Episode 1 of 3
Arrangement by Atomic Weight
- When
- 17 February 1869
- Where
- Saint Petersburg
Mendeleev began arranging elements by atomic weights in February 1869, finding a consistent pattern of recurring properties.
On 17 February 1869, Mendeleev started comparing elements by atomic weights. He arranged 63 elements in columns, noting recurring chemical properties. This arrangement formed the basis of his periodic law, which stated that properties depend on atomic mass.
Sources
- Periodic table Wikipedia, revision of 2026-09-21
- History of the periodic table Wikipedia, revision of 2026-10-05
Machine-drafted from the cited Wikipedia passages and checked by a reviewing model, not by a human editor. Every passage cites the revision it was written from; dates and places follow those passages.