All oxygen atoms have 8 protons and all sodium atoms have 11 protons. The nucleon number (or mass number ... of each sub-atomic particle in an atom. The full chemical symbol for an element ...

118 Elements and Their Symbols and Atomic Numbers ... which is based on atomic number rather than atomic mass. This arrangement was established by the British physicist Henry Moseley in 1913 ...

Hence mass number = 40The chemical symbol for argon with its mass number and atomic number is: Isotopes are atoms of an element with the same atomic number but a different mass number, indicating ...