Show how this amine could have been synthesized by reductive amination of an appropriate aldehyde or ketone. You do not have to consider stereochemistry. Draw both reactants. If there is more than one combination, draw only one. Draw one structure per sketcher. Add additional sketchers using the drop-down menu in the bottom right corner. Separate structures with signs from the drop-down menu.

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.