If you mean a gamma photon, it is mass-less.
Atomic mass units
Cobalt is an atomic mass of 58.93 atomic mass units
The Atomic Mass is the mass (weight) of the element measured in atomic mass units (AMU)
Atomic mass
Palladium
The atomic mass (or weight) of silver is 107.8682 amu (atomic mass units)
The atomic mass of magnesium is approximately 24.3 atomic mass units.
The atomic mass of tin is approximately 118.71 atomic mass units.
The Atomic Mass of silver is 107.8682 amu (atomic mass units).
The atomic mass of silver is 107.8682 amu (atomic mass units).
The atomic mass of magnesium is approximately 24.305 atomic mass units (amu).
AMU stands for atomic mass units; the number of units an element has is called its atomic mass. The atomic mass of carbon is exactly 12, by definition.