Radicals vs atoms having unpaired electrons In organic chemistry course, I read that a radical is an atom, molecule or ion which have unpaired valence electrons.

So does there any difference between chlorine atom or cholrine radical? Also sodium atom contains one valence electron which is unpaired, then does sodium atom is also considered a radical?
Please clarify it.
Yes, a chlorine atom is very much the same as chlorine radical.

With sodium, the two things are technically similar too, but you'll hardly ever encounter a mention of "sodium radical".

Why is that? Well, I guess there is a difference between Na and Cl. A chlorine radical exists in its own right (if only briefly), and is an important intermediate in many reactions. A sodium radical, on the other hand, is pretty much not a thing. Single sodium atoms just don't wander around alone. You may see reactions involving metallic sodium, or ionic salts of sodium, or maybe (not sure about that) some compounds which can pass for covalent, or (unlikely) even $\rm\bf Na^{\pmb-}$... but that would be all.

So it goes.