October 2, 1852, in Glasgow (Scotland) – July 23, 1916, Buckinghamshire (United Kingdom)
He studied chemistry at the University of Glasgow, graduating in 1870, and received his doctorate from the University of Tübingen, Germany, in 1872, with a thesis on o-toluic acid.
That same year he returned to Scotland to work at Anderson College until he was hired at the University of Glasgow (1874-1880). During these four years, he investigated alkaloids (a nitrogenous substance found in certain vegetables and constitutes a natural stimulant; it can be poisonous and is sometimes used in medical therapies).
In 1880, he became a professor at University College, Briston, where he was director from 1881 to 1887. He carried out research on the physical characteristics of liquids and gases together with another chemist, Sydney Young, with whom he published more than 30 articles.
In 1887, he obtained a position as Professor of General Chemistry at University College London, where he remained until his retirement in 1913.
In 1892, John William Strutt, better known as Lord Rayleigh, discovered a difference in the data on nitrogen gas in compounds and in the atmosphere that he attributed to a light gas included in chemical compounds of nitrogen, whereas Ramsay suspected that it was of a hitherto unknown heavy gas.
After using two different methods to remove all known gases from the air, the two were able to announce in 1894 that they had found a chemically inert, monatomic gaseous element that made up almost 1% of the atmosphere. They named it after the Greek word for "lazy," argon.
In 1893, together with John Shields, he verified the physical law established by Roland Eötvös on the constancy of the rate of change of molecular surface energy with temperature.
That same year, Ramsay released another inert gas from a mineral called cleveite, which turned out to be helium.
In 1896, he published "The Gases of the Atmosphere" in which he indicated that due to the positions of helium and argon in the periodic table there could be at least three more noble gases.
In 1898, working with Morris W. Travers, he isolated the elements neon, krypton, and xenon from air, and in 1903, working with Frederick Soddy, he showed that helium (along with a gaseous emanation called radon) is continually produced during radioactive decay of radium. It was a discovery of great importance for the understanding of nuclear reactions.
In 1910, using small samples of radon, he showed that it is a sixth noble gas and provided further evidence that it was formed by emission from a helium nucleus and from radium.
He supported science education and was the first to write two textbooks in 1891 based on the periodic classification of the elements: "A System of Inorganic Chemistry" and "Elementary Systematic Chemistry for Use in Colleges and Universities."
He was appointed Sir in 1902 and two years later he received the Nobel Prize in Chemistry for the discovery of the components of air and determining their position in the periodic table of elements. Interestingly, his collaborator and friend John William Strutt received the Nobel Prize in Physics that same year.