\({\%~of~an~element} = \frac{mass~of~an~element~in~the~compound}{relative~formula~mass~M_r} \times 100\) There are six atoms of hydrogen in the compound, so the mass ...

A proton’s mass is more than just the sum of its parts. And now scientists know just what accounts for the subatomic particle’s heft. Protons are made up of even smaller particles called quarks, so ...