According to their Wiki pages, the masses of the subatomic particles are:
| Protons | 1.0072764665789(83) Da |
| Neutron | 1.00866491606(40) Da |
| Electron | 5.485799090441(97)×10−4 Da |
The dalton is, by definition, one-twelfth the mass of a 12 C atom (at neutral charge, &c &c), which is composed of six protons, six neutrons, and twelve electrons. But you don’t have to even do the arithmetic: the protons’ and neutrons’ are all greater than 1Da, and there’s twelve of them, plus whatever the electrons weigh.
Where is the extra mass going?