Assertion: electron's number | /r/HasProperty | proton
Facets:
value: collectively
type: DEGREE
Source sentences:
text: The mass number of an isotope is the total number of nucleons (neutrons and protons collectively).
text: In the early 1930s only a small number of subatomic particles were known to exist—the proton, neutron, electron, photon and, indirectly, the neutrino.