Who created the periodic table?
Quick answer
Russian chemist Dmitri Mendeleev created the first widely accepted periodic table in 1869. He arranged the 63 known elements by atomic weight and grouped those with similar properties. Crucially, he left gaps for elements not yet discovered and predicted their properties, which were later found to be remarkably accurate.
Key facts
- Creator
- Dmitri Mendeleev (1834–1907)
- Year
- 1869
- Elements known then
- 63
- Elements today
- 118
The gaps that proved him right
| Mendeleev’s name | Discovered as | Year |
|---|---|---|
| Eka-aluminium | Gallium | 1875 |
| Eka-boron | Scandium | 1879 |
| Eka-silicon | Germanium | 1886 |
When these elements were found, their weights, densities and behaviors closely matched his predictions, convincing scientists that his table reflected a real pattern in nature.
The legend of the dream
Mendeleev reportedly said he saw the arrangement in a dream after days of work, writing the elements on cards and arranging them like a game of patience (solitaire). Historians debate how true the story is.
Others who came close
| Scientist | Contribution |
|---|---|
| Johann Döbereiner (1829) | Grouped elements in “triads” with similar properties |
| John Newlands (1865) | Noticed properties repeated every eighth element, his “law of octaves” |
| Lothar Meyer (1864–1870) | Built a similar table independently of Mendeleev |
Mendeleev got most of the credit because of his bold predictions.
How the modern table works
In 1913, British physicist Henry Moseley showed that elements should be ordered by atomic number, the number of protons, rather than weight. This fixed a few odd spots in Mendeleev’s table. See which element has atomic number 6.
| Feature | Meaning |
|---|---|
| Periods (rows) | Seven rows, each adding an electron shell |
| Groups (columns) | 18 columns of elements with similar chemistry |
| Metals | Left and center |
| Nonmetals | Upper right |
| Noble gases | Far right column |
Honors
Element 101 was named mendelevium in his honor in 1955. Today, the table has 118 confirmed elements; new names are approved by IUPAC; see who names chemical elements.
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