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The electronic configuration of the atom. Actinium




actinium, German Actinium) - Radioactive chemical element of group III of the periodic system of elements, symbol Ac, at. n. 89; at.m. 227.0278. The beta radioactive isotope 227 Ac lives longer. The half-life is 21.773 g. The isotopes 227 As and 228 As (also called mesothorium II, Ms Th II) are part of the natural radioactive series. The content of actinium in the earth's crust is very small (). Actinium is a silvery-white metal with a granocentric cubic lattice.

Quite heavy (density 10.7 g/cm3) and very chemically active. Its melting point, determined experimentally, is 1040? fifty ? C, and the boiling point, calculated theoretically, is about 3200? FROM

Found in uranium and thorium ores. Highly toxic. t pl \u003d 1050 o C, t kip \u003d 3590 o C.


1.1. Chemical properties

Configuration of outer electron shells 6d7s2; the energy of successive ionization, respectively, is 6.9; 12.06, 20 eV. Metallic radius 0.203 nm, ion radius (+3) 0.111 nm. The electronegativity value is 1.00. Similar in chemical properties to lanthanum. They have very similar chemical properties: common valency (3 +), close atomic radii (1.87 and 2.03 A), the structure of most compounds is almost identical. In air, actinium is oxidized to Ac 2 O 3. As in lanthanum, most actinium salts are white; oxide also. And the fact that actinium surpasses lanthanum in chemical activity is quite natural. This is a heavy metal analog: valence electrons circulate farther from the nucleus. Glows in the dark due to high radioactivity.


2. History


5. Application

The practical use of actinium is limited to neutron sources. Neutrons in them are formed when beryllium-9 is irradiated with alpha particles. And the daughter products of actinium-227 give alpha particles. There are reasons to believe that actinium-beryllium neutron sources are by no means the best and not the most economical of devices for this purpose.

    - (Greek). The radioactive element, the companion of zinc, is somewhat like thorium. Dictionary of foreign words included in the Russian language. Chudinov A.N., 1910. ACTINIUS sea anemones, sea. nettle or lily animals from class. polyps, bright colors. ... ... Dictionary of foreign words of the Russian language

    - (Ac) radioactive chem. element III gr. periodic system, serial number 89, the mass number of the longest-lived isotope is 227. Its prevalence in the earth's crust is 6 10 10% by weight. Ac227 is a member of the radioactive actinouranium (U235) ... ... Geological Encyclopedia

    - (Actinium), Ac, a radioactive chemical element of group III of the periodic system, atomic number 89; metal. Actinium was discovered in 1899 by the French chemist A. Debierne ... Modern Encyclopedia

    Actinium- (Actinium), Ac, a radioactive chemical element of group III of the periodic system, atomic number 89; metal. Actinium was discovered in 1899 by the French chemist A. Debierne. … Illustrated Encyclopedic Dictionary

    - (lat. Actinium) Ac, a chemical element of group III of the periodic system, atomic number 89, atomic mass 227.0278. Radioactive, the most stable isotope is 227Ac (half-life 21.8 years). The name is from the Greek aktis ray. Silvery white… … Big Encyclopedic Dictionary

    - (from the Greek aktis, genus case aktinos ray, sparkle, radiance; Pat. Actinium), Ac, radio act. chem. group III element periodic. systems of elements, at. number 89, the first of the elements of the actinide family. Naib. long-lived radioactive isotope 227 As ... ... Physical Encyclopedia

    Exist., number of synonyms: 3 actinoid (16) actinouranium (1) element (159) Dictionary with ... Synonym dictionary

    Opened by the Englishman Finson (1881) A new element, a companion of zinc; its chemical individuality, however, cannot be considered established. F. noticed that in some cases the white precipitate of zinc sulfide darkens in direct sunlight ... ... Encyclopedia of Brockhaus and Efron

    ACTINIUM- (from the Greek aktis beam), a radioactive chemical element (at. v. 226). Its ancestor, apparently, is uranium, and actinium lead is the final decay product. The activity of A. decreases by half in 20 years. Lit .: Faience K., ... ... Big Medical Encyclopedia

    actinium- Radioact. element III gr. Periodic systems; at. n. 89. Discovered in 1899 by A. Debierne in the remains of uranium ores after the extraction of uranium. The longest-lived isotope of the 12 known 227Ac (T1 / 2 \u003d 21.7 g, P ... Technical Translator's Handbook

Books

  • Illustrated keys to free-living invertebrates of the Eurasian seas and adjacent deep-water parts of the Arctic. Volume 3, Sirenko B.I. The third volume of the guides includes scyphoid jellyfish, stauromedusa, siphonophores, hydroid polyps and jellyfish, sea anemones, antipataria, soft corals, ceriantharia. sea ​​feathers, madrepore ...
  • Illustrated keys to free-living invertebrates of the Eurasian seas and adjacent deep-water parts of the Arctic. Volume 3. Cnidaria and ctenophores,. The third volume of the guides includes scyphoid jellyfish, stauromedusa, siphonophores, hydroid polyps and jellyfish, sea anemones, antipatharia, soft corals, and ceriantharia. sea ​​feathers, madrepore ...

Actinium

ACTINIUM-I; m.[Greek aktis (aktinos) - ray]. Chemical element (Ac), a silver-white radioactive metal (found in uranium and thorium ores).

◁ Actinium, th, th.

actinium

(lat. Actinium), a chemical element of group III of the periodic system. Radioactive, the most stable isotope is 227 As (half-life 21.8 years). Name from Greek. actis - ray. Silver white metal t pl about 1050ºC. Occurs naturally in uranium and thorium ores. A mixture of 227 Ac and 9 Be is the source of neutrons.

ACTINIUM

ACTINIUM (lat. Actinium, from the Greek “actis” - a beam), Ac (read “actinium”), a radioactive chemical element with atomic number 89, the mass number of the most stable radionuclide actinium is 227 (half-life is 227 As T 1/2 21.8 years). Located in IIIB group, 7th period of the Periodic Table of Elements.
Electronic configuration of two outer layers of an unexcited actinium atom 6 s 2 p 6 d 1 7s 2; oxidation state +3 (valency III). Electronegativity according to Pauling (cm. PAULING Linus) 1,1.
Discovery history
Discovered in 1899 by the French explorer A. Debierne (cm. DEBIERNE Andre) in the waste processing of uranium ore and, independently of him, in 1908 - F. Gisel.
Being in nature
The content in the earth's crust is about 6·10 -10% by weight. The constant presence of 227 Ac and less stable actinium 228 Ac in the earth's crust is associated with their inclusion in the radioactive series (cm. RADIOACTIVE SERIES) uranium-235 and thorium-232. The rate of formation of these radionuclides is equal to the rate of their radioactive decay, so the earth's crust contains constant quantities of these atoms.
Physical and chemical properties
Little studied. Melting point 1050 °C, boiling point 3300 °C. In air, it quickly becomes covered with an oxide film of Ac 2 O 3, which prevents the destruction of the metal.
Actinium is chemically similar to lanthanum. (cm. LANTHANUM). Actinium hydroxide Ac(OH) 3 is a base and is close in properties to alkaline earth hydroxides.
Application
mixed with beryllium (cm. BERYLLIUM) 227 Ac is used to manufacture ampoule neutron sources produced by irradiating 9 Be nuclei with a particles emitted by 227 Ac. Actinium and its compounds are toxic, MPC 227 Ac 1.310 -6.


encyclopedic Dictionary. 2009 .

Synonyms:

See what "actinium" is in other dictionaries:

    - (Greek). The radioactive element, the companion of zinc, is somewhat like thorium. Dictionary of foreign words included in the Russian language. Chudinov A.N., 1910. ACTINIUS sea anemones, sea. nettle or lily animals from class. polyps, bright colors. ... ... Dictionary of foreign words of the Russian language

    - (Ac) radioactive chem. element III gr. periodic system, serial number 89, the mass number of the longest-lived isotope is 227. Its prevalence in the earth's crust is 6 10 10% by weight. Ac227 is a member of the radioactive actinouranium (U235) ... ... Geological Encyclopedia

    - (Actinium), Ac, a radioactive chemical element of group III of the periodic system, atomic number 89; metal. Actinium was discovered in 1899 by the French chemist A. Debierne ... Modern Encyclopedia

    Actinium- (Actinium), Ac, a radioactive chemical element of group III of the periodic system, atomic number 89; metal. Actinium was discovered in 1899 by the French chemist A. Debierne. … Illustrated Encyclopedic Dictionary

    - (lat. Actinium) Ac, a chemical element of group III of the periodic system, atomic number 89, atomic mass 227.0278. Radioactive, the most stable isotope is 227Ac (half-life 21.8 years). The name is from the Greek aktis ray. Silvery white… … Big Encyclopedic Dictionary

    - (from the Greek aktis, genus case aktinos ray, sparkle, radiance; Pat. Actinium), Ac, radio act. chem. group III element periodic. systems of elements, at. number 89, the first of the elements of the actinide family. Naib. long-lived radioactive isotope 227 As ... ... Physical Encyclopedia

    Exist., number of synonyms: 3 actinoid (16) actinouranium (1) element (159) Dictionary with ... Synonym dictionary

    Opened by the Englishman Finson (1881) A new element, a companion of zinc; its chemical individuality, however, cannot be considered established. F. noticed that in some cases the white precipitate of zinc sulfide darkens in direct sunlight ... ... Encyclopedia of Brockhaus and Efron

    ACTINIUM- (from the Greek aktis beam), a radioactive chemical element (at. v. 226). Its ancestor, apparently, is uranium, and actinium lead is the final decay product. The activity of A. decreases by half in 20 years. Lit .: Faience K., ... ... Big Medical Encyclopedia

    actinium- Radioact. element III gr. Periodic systems; at. n. 89. Discovered in 1899 by A. Debierne in the remains of uranium ores after the extraction of uranium. The longest-lived isotope of the 12 known 227Ac (T1 / 2 \u003d 21.7 g, P ... Technical Translator's Handbook

    89 Radium ← Actinium → Thorium ... Wikipedia

Books

  • Illustrated keys to free-living invertebrates of the Eurasian seas and adjacent deep-water parts of the Arctic. Volume 3, Sirenko B.I. The third volume of the guides includes scyphoid jellyfish, stauromedusa, siphonophores, hydroid polyps and jellyfish, sea anemones, antipataria, soft corals, ceriantharia. sea ​​feathers, madrepore ...
  • Illustrated keys to free-living invertebrates of the Eurasian seas and adjacent deep-water parts of the Arctic. Volume 3. Cnidaria and ctenophores,. The third volume of the guides includes scyphoid jellyfish, stauromedusa, siphonophores, hydroid polyps and jellyfish, sea anemones, antipatharia, soft corals, and ceriantharia. sea ​​feathers, madrepore ...