Crossword clues for actinium
The Collaborative International Dictionary
Actinium \Ac*tin"i*um\, n. [Gr. ?, ?, ray.] (Chem.) A supposed metal, said by Phipson to be contained in commercial zinc; -- so called because certain of its compounds are darkened by exposure to light.
Douglas Harper's Etymology Dictionary
radioactive element discovered in 1899, from Greek actin-, comb. form of aktis (genitive aktinos) "ray, radiance" (see actino-) + chemical suffix -ium.
Wiktionary
n. a radioactive, metallic chemical element (''symbol'': Ac) with an atomic number of 89; found in uranium ores
WordNet
n. a radioactive element of the actinide series; found in uranium ores [syn: Ac, atomic number 89]
Wikipedia
Actinium is a radioactive chemical element with symbol Ac (not to be confused with the abbreviation for an acetyl group) and atomic number 89, which was discovered in 1899. It was the first non-primordial radioactive element to be isolated. Polonium, radium and radon were observed before actinium, but they were not isolated until 1902. Actinium gave the name to the actinide series, a group of 15 similar elements between actinium and lawrencium in the periodic table. It is also sometimes considered the first of the 7th-period transition metals.
A soft, silvery-white radioactive metal, actinium reacts rapidly with oxygen and moisture in air forming a white coating of actinium oxide that prevents further oxidation. As with most lanthanides and many actinides, actinium assumes oxidation state +3 in nearly all its chemical compounds. Actinium is found only in traces in uranium and thorium ores as the isotope Ac, which decays with a half-life of 21.772 years, predominantly emitting beta and sometimes alpha particles, and Ac, which is beta active with a half-life of 6.15 hours. One tonne of natural uranium in ore contains about 0.2 milligrams of actinium-227, and one tonne of natural thorium contains about 5 nanograms of actinium-228. The close similarity of physical and chemical properties of actinium and lanthanum makes separation of actinium from the ore impractical. Instead, the element is prepared, in milligram amounts, by the neutron irradiation of in a nuclear reactor. Owing to its scarcity, high price and radioactivity, actinium has no significant industrial use. Its current applications include a neutron source and an agent for radiation therapy targeting cancer cells in the body.
Usage examples of "actinium".
The Sherlock and the Watson floated alongside the offloaded actinium waiting for a lighter to arrive and recover the stolen merchandise.
If you consider an alphabetical listing of the elements, actinium, element number eighty-nine, is first on the list, and zirconium, element number forty, is the last on the list.
It was a compound of actinium, a substance far more radioactive than radium, but of lesser duration.
THE SHADOW folded the actinium powder in a small piece of paper that he found in the wastebasket.
By that time, his actinium powder would be as traceless as it had been with Rune.
He had developed actinium compounds that could kill - as demonstrated in the cases of Rune and Farradon.
The Sherlock and the Watson floated alongside the offloaded actinium waiting for a lighter to arrive and recover the stolen merchandise.
The intermediate elements referred to in this radioactive decay chain are lead (symbol Pb, element 82), polonium (Po, element 84), astatine (At, element 85), francium (Fr, element 87), radium (Ra, element 88), actinium (Ac, element 89), thorium (Th, element 90), protoactinium (Pa, element 91), uranium (U, element 92), neptunium (Np, element 93), and americium (Am, element 95).