Question

The order of the elements in the periodic table is based on the ____________.

A.number of protons in an atom of the element
B.number of neutrons in an atom of each element
C.number of electrons in an atom of each element
D.the order in which they were discovered

Answer 1

A number of protons in an atom of the element

Answer 2

A. # of protons in an atom of the element; the atomic number equals the number of protons