Question

prove that how the valancy of sodium is 1

Answer 1

atomic number of sodium is 11
electronic configuration is 2,8,1
so its valency is 1
the other reason for it that sodium is a metal and metals have tendency to lose electrons.
generally metals have 1 ,2 , 3 valency

Answer 2

as we know that atomic no. of sodium is 11 so we get one in our last shell hence valany of sodium is 1+