Section Review 8.3 1. Molten lithium is one of the most reactive substances
known, reacting with almost every other element except
the noble gases. Predict the reaction of molten lithium
with each of the following elements if it forms Li, O with
oxygen
a, fluorine
b. sulfur

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.