proton
Copy
https://doi.org/10.1351/goldbook.P04906
nuclear particle of charge number +1, spin quantum number 1/2 and rest mass of 1.007 276 470 12 u.
See also:
protium
Source:
Green Book, 2
nd
ed., p. 93 (https://goldbook.iupac.org/files/pdf/green_book_2ed.pdf)