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 largest subatomic particle (by mass) is the proton. The mass of subatomic particles is measured in atomic mass units (amu). The proton has a mass of 1.007 amu, the neutron has a mass of 1 amu, and the electron has a mass of .0005 amu. The largest subatomic particle (by mass) is the proton.