Question

why sodium chloride is different from its elements sodium and chlorine?

Answer 1

Here is your answer....

The properties of a compound are entirely different from those of it's constituent elements. So when Sodium and Chlorine mix together then not physically but chemically combine. So Sodium chlorine is different from Sodium and chlorine.....

Hope this answer helps you.......

Answer 2

sodium (cation)and chloride(anion) ions react with each other and form a ionic bond to create a new ionic compound sodium chloride also Known as common salt , with new chemical characteristics .

sodium has and extra electron in it's outermost shell where chlorine needs an election to have a structure of inert gas .
so chlorine takes that extra electron from sodium and chlorine becomes cl^- and sodium becomes Na^+ and create a ionic bond that results in formation of sodium chloride(NaCl).

sodium and chlorine both loses their original property to form this new chemical compound with different chemical properties.