Question

can you tell me what are these sodium,calcium.and what is the meaning of radicles

Answer 1

sodium, calcium are the atoms ..i.e they are not stable still, they want to complete their stable configurancy..
whereas their radicals are the ions.
when atom attain a charge by losing or gaining electrons are known as radicals.
Ca +2 and Na+1 ..that is the valency of calcium is +2 as calcium atom loses its 2 electrons from the outermost shell and forms cation..(the positive form of ion).
and sodium loses its 1 electron and also forms cation.

hope it helps..

:)