How were atom bombs made before the first atom was observed by electron microscope? How were atom bombs made before the first atom was observed by electron microscope?
Give a brief history regarding my question please?
 A: The existence of atoms had already been established in terms of behavior of many atoms all together.
Atomic bombs used many atoms together not each one by itself - you also don't need to see an atom split for an atomic bomb to work just like you don't need to see the chemical processes in your body turning food into energy to eat a nice meal.
You don't need to be able to see the individual bits of something to understand it in terms of the bits.
A: To make an atomic bomb, as well as a nuclear reactor, you do not need just the concept of atom, but also the one of radioactive decay, neutron moderation, chain reaction. You also need to be able to compute a critical mass.
Still all of these are concepts: you do not need a direct observation in order to master them, you can just deduce them trying to explain various phenomena that you are able to observe with the available technology.
Important steps through the understanding of these mechanism were achieved by the "via Panisperna boys", a group of young scientists led by Enrico Fermi. You may also find a movie about their short, but very fruitful activity in the field.
