The alkali metals all have similar properties to sodium.
##Na## has similar properties to the alkali metals which are ##Li## ##Na## ##K## ##Rb## ##Cs## and ##Fr##. This is because the alkali metals all have one electron in their outer shell. and it is due to this that they all react vigorously with water.
Their reactivity with water increases down the group due to the fact that the outer electron in each atom as you move down the group gets further away from the nucleus of the atom which means that the atom gives up the outer electron much easier so that it can form ions with a ##+1## charge.