Atomic Structure (How many times can an atom be divided? How small can it be divided and what is the smallest part known to humans?)

Atoms are the smallest unit of matter that retains the properties of an element, and they cannot be divided into smaller particles while still retaining their chemical identity.

However, atoms are made up of even smaller particles called protons, neutrons, and electrons. Protons and neutrons are located in the nucleus of the atom, while electrons orbit around the nucleus.

While atoms cannot be divided into smaller particles and still retain their chemical identity, they can undergo nuclear reactions, such as fission and fusion, which can break apart or combine the nucleus and release enormous amounts of energy.

The smallest known particle is a matter of ongoing research in the field of particle physics.

Currently, the most fundamental particles known to humans are quarks, leptons, and gauge bosons, which are believed to be indivisible and do not have any internal structure. 

However, it is still possible that even smaller particles exist beyond our current understanding of physics.