Portion of the periodic table containing holmium (Ho) and thulium (Tm)
20 October 2023
Holmium, atomic number 67 and symbol Ho, and thulium, atomic number 69 and symbol Tm, are soft, malleable, silvery metals. Their oxides were first isolated by Per Teodor Cleve in 1879, although the existence of holmium had been observed spectrographically the previous year by Jacques-Louis Soret and Marc Delafontaine. Holmium is used in the production of lasers and spectrometers, as well as magnets, and it is used as a neutron regulator in nuclear reactors. Thulium is used in some portable x-ray devices and in lasers, but its rarity and resulting high price limit its practical utility.
Cleve proposed the names for both elements. Holmium is named for Stockholm, whose modern Latin name is Holmia. Thulium is named for Thule, a classical Latin name for a specific but vaguely identified land in the North Sea region. In the announcement of his discovery, published 1 September 1879, Cleve wrote of the names:
Pour le radical de l’oxyde placé entre l’ytterbine et l’erbine, qui est caractérisé par la band x dans la partie rouge du spectre, je propose le nom de thulium, dérivé de Thulé, le plus ancient nom de la Scandinavie.
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Le troisième metal, caractérisé par les bandes y et z et qui se trouve entre l’erbine et la terbine, doit avoir un poids atomique inférieur à 108. Son oxyde paraît être jaune; au moins toutes les fractions d’un poids moléculaire inférieur à 126 sont plus ou moins jaunes. Je propose pour le metal le nom de holmium, Ho, dérivé du nom latinsé de Stockholm, don’t les environs renferment tant de minéraux riches en yttria.
(For the radical of the oxide placed between ytterbia and erbia, which is characterized by the band x in the red part of the spectrum, I propose the name of thulium, derived from Thule, the ancient name of Scandinavia.
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The third metal characterized by the bands y and z, and which is found between erbia and terbia, must have a lower atomic number than 108. Its oxide appears to be yellow; at least all the fractions of the molecular weight lower than 108 are more or less yellow. I propose for this metal the name Holmium, Ho, derived from the latinized name of Stockholm, in the neighborhood of which so many minerals rich in yttria are to be found.)
Sources:
Clève, P. T. “On Two New Elements in Erbia.” Chemical News, 40.1033, 12 September 1879, 125–126 at 126. HathiTrust Digital Library.
———. “Sur deux nouveaux éléments dans l’ erbine.” Comptes rendus hebdomadaires des séances de l'Académie des sciences, 89.9, 1 September 1879, 478–80 at 480. Biodiversity Heritage Library.
Miśkowiec, Pawel. “Name Game: The Naming History of the Chemical Elements: Part 2—Turbulent Nineteenth Century." Foundations of Chemistry, 8 December 2022. DOI: 10.1007/s10698-022-09451-w.
Oxford English Dictionary, second edition, 1989, s.v. holmium, n., thulium, n.
Image credit: N. Hanacek, 2019, National Institute of Standards and Technology (NIST). Public domain image.