Chlorine 36 age dating
First reference to it as a new metal was made by William Brownrigg in 1750.
Obtained it by heating mercuric oxide and nitrates in 1771, but did not publish his findings until 1777.
In 1900, Friedrich Ernst Dorn discovered a longer-lived isotope of the same gas from the radioactive decay of radium.
Since "radon" was first used to specifically designate Dorn's isotope before it became the name for the element, he is often mistakenly given credit for the latter instead of the former.
André-Louis Debierne had previously reported the discovery of a new element actinium that was supposedly similar to titanium and thorium; the elements were mistakenly identified as being identical and Debierne's name was chosen, even though in retrospect Debierne's substance could not have included much actual element 89Welsbach proved that the old ytterbium also contained a new element, which he named cassiopeium.
Urbain also proved this simultaneously, but his samples were very impure and only contained trace quantities of the new element.
The discovery of the 118 chemical elements known to exist today is 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 defined. Given is each element's name, atomic number, year of first report, name of the discoverer, and some notes related to the discovery.
Ulloa published his findings in 1748, but Sir Charles Wood also investigated the metal in 1741.The discovery of smelting around 3000 BCE led to the start of the iron age around 1200 BCEFirst smelted in combination with copper around 3500 BCE to produce bronze (and thus giving place to the Bronze Age in those places where Iron Age didn't intrude directly on Neolithic of the Stone Age).Extracted as a metal since antiquity (before 1000 BCE) by Indian metallurgists, but the true nature of this metal was not understood in ancient times.Gregor found an oxide of a new metal in ilmenite; Martin Heinrich Klaproth independently discovered the element in rutile in 1795 and named it.The pure metallic form was only obtained in 1910 by Matthew A. Río found the metal in vanadinite but retracted the claim after Hippolyte Victor Collet-Descotils disputed it.