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The discoveries of the 118 chemical elements known to exist as of 2025 are presented here in chronological order. The elements are listed generally in the order in which each was first defined as the pure element, as the exact date of discovery of most elements cannot be accurately determined.
This is an accepted version of this page This is the latest accepted revision, reviewed on 28 January 2025. Development of the table of chemical elements The American chemist Glenn T. Seaborg —after whom the element seaborgium is named—standing in front of a periodic table, May 19, 1950 Part of a series on the Periodic table Periodic table forms 18-column 32-column Alternative and extended ...
Prout's hypothesis was an early 19th-century attempt to explain the existence of the various chemical elements through a hypothesis regarding the internal structure of the atom. In 1815 [ 1 ] and 1816, [ 2 ] the English chemist William Prout published two papers in which he observed that the atomic weights that had been measured for the ...
Initiated the theory of valency by proposing that each element has a specific "combining power", e.g. some elements such as nitrogen tend to combine with three other elements (e.g. NO 3) while others may tend to combine with five (e.g. PO 5), and that each element strives to fulfill its combining power (valency) quota. 1857: Heinrich Geissler
Following Jeremias Benjamin Richter (known for introducing the term stoichiometry), he proposed that chemical elements combine in integral ratios. This is known as the law of multiple proportions or Dalton's law, and Dalton included a clear description of the law in his New System of Chemical Philosophy. The law of multiple proportions is one ...
An image from John Dalton's A New System of Chemical Philosophy, the first modern explanation of atomic theory.. This timeline of chemistry lists important works, discoveries, ideas, inventions, and experiments that significantly changed humanity's understanding of the modern science known as chemistry, defined as the scientific study of the composition of matter and of its interactions.
The mineral columbite The element niobium. In 1846, Rose rediscovered the chemical element niobium, proving conclusively that it was different from tantalum. This confirmed that Charles Hatchett had discovered niobium in 1801 in columbite ore. Hatchett had named the new element "columbium", from the ore in which niobium and tantalum coexist.
Pages in category "Discoverers of chemical elements" The following 101 pages are in this category, out of 101 total. This list may not reflect recent changes .