Question 80

The arrangement of elements on the periodic table is based on their atomic number.

The elements in the periodic table are organized according to their atomic number, which is the number of protons found in the nucleus of an atom of that element.

A) atomic mass

While atomic mass was historically used to arrange elements, it is not the basis for the modern periodic table. Elements with similar atomic masses can be found in different groups, emphasizing that atomic mass alone does not determine an element's position.

B) atomic number

Atomic number is the definitive criterion for the arrangement of elements in the periodic table. Each element is placed in order of increasing atomic number, which correlates directly to the number of protons in its atoms, establishing a clear and consistent organization.

C) number of neutrons

The number of neutrons does not determine the position of an element in the periodic table. Isotopes of an element can have varying neutron counts while still occupying the same position based on their atomic number.

D) density

Density is a physical property that can vary widely among elements and is not used to organize the periodic table. Elements with similar densities can be found in different groups, which further illustrates the inadequacy of density as an organizing principle.

Conclusion

The atomic number is the fundamental basis for the arrangement of elements in the periodic table, making option B the correct choice. All other options fail to accurately reflect the systematic approach to organizing elements, as they do not provide a consistent or universally applicable criterion for arrangement.