Discovery of the nonmetals

Carbon (C) and sulfur (S) were known in antiquity.

The earliest known use of charcoal dates to around 3750 BCE. The Egyptians and Sumerians employed it for the reduction of copper, zinc, and tin ores in the manufacture of bronze. Diamonds were probably known from as early as 2500 BCE. The first true chemical analyses were made in the 18th century; Antoine Lavoisier recognized carbon as an element in 1789.

Sulfur usage dates from before 2500 BCE; it was also recognized as an element by Lavoisier, in 1777.

Phosphorus (P) was prepared from urine, by Hennig Brand, in 1669.

Henry Cavendish, in 1766, was the first to distinguish hydrogen (H) from other gases, although Paracelsus around 1500, Robert Boyle (1670), and Joseph Priestley (?) had observed its production by reacting strong acids with metals. Lavoisier named it in 1793.

Carl Wilhelm Scheele obtained oxygen (O) by heating mercuric oxide (HgO) and nitrates in 1771, but did not publish his findings until 1777. Priestley also prepared this new "air" by 1774, but only Lavoisier recognized it as a true element; he named it in 1777.

Ernest Rutherford discovered nitrogen (N) while he was studying at the University of Edinburgh. He showed that the air in which animals breathed, after removal of exhaled carbon dioxide (CO₂), was no longer able to burn a candle. Scheele, Cavendish, and Priestley also studied this element at about the same time; Lavoisier named it in 1775 or 1776.

In 1774, Scheele obtained chlorine (Cl) from hydrochloric acid (HCl) but thought it was an oxide. Only in 1808 did Humphry Davy recognize it as an element.

Iodine (I) was discovered in 1811 by Bernard Courtois from the ashes of seaweed.

In 1817, when Jöns Jacob Berzelius and Johan Gottlieb Gahn were working with lead (Pb) they discovered a substance that was similar to tellurium (Te). After more investigation Berzelius concluded that it was a new element, related to sulfur and tellurium. Because tellurium had been named for the Earth, Berzelius named the new element "selenium" (Se), after the moon.

Antoine Jérôme Balard and Leopold Gmelin both discovered bromine (Br) in the autumn of 1825 and published their results in the following year.

In 1868, Pierre Janssen and Norman Lockyer independently observed a yellow line in the solar spectrum that did not match that of any other element. In 1895, in each case at around the same time, William Ramsay, Per Teodor Cleve, and Abraham Langlet independently observed helium (He) trapped in cleveite.

André-Marie Ampère predicted an element analogous to chlorine obtainable from hydrofluoric acid (HF), and between 1812 and 1886 many researchers tried to obtain it. Fluorine (F) was eventually isolated in 1886 by Henri Moissan.

Lord Rayleigh and Ramsay discovered argon (Ar) in 1894 by comparing the molecular weights of nitrogen prepared by liquefaction from air, and nitrogen prepared by chemical means. It was the first noble gas to be isolated. Lord Rayleigh would receive the Nobel Prize in Physics for "for his investigations of the densities of the most important gases and for his discovery of argon in connection with these studies".

In 1898, within a period of three weeks, Ramsay and Travers successively separated krypton (Kr), neon (Ne) and xenon (Xe) from liquid argon by exploiting differences in their boiling points.

In 1899, Rutherford and Robert B. Owens discovered a radioactive gas resulting from the radioactive decay of thorium (Th); Ramsay and Robert Whytlaw-Gray subsequently isolated radon (Rn) in 1910.