Every sodium atom has 11 protons and 11 electrons. It has 11 positive charges and 11 negative charges. The mass number of an atom is its total number of protons and neutrons. The atomic number of ...

A study led by Prof. Chen Xurong at the Institute of Modern Physics (IMP) of the Chinese Academy of Sciences (CAS) has provided new insights into the origins of proton mass. From an experimental ...

The atomic number of a chlorine atom is 17 and its mass number is 35. Calculate the number of protons, neutrons and electrons it contains.

Nuclear and particle physics are fundamentally puzzled by the distribution of mass in protons. The three valence quarks that make up a proton's core contribute very little to the proton's mass.