Assertion: atom's proton | /r/HasProperty | z = 1
Facets:
Source sentences:
text: The number of protons in an element determines its atomic number, Z. Hydrogen is the lightest element and has one proton (Z = 1); uranium is the heaviest naturally occurring element and has 92 protons (Z = 92).
text: the smallest of these may range from so small a charge and mass as a proton (Z = 1), to as large a fragment as argon (Z = 18).