Wordorigins.org

Holmium, element 67, isn’t named for Ytterby, Sweden, but it comes close, geographically at least. The metal was discovered independently in 1878 by Swiss chemists Marc Delafontaine and Jacques-Louis Soret and by Swedish chemist and geologist Per Teodor Cleve. The latter describes how he came up with the name in the 12 September 1879 issue of Chemical News and Journal of Physical Science:

I propose for this metal the name of Holmium, Ho, derived from the latinized name of Stockholm, in the neighbourhood of which so many minerals rich in yttria are to be found.¹

Holmium has the chemical symbol Ho.

¹Oxford English Dictionary, holmium, 2nd Edition, 1989, Oxford University Press, accessed 22 October 2009, http://dictionary.oed.com/cgi/entry/50107243.

Dysprosium, element 66, was isolated in 1886 by French chemist Paul Émile Lecoq de Boisbaudran. Because of the difficulty he had in separating the element from the other substances in the sample, De Boisbaudran dubbed the new element after the Greek δυσπρόσιτος (dysprositos), meaning difficult to access.¹

Dysprosium has the chemical symbol Dy.

¹Oxford English Dictionary, dysprosium, 2nd Edition, 1989, Oxford University Press, accessed 21 October 2009, http://dictionary.oed.com/cgi/entry/50071430. 

Ytterby, Sweden is a small mining village that has, amazingly, bequeathed its name to four elements that were discovered in ores from the local mine; terbium, element 65, is one of these. The metal was discovered and named in 1843 by Swedish chemist Carl Gustaf Mosander. He writes in an 1843 issue of the London, Edinburgh, and Dublin Philosophical Magazine:

What chemists have hitherto considered as yttria, does not consist of one oxide only, but is [...] to be regarded as a mixture of at least three. [...] If the name of yttria be reserved for the strongest of these bases, and the next in order receive the name of oxide of terbium, while the weakest be called oxide of erbium, we find [etc.].¹

Terbium has the chemical symbol Tb.

The other elements named after Ytterby are yttrium, ytterbium, and erbium.

¹Oxford English Dictionary, terbium, 2nd Edition, 1989, Oxford University Press, accessed 20 October 2009, http://dictionary.oed.com/cgi/entry/50249249.

Gadolinium, element 64, was isolated in 1886 by Swiss chemist Jean Charles Galissard de Marignac. De Marignac found the element in a sample of the mineral gadolinite, hence its name.¹ Gadolinite, in turn, is named after Finnish chemist and geologist Johan Gadolin.²

Gadolinium has the chemical symbol Gd.

¹Oxford English Dictionary, gadolinium, 2nd Edition, 1989, Oxford University Press, accessed 19 October 2009, http://dictionary.oed.com/cgi/entry/50091509.

²Oxford English Dictionary, gadolinite, 2nd Edition, 1989, Oxford University Press, accessed 19 October 2009, http://dictionary.oed.com/cgi/entry/50091508. 

Europium, element 63, is, as one might expect, named after the continent of Europe. The element was first isolated in 1901 by French chemist Eugène-Anatole Demarçay who gave it its name.¹

Europium has the chemical symbol Eu.

¹Oxford English Dictionary, europium, 3rd Edition, March 2008, Oxford University Press, accessed 18 October 2009, http://dictionary.oed.com/cgi/entry/50078850. 

Languagehat has an excellent, if somewhat disturbing, example.

Mark Peters over at Good has an article on crash blossoms, confused readings of poorly worded/punctuated newspaper headlines. As in: “Violinist linked to JAL crash blossoms,” a story about a violinist whose career took off after his plane didn’t. Crash blossoms are like snowclones, eggcorns, mondegreens, and the Cupertino effect.

Samarium, element 62, is named after samarskite, the mineral from which it was first isolated. The mineral, in turn, takes its name from a 19th century Russian mining official, Vasily Samarsky-Bykhovets.¹

Samarium was isolated in 1879 by French chemist Paul Émile Lecoq de Boisbaudran who gave the element its name.²

Samarium has the chemical symbol Sm.

¹Oxford English Dictionary, samarskite, 2nd Edition, 1989, Oxford University Press, accessed 17 October 2009, http://dictionary.oed.com/cgi/entry/50212576.

²Oxford English Dictionary, samarium, 2nd Edition, 1989, Oxford University Press, accessed 17 October 2009, http://dictionary.oed.com/cgi/entry/50212571. 

Promethium, element 61, was discovered multiple times over the first half of the 20th century. The first was in 1924 by Italian scientists Luigi Rolla and Lorenzo Fernandes, who published their results in 1926. That year, Smith Hopkins and Len Yntema of the University of Illinois also announced discovery of the element. The American team dubbed the element illinium, after the university. From the 5 June 1926 issue of Nature:

X-ray analysis confirmed the theory and showed the presence of element number 61 in those fractions. [...] The name assigned to the element is Illinium (Il).¹

But neither discovery could be confirmed.

Then in 1945, Jacob A. Marinsky, Lawrence E. Glendenin and Charles D. Coryell at Oak Ridge National Laboratory finally managed to isolate the element and have the results duplicated. They dubbed their discovery promethium. Due to the war, publication of the discovery was delayed for several years, and on 30 June 1948, the Syracuse [NY] Herald-Journal had this:

The two chemists chose the name prometheum for Prometheus, the Titan in Greek mythology who stole fire from heaven for mankind’s use.²

Promethium has the chemical symbol Pm.

¹Oxford English Dictionary, illinium, 2nd Edition, 1989, Oxford University Press, accessed 16 October 2009, http://dictionary.oed.com/cgi/entry/50111959.

²Oxford English Dictionary, promethium, 3rd Edition, September 2009, Oxford University Press, accessed 16 October 2009, http://dictionary.oed.com/cgi/entry/50189861. 

See praseodymium.