When iron metal reacts with oxygen, the reaction can form fe2o3. write a balanced chemical equation for this reaction, and find the number of moles of oxygen that are needed to form 6 mol of fe2o3

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.