Why we cannot see atom,electron or subatomic particles?

There's no such thing as "somtmic" unless you are referring to "subatomic" which refers to anything smaller than an atom, hence the prefix "sub" meaning "under" or "subordinate." Many of the optical instruments that we have don't emit wavelengths of that size except for an electron microscope. This can be compared to shooting pebbles at a rock. The smaller the pebbles, the more detail will be shown by the reflection of those pebbles, rather than if they were larger. And for the matter of "seeing" quarks, forget it, our optics haven't advanced that far yet. We can't see them with our naked eye because they're just simply too small.