Who organized the periodic table in order of increasing atomic number?

• A. Henry Moseley
• B. John Dalton
• C. Dmitri Mendeleev
• D. Antoine Lavoisier

Answer: (A)

Verified step by step guidance

1. Understand the historical context of the periodic table: Dmitri Mendeleev originally organized the periodic table based on increasing atomic mass and noticed periodic trends in element properties.
2. Recognize the limitation in Mendeleev's arrangement: some elements did not fit perfectly when ordered strictly by atomic mass, leading to inconsistencies.
3. Learn about Henry Moseley's contribution: through X-ray spectroscopy, Moseley discovered that the atomic number (number of protons) is a more fundamental property than atomic mass for organizing elements.
4. Know that Henry Moseley reorganized the periodic table by increasing atomic number, which resolved inconsistencies and better reflected the periodicity of element properties.
5. Conclude that the periodic table as we use it today is organized by increasing atomic number, thanks to Henry Moseley's work.