Question

N 1913, Henry Moseley discovered a way to calculate the atomic number for each element and it was determined to arrange the periodic table by atomic number and not atomic mass. Why is atomic number the better way to organize the elements of the periodic table and not organizing by atomic mass?

A: The atomic number and atomic mass are equivalent, so the atomic number is used because it is a smaller number.

B: The atomic number can be different for atoms of the same element, so it makes the patterns of the periodic table more varied.

C: The atomic number can vary based on the number of neutrons the atoms of the same element have, so the atomic mass may not be in order. Also, the atomic mass is unique to each element.

D: The atomic mass can vary based on the number of neutrons the atoms of the same element have, so the atomic mass may not be in order. Also, the atomic number is unique to each element.

Answer 1

Option D is correct

The atomic number is the number of proton present in nucleus of an atom. These are identical to charge number of nucleus. Different atoms having different atomic number which helps them to arrange specifically in the periodic table whereas, the atomic mass is the nubmer of proton + number of neutron which defines the mass of each atom.

The order of atomic mass is not confirmed to be in order because atomic mass depends on number of neutron and the nuber of neutrons are not fixed and thus the arrangement of atoms in periodic table not be done according to atomic mass

Thus, only atomic number is used to arrange the atoms in periodic table