An ion has 56 protons, 54 electrons, and 81 neutrons. What is its atomic #?

Yes it would be a physical change.

Hello thereone of the following properties was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version. which property fits this description? answer: atomic mass  was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version.