If there is a Na and cl in solid form , There will be atoms inside of them.How do they lose electrons ?.We know solid body has a structure and covering.Just like you can touch is the covering of table that is its outer part.Do we touch the electrons or the atom as we touch a body?.When a body loses electrons from a body,does it mean it loses a part of its structure and when it gains , does it gain some part of other structure body.How does this process happen?
I can't present you a movie of electron interactions, but maybe a fuzzy picture. Imagine a metal body (start with copper): the atoms are held in a solid structure - in a sea of electrons! Those loose electrons can be pushed around easily, so we can make wires out of copper and transmit electricity thru them. If you put two different metals together, the sea "levels" will even out, and a potential will develop between the two metals. But I digress.
Imagine your sodium clump. It has the same sort of firm atomic structure, held together by this sea of electron density which we could push around if we made wires out of it. Well, we do make wires out of sodium, but not for transmitting electricity. We make the wires for dehydrating solvents like benzene.
Now the non-metals, like chlorine gas, hold onto their electrons more tightly - no sea there. Sort of like dry land. Put a chlorine molecule next to the clump of sodium (or a copper wire!), and all of a sudden, the molecule realizes (well, it would, if it had a brain) that it would be more stable if it just split and each chlorine atom grabbed an electron from this sea in the metal. Who would notice? Well, after this occurs a few million times, the chlorine anions find that they can develop a structure by including some sodium cations (sodium atoms without their outermost electron). This results in a greater stability, so the overall process is that a number of sodium atoms transfer their electrons to chlorine molecules to generate sodium chloride crystals. The actual mechanism is probably way more complex - perhaps the chlorine molecule picks up the electron first, then gets bumped and falls apart into a chlorine anion and a chlorine atom which immediately picks up another electron. The actual process can be investigated, but the result is still formation of $NaCl$.
In benzene, the sodium lies at the bottom until a water molecule comes by and lands on the surface. An electron jumps into the water molecule because hydroxide ion is a nice place to hide, but this frees a hydrogen atom. This hydrogen atom rolls around on the sodium surface until it finds another hydrogen atom, and they combine to form a molecule. When enough molecules find each other, they form a bubble and float away. And the process is probably way more intricate.
But overall, electron transfer occurs when two materials get close enough to sense their different electronegativities and conduct/transfer one or more electrons. We separate the process of electron emission and electron absorption in electrolytic cells (batteries).
You can also move electrons out of metals by heating them. The Edison effect is the name for the process of emitting electrons from a heated electrode in a vaccuum - the basis for electron tubes. You can also rub electrons out of certain materials (static electricity) and make sparks (scuff across a rug and touch a light switch). Here the electrons (the outer covering) of one material scrubs off some of the outer covering of the other material - but this is a non-equilibrium situation, and quickly evens out.