Editing Chemical element (section)

==== Antoine Lavoisier, Jöns Jacob Berzelius, and Dmitri Mendeleev ====
[[File:Mendeleev's 1869 periodic table.svg|upright=1.35|thumb|[[Mendeleev]]'s 1869 periodic table: ''An experiment on a system of elements. Based on their atomic weights and chemical similarities.'']]The first modern list of elements was given in [[Antoine Lavoisier]]'s 1789 ''[[Traité Élémentaire de Chimie|Elements of Chemistry]]'', which contained 33 elements, including [[light]] and [[Caloric theory|caloric]].<ref>{{cite book|last=Lavoisier|first=A. L.|year=1790|title=Elements of chemistry translated by Robert Kerr|url=https://books.google.com/books?id=4BzAjCpEK4gC&pg=PA175|place=Edinburgh|pages=175–176|isbn=978-0-415-17914-0|access-date=24 August 2020|archive-date=14 April 2021|archive-url=https://web.archive.org/web/20210414100525/https://books.google.com/books?id=4BzAjCpEK4gC&pg=PA175|url-status=live}}</ref><ref>{{Cite book |last=Lavoisier |first=Antoine |author-link=Antoine Lavoisier |url=https://www.gutenberg.org/cache/epub/30775/pg30775-images.html#Page_175 |title=Elements of chemistry: In a new systematic order, containing all the modern discoveries: Illustrated with thirteen copperplates |publisher=William Creech |year=1790 |pages=175–176 |language=en |translator-last=Kerr |translator-first=Robert |orig-date=1789}}</ref> By 1818, [[Jöns Jacob Berzelius]] had determined atomic weights for 45 of the 49 then-accepted elements. [[Dmitri Mendeleev]] had 63 elements in his 1869 periodic table.
[[File:DIMendeleevCab.jpg|thumb|left|upright|Dmitri Mendeleev, 1897]]
From Boyle until the early 20th century, an element was defined as a pure substance that cannot be decomposed into any simpler substance and cannot be transformed into other elements by chemical processes. Elements at the time were generally distinguished by their atomic weights, a property measurable with fair accuracy by available analytical techniques.