History of the periodic table
The periodic table did not emerge in its present form all at once. It developed through the work of scientists seeking relationships between elements. As new elements were discovered and their properties measured, recurring patterns helped bring similar elements into families.
From early classifications based on chemical properties and atomic weights, the table evolved into an arrangement by atomic number. Along the way, it became more than a list: it helped scientists predict missing elements and connect discoveries. The milestones below trace this shared scientific journey.
- 1789
Lavoisier: a starting list
Antoine Lavoisier listed 33 substances he considered elements. Some, including light and heat, are not elements by today’s definition.
Source: Royal Society of Chemistry ↗ - 1829
Döbereiner: families of three
Johann Döbereiner grouped chemically similar elements into triads. Their atomic weights suggested relationships that helped chemists look for broader patterns.
Source: Royal Society of Chemistry ↗ - 1864–1865
Meyer and Newlands: recurring patterns
Lothar Meyer developed tables linking element properties. John Newlands proposed the law of octaves: similarities returned at regular intervals, although the pattern had limitations.
Source: Royal Society of Chemistry ↗ - 1869
Mendeleev: leaving room for discovery
Dmitri Mendeleev organised elements using atomic weights and chemical similarities. He left gaps and predicted properties of missing elements, making the table a tool for discovery.
Source: Royal Society of Chemistry ↗ - 1913
Moseley: the atomic number
Henry Moseley’s X-ray measurements supported ordering elements by atomic number. This explained exceptions to ordering by atomic weight and established the basis of the modern sequence.
Source: Royal Society of Chemistry ↗ - 1944
Seaborg: the actinide series
Glenn Seaborg proposed the actinide concept, explaining how heavy elements form a series analogous to the lanthanides. It changed the placement of these elements in the table.
Source: Berkeley Lab ↗ - 2016
Four names complete the seventh period
On 28 November, IUPAC approved nihonium, moscovium, tennessine and oganesson as the names for elements 113, 115, 117 and 118. All elements of the seventh period now had approved names.
Source: IUPAC ↗
READING THE TABLE TODAY
Order by protons. Discover patterns.
The modern table increases by atomic number, the proton count. This timeline highlights selected contributions rather than every discovery.
Explore the periodic table ↗