Protons, Neutron, Electron can be further divided into what????

Dear student,
They are not further divided but they can be broken down.Electrons are not composed of constituent particles, so it can not be broken down any farther. Protons and neutrons are a bit different. They are made of quarks, three a piece. The proton is made of two 'up' quarks and a 'down' quark. The neutron is made of two 'downs' and one 'up'. There are some other types of quarks, six in all. However, due to something called 'color isolation', quarks can not exist on their own. They can only be found as part of combined particles called hadrons (of which protons and neutrons are the most common examples). So it is not like you can break a proton into smaller parts. Those smaller parts can only exist when put together.

I appreciate your curiosity. You will study more about this in your higher classes.