Which scientist was the first to arrange the elements in order of increasing atomic number on the periodic table?

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

Answer: (B)

Verified step by step guidance

1. Understand that the question is about the historical development of the periodic table and the arrangement of elements by atomic number.
2. Recall that Dmitri Mendeleev originally arranged elements by increasing atomic mass, not atomic number, and left gaps for undiscovered elements.
3. Recognize that Henry Moseley conducted experiments using X-ray spectra to determine the atomic number of elements, which is the number of protons in the nucleus.
4. Know that Moseley's work led to the reorganization of the periodic table based on increasing atomic number rather than atomic mass, correcting inconsistencies in Mendeleev's table.
5. Conclude that Henry Moseley was the first scientist to arrange the elements in order of increasing atomic number on the periodic table.