Swedish chemist and surgeon · 1797–1858
Carl Gustaf Mosander
Carl Gustaf Mosander showed that the rare earths were not single substances but mixtures. By patiently splitting them apart he found lanthanum, erbium and terbium, and set off a century-long hunt for the rest.
- Elements credited
- 3
- Discoveries
- 1839–1843
- Co-discoverers
- 0
- Where
- Sweden
Discovery timeline
1839 · Sweden
Lanthanum is a soft, silvery rare-earth metal that gives its name to the lanthanide series.
1843 · Sweden
Terbium is a soft, silvery rare-earth metal. It produces bright green light in screens and low-energy lamps.
1843 · Sweden
Erbium is a silvery rare-earth metal. Erbium-doped fibre amplifiers carry the internet across oceans.
The discoveries
Ceria had been known since 1803. In 1839 Mosander heated cerium nitrate and treated it with dilute nitric acid, which left part of the material undissolved. The soluble part contained a new element he called lanthanum, from the Greek for “to lie hidden”. He also separated a substance he called didymium, “twin”, which later proved to be two elements.
In 1843 he applied the same idea to yttria and split it into three fractions: yttria itself and two new earths he named erbia and terbia, after the village of Ytterby. The names of the two were later swapped by other chemists, so his “erbium” is today’s terbium and the other way round.
Life and career
Mosander was born in Kalmar and trained as a pharmacist and army surgeon. He became Berzelius’s assistant and eventually succeeded him as professor of chemistry and pharmacy at the Karolinska Institute in Stockholm.
He also served as curator of minerals at the Swedish Museum of Natural History.
Also known for
- Discovered didymium, later split into praseodymium and neodymium
- Showed that rare-earth “earths” were mixtures