There's growing evidence ...Fentanyl (or hydromorphone) have a better side effect profile than morphine (remember the vaunted vasodilation is only a side effect) thereby making fentanyl a better choice..
The subatomic particles in the nucleus of a carbon atom are protons and neutrons. The atomic nucleus contains protons and usually neutrons (except for hydrogen-1 (protium) atoms. The number of protons is an element's atomic number and is the same for all atoms of an element. Carbon has atomic number #6#. So all atoms of carbon have #6# protons in their atomic nuclei.
The three basic subatomic particles that comprise an atom are protons, electrons, and neutrons. The historical definition of a subatomic particle was expanded over the past several decades to include elementary particles that are less complex than an atom and cannot be broken down further.