Is sodium a member of the transition elements?
No, it is an Alkali Metal.
All the transition state metals can be found in the clearly marked central portion of the periodic table of elements, but I will tell you that most of the well-known metals, such as iron, copper, gold, lead, zinc, nickel, chromium, platinum, etc., are transition state elements. The only really well known metal that is not a transition state element is aluminum. Other metals such as calcium or sodium are also not transition state elements, but…
Transition elements are called transition elements because the electrons in these elements are not in process of filling valence(outermost ) shell instead they are, in case of d-block elements, in process of filling penultimate shell. and in case of f- block elements, electrons are in process of filling next to the penultimate shell.