Draw the major organic product of each reaction. Indicate the stereochemistry at the stereogenic center. Omit byproducts such as salts. If applicable, expand octets to minimize formal charges.

well in order to answer this question you have to provide more information < 3

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.