In a way, passing an array as argument always loses a dimension. The reason behind is that, for historical reasons, arrays cannot be directly copied, and thus what is really passed is a pointer. This is a common source of errors for novice programmers.
atomic number represents the protons in atom. As a example hydrogen has one proton and atomic number is 1.
The number of protons in an atom is known as the Atomic Number, which is how the periodic table is organized (they are listed in order of atomic number from left to right). The Mass Number describes the total number of protons and neutrons in the nucleus.