The first person to recognise that magnesium was an element was Joseph Black at Edinburgh in 1755. He distinguished magnesia (magnesium oxide, MgO) from lime (calcium oxide, CaO) although both were produced by heating similar kinds of carbonate rocks, magnesite and limestone respectively.

Radium was discovered in 1898 by Marie Curie and Pierre Curie. They managed to extract 1 mg of radium from ten tonnes of the uranium ore pitchblende (uranium oxide, U 3 O 8), a considerable feat, given the chemically methods of separation available to them.They identified that it was a new element because its atomic spectrum revealed new lines.

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.

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.

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

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

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.

The art of alchemy was handed down through the centuries from Egypt and Arabia to Greece and Rome, and finally to western and central Europe. The word is derived from the Arabian phrase "al-kimia," which refers to the preparation of the Stone or Elixir by the Egyptians.

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 …

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.