Dmitri Mendeleev based the arrangement of elements primarily on which property?

Dmitri Mendeleev based the arrangement of elements primarily on which property?

• A. Atomic weights
• B. Atomic numbers
• C. Electron configurations
• D. Ionization energy

Answer: (A)

Organizing the elements by increasing atomic weight is what Mendeleev used to create his periodic table. He observed that when elements were arranged by mass, their chemical properties appeared to repeat at regular intervals, which allowed him to group similar elements together and notice patterns across periods and groups. He even left gaps for elements that hadn’t been discovered yet, predicting their properties based on these repeating trends. Atomic numbers, which reflect the number of protons, became the later standard after Moseley showed their importance, resolving some inconsistencies that mass alone couldn’t explain. Electron configurations and ionization energy are important characteristics, but they weren’t the organizing rule Mendeleev relied on. So the best answer is arranging the elements by atomic weight.

Organizing the elements by increasing atomic weight is what Mendeleev used to create his periodic table. He observed that when elements were arranged by mass, their chemical properties appeared to repeat at regular intervals, which allowed him to group similar elements together and notice patterns across periods and groups. He even left gaps for elements that hadn’t been discovered yet, predicting their properties based on these repeating trends.

Atomic numbers, which reflect the number of protons, became the later standard after Moseley showed their importance, resolving some inconsistencies that mass alone couldn’t explain. Electron configurations and ionization energy are important characteristics, but they weren’t the organizing rule Mendeleev relied on. So the best answer is arranging the elements by atomic weight.