Astable atom that has a large nucleus most likely contains 1. more neutrons than protons. 2.more protons than neutrons. 3.equal numbers of protons and neutrons. 4.changing numbers of protons and neutrons.

answer: atomic mass was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version.

explanation:

originally atomic mass was used to arrange elements on the periodic table from left to right in a row. each column then shows similar properties of elements of a group.

in modern periodic table, the atoms are arranged in increasing atomic number. as atomic number represents the number of protons in an atom which is unique for every atom.