The Collaborative International Dictionary
lanthanide \lanthanide\ n. Any rare earth element of the lanthanide series (atomic numbers 57 through 71).
Syn: rare earth, rare-earth element, lanthanon.
Wiktionary
n. (context chemistry English) Any of the 14 rare earth elements from cerium (or from lanthanum) to lutetium in the periodic table; because their outermost orbitals are empty, they have very similar chemistry; below them are the actinides.
WordNet
n. any element of the lanthanide series (atomic numbers 57 through 71) [syn: rare earth, rare-earth element, lanthanoid, lanthanon]
Wikipedia
The lanthanide or lanthanoid series of chemical elements comprises the fifteen metallic chemical elements with atomic numbers 57 through 71, from lanthanum through lutetium. These fifteen lanthanide elements, along with the chemically similar elements scandium and yttrium, are often collectively known as the rare earth elements.
The informal chemical symbol Ln is used in general discussions of lanthanide chemistry to refer to any lanthanide. All but one of the lanthanides are f-block elements, corresponding to the filling of the 4f electron shell; lutetium, a d-block element, is also generally considered to be a lanthanide due to its chemical similarities with the other fourteen. All lanthanide elements form trivalent cations, Ln, whose chemistry is largely determined by the ionic radius, which decreases steadily from lanthanum to lutetium.
They are termed lanthanides because the lighter elements in the series are chemically similar to lanthanum. Strictly speaking, both lanthanum and lutetium have been labeled as group 3 elements, because they both have a single valence electron in the d shell. However, both elements are often included in any general discussion of the chemistry of the lanthanide elements.
In presentations of the periodic table, the lanthanides and the actinides are customarily shown as two additional rows below the main body of the table, with placeholders or else a selected single element of each series (either lanthanum and actinium, or lutetium and lawrencium) shown in a single cell of the main table, between barium and hafnium, and radium and rutherfordium, respectively. This convention is entirely a matter of aesthetics and formatting practicality; a rarely used wide-formatted periodic table inserts the lanthanide and actinide series in their proper places, as parts of the table's sixth and seventh rows (periods).
Usage examples of "lanthanide".
When Giles said that all the Lanthanides were coming back to this reunion, I realized that there must be quite a lot of money in it somewhere.
The Lanthanides had never been prize physical specimens, but he supposed that their interest in science fiction may have stemmed in part from that.
After the first ceremonial spadeful of earth had been dug by each of the Lanthanides, accompanied by speeches in varying degrees of pomposity, Jim and Dale took turns digging the three-foot hole.
Conyers smiled at this bit of fancy, wondering if the other Lanthanides felt that way or if the reunion was a colorful way to make a buck.
The Lanthanides, as an organization, is but a golden memory in the minds of those of us who were a part of it, but its effect on SF springs eternal.
As all Trufandom knows, in the mid-Fifties, after the Lanthanides had gone their separate ways, the TVA turned the whole valley into a lake, and the famous Wall Hollow Fan Farm was hundreds of feet under water.
Sunday morning, followed by a press conference with the surviving Lanthanides and their newly acquired publisher, the high bidder of the auction.
He was the only one of the Lanthanides that she would really like to see, and he was dead.
It seemed to him that all the Lanthanides ever did was talk aimlessly and wait around for something to happen.
She was pleased to finally be in the know on a bit of Lanthanides gossip.
Except for the possibility of added prestige for a literary coup, which might result in money or perks, the Lanthanides Anthology Auction might as well be a Monopoly tournament.
Ashley, agent for Ruben Mistral and architect of the Lanthanides package, had hosted a prime-rib dinner for the group earlier in the evening, but she had wisely refrained from discussing business except to say that she for one felt privileged to be present at the making of a science fiction legend.
Usually, he dealt logically with problems that he could solve, and he wasted little time fretting over the rest, but the Lanthanides troubled him.
He explained his feelings about the other Lanthanides, and his own unwillingness to become like any of them in succeeding decades.
The more perceptive of the Lanthanides might assume that I was here to do more of the same.