Mendeleev arranged elements in the periodic table primarily in order of their
A)atomic masses.
B)atomic weights.
C)both atomic weights and atomic numbers.
D)number of neutrons.

Question

Quizplus · Accepted Answer

Mendeleev initially arranged elements in the periodic table in order of increasing atomic mass. Later, with the discovery of isotopes and a better understanding of atomic structure, the table was modified to reflect the order of increasing atomic number, which is closely related to the number of protons in an atom's nucleus. However, Mendeleev's initial arrangement based on atomic mass was a significant breakthrough in understanding the periodic nature of elements.

Mendeleev Arranged Elements in the Periodic Table Primarily in Order