Question

When the first periodic table of the elements was published, the elements were arranged by atomic mass. Although several elements seemed out of order, later discoveries showed the order to be correct.

Which event most likely helped the development of the periodic table?
Scientists changed the atomic masses to better fit the pattern.
Scientists refused to consider other ways to organize the elements.
New technology was developed that modified the masses.
New information changed the understanding of the atom’s structure.

Answer 1

New information changed the understanding of the atom’s structure.

Explanation: Discoveries such as protons, electrons and isotopes (and Moseley’s work showing atomic number—not mass—determines element identity) explained the apparent mass-order discrepancies and led to the modern periodic table.