The credit for discovering oxygen is now shared by three chemists: an Englishman, a Swede, and a Frenchman. Joseph Priestley was the first to publish an account of oxygen, having made it in 1774 by focussing sunlight on to mercuric oxide (HgO), and collecting the gas which came off.

Nitrogen in the form of ammonium chloride, NH 4 Cl, was known to the alchemists as sal ammonia. It was manufactured in Egypt by heating a mixture of dung, salt and urine. Nitrogen gas itself was obtained in the 1760s by both Henry Cavendish and Joseph Priestley and they did this by removing the oxygen from air.

Element Hydrogen (H), Group 1, Atomic Number 1, s-block, Mass 1.008. Sources, facts, uses, scarcity (SRI), podcasts, alchemical symbols, videos and images.

Silicon makes up 27.7% of the Earth’s crust by mass and is the second most abundant element (oxygen is the first). It does not occur uncombined in nature but occurs chiefly as the oxide (silica) and as silicates.

The first lithium mineral petalite, LiAlSi 4 O 10, was discovered on the Swedish island of Utö by the Brazilian, Jozé Bonifácio de Andralda e Silva in the 1790s.It was observed to give an intense crimson flame when thrown onto a fire. In 1817, Johan August Arfvedson of Stockholm analysed it and deduced it contained a previously unknown metal, which he called lithium.

Hydrochloric acid (HCl) was known to the alchemists. The gaseous element itself was first produced in 1774 by Carl Wilhelm Scheele at Uppsala, Sweden, by heating hydrochloric acid with the mineral pyrolusite which is naturally occuring manganese dioxide, MnO 2.A dense, greenish-yellow gas was evolved which he recorded as having a choking smell and which dissolved in water to give an acid solution.

Lime (calcium oxide, CaO) was the useful material obtained by heating limestone and used for centuries to make plaster and mortar. Antoine Lavoisier classified it as an ‘earth’ because it seemed impossible to reduce it further, but he suspected it was the oxide of an unknown element.

Potassium salts in the form of saltpetre (potassium nitrate, KNO 3), alum (potassium aluminium sulfate, KAl(SO 4) 2), and potash (potassium carbonate, K 2 CO 3) have been known for centuries.They were used in gunpowder, dyeing, and soap making. They were scraped from the walls of latrines, manufactured from clay and sulfuric acid, …

Interactive periodic table with information on element scarcity, discovery dates, melting and boiling points, group, block, and period.

In 1898, William Ramsay and Morris Travers at University College London isolated krypton gas by evaporating liquid argon. They had been expecting to find a lighter gas which would fit a niche above argon in the periodic table of the elements.