When was the periodic law explained by atomic number instead of atomic weight?
Quick Answer
In 1913, Henry Moseley showed that the periodic table should be arranged by atomic number. That solved several inconsistencies in Mendeleev’s original ordering.
The Full Story
Henry Moseley’s work in 1913 transformed the periodic table from a chemical pattern into a structure based on atomic number. By studying X-ray spectra of elements, he showed that the correct ordering property was the number of protons in the nucleus, not atomic weight. This explained odd placements in earlier tables and gave the periodic law its modern form. Moseley’s discovery also helped identify gaps for missing elements with greater precision.
Key Facts
YouTube Angle
Suggested video title for this topic:
"The 1913 discovery that fixed the periodic table"
Was this answer helpful?
Tap a reaction — it helps us pick what to cover next.