SIR WE SAY THAT THE ELECTRONS AER MOVING . BUT ELECTRONS ARE IN THE ATOMS SO IF THE ELECTRONS MOVE THE ATOM HAVE TO MOVE? EXPLAIN IN EASY LANGUAGE

In metals the outwr most shell electrons are very loosely bound to the nucleus.They behave as if they are almost free.They have zigzag motion.So with a little potential difference/push these electrons are displaced and moves towards positive terminal.