Crossword clues for actinide
Wiktionary
n. (context inorganic chemistry English) Any of the 14 radioactive elements of the periodic table that are positioned under the lanthanides to which they have similar chemistry.
WordNet
Wikipedia
The actinide or actinoid ( IUPAC nomenclature) series encompasses the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium.
The actinide series derives its name from the first element in the series, actinium. The informal chemical symbol An is used in general discussions of actinide chemistry to refer to any actinide. All but one of the actinides are f-block elements, corresponding to the filling of the 5f electron shell; lawrencium, a d-block element, is also generally considered an actinide. In comparison with the lanthanides, also mostly f-block elements, the actinides show much more variable valence. They all have very large atomic and ionic radii and exhibit an unusually large range of physical properties. While actinium and the late actinides (from americium onwards) behave similarly to the lanthanides, the elements thorium through neptunium are much more similar to transition metals in their chemistry.
All actinides are radioactive and release energy upon radioactive decay; naturally occurring uranium and thorium, and synthetically produced plutonium are the most abundant actinides on Earth. These are used in nuclear reactors and nuclear weapons. Uranium and thorium also have diverse current or historical uses, and americium is used in the ionization chambers of most modern smoke detectors.
Of the actinides, primordial thorium and uranium occur naturally in substantial quantities and small amounts of persisting natural plutonium have also been identified. The radioactive decay of uranium produces transient amounts of actinium and protactinium, and atoms of neptunium and plutonium are occasionally produced from transmutation reactions in uranium ores. The other actinides are purely synthetic elements. Nuclear weapons tests have released at least six actinides heavier than plutonium into the environment; analysis of debris from a 1952 hydrogen bomb explosion showed the presence of americium, curium, berkelium, californium, einsteinium and fermium.
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 or lutetium, and either actinium or lawrencium, respectively) 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 "actinide".
Stalinist lapels and hemlines into spangly kitsch, the Day-Glo designer industrial-waste outlets vending pet elements from beyond the actinide seriesin all this synthetic needs-mongering, Kraft and Linda stumble upon a bookstore.
This was Touch-Down Time, when the citizens of the bustling, prosperous planet of Fomalhaut V - rich in the transuranics, the actinides, so vital as the energy fuels needed to extend the surge of colonization to every habitable planet in the spiral of the Milky Way - relaxed industry and inhibitions in a three-day spectacular of day-long contests, night-long dancing, and eating and carousing.
And Ireta, a satellite of a suspected third generation sun, ought to be rich in the heavier elements, rich in the transuranics and actinides, neptunium, plutonium and the more esoteric of the rare elements above uranium on the periodic table, so urgently and constantly required by the Federation of Sentient Populations, the search for which was one of the primary tasks of the EEC.
But there's also three more rows of lights underneath where the actinide series usually goes.