The nineteenth century chemists arranged elements in the periodic table according to increasing
A) atomic number.
B) number of electrons.
C) atomic mass.
D) number of neutrons.
E) nuclear binding energy.

Question

Quizplus · Accepted Answer

Nineteenth-century chemists, including Dmitri Mendeleev who is credited with the first widely recognized periodic table, arranged elements according to increasing atomic mass. This was before the discovery of protons, neutrons, and the concept of atomic number.

The Nineteenth Century Chemists Arranged Elements in the Periodic Table