Complex sentence: An elementary particle, such as an electron, quark, or photon, is a particle with no internal structure, whereas a composite particle, such as a proton or neutron, has an internal structure (see figure).
Split into simpler sentences: An elementary particle, such as an electron, quark, or photon, is a particle with no internal structure. Whereas a composite particle, such as a proton or neutron, has an internal structure (see figure).