb < Cs
Photoelectric
effect: Except Li (High I.P.) all elements show this
effect, Cs used in solar cell.