Final answer:
The elements on the periodic table are organized by their atomic numbers, not by their mass. The arrangement is based on the idea that elements with similar properties have similar electron configurations.
Step-by-step explanation:
The elements on the periodic table are not arranged by mass, but rather by their atomic numbers. The atomic number of an element corresponds to the number of protons in its nucleus, and it uniquely identifies each element. The periodic table is organized based on the idea that elements with similar properties have similar electron configurations. The arrangement also allows for the identification of trends in properties such as reactivity, electronegativity, and atomic size.