Question

select the correct answer
how does the modern periodic table arrange elements?
a. by atomic mass
b. by atomic number
c. by number of isotopes
d. by electron mass

Explanation:

The modern periodic table is organized based on the fundamental property of elements that defines their identity and chemical behavior, which is the number of protons in the nucleus (atomic number). Earlier tables used atomic mass, but this was revised to atomic number to fix inconsistencies in element ordering.

Answer:

B. by atomic number