Actinium compounds

Last updated May 13, 2024

Actinium compounds are compounds containing the element actinium (Ac). Due to actinium's intense radioactivity, only a limited number of actinium compounds are known. These include: AcF₃, AcCl₃, AcBr₃, AcOF, AcOCl, AcOBr, Ac₂S₃, Ac₂O₃, AcPO₄ and Ac(NO₃)₃. Except for AcPO₄, they are all similar to the corresponding lanthanum compounds. They all contain actinium in the oxidation state +3.^[1]^[2] In particular, the lattice constants of the analogous lanthanum and actinium compounds differ by only a few percent.^[2]

Properties of actinium compounds

Formula	color	symmetry	space group	No	Pearson symbol	a (pm)	b (pm)	c (pm)	Z	density, g/cm³
Ac	silvery	fcc ^[3]	Fm3m	225	cF4	531.1	531.1	531.1	4	10.07
AcH₂	unknown	cubic^[3]	Fm3m	225	cF12	567	567	567	4	8.35
Ac₂O₃	white^[4]	trigonal ^[5]	P3m1	164	hP5	408	408	630	1	9.18
Ac₂S₃	black	cubic^[6]	I43d	220	cI28	778.56	778.56	778.56	4	6.71
AcF₃	white^[7]	hexagonal ^[2]^[5]	P3c1	165	hP24	741	741	755	6	7.88
AcCl₃	white	hexagonal^[2]^[8]	P6₃/m	165	hP8	764	764	456	2	4.8
AcBr₃	white^[2]	hexagonal^[8]	P6₃/m	165	hP8	764	764	456	2	5.85
AcOF	white^[9]	cubic^[2]	Fm3m			593.1				8.28
AcOCl	white	tetragonal ^[2]				424	424	707		7.23
AcOBr	white	tetragonal^[2]				427	427	740		7.89
AcPO₄·0.5H₂O	unknown	hexagonal^[2]				721	721	664		5.48

Here a, b and c are lattice constants, No is space group number and Z is the number of formula units per unit cell. Density was not measured directly but calculated from the lattice parameters.

Oxides

Actinium(III) oxide is the only oxide that actinium can form, with the chemical formula Ac₂O₃. In this compound, actinium is in the oxidation state +3.^[1]^[10] It is similar to the corresponding lanthanum compound, lanthanum(III) oxide. It can be obtained by heating the hydroxide at 500 °C or the oxalate at 1100 °C, in vacuum. Its crystal lattice is isotypic with the oxides of most trivalent rare-earth metals.^[2]

Halides

Actinium trifluoride can be produced either in solution or in solid reaction. The former reaction is carried out at room temperature, by adding hydrofluoric acid to a solution containing actinium ions. In the latter method, actinium metal is treated with hydrogen fluoride vapors at 700 °C in an all-platinum setup. Treating actinium trifluoride with ammonium hydroxide at 900–1000 °C yields oxyfluoride AcOF. Whereas lanthanum oxyfluoride can be easily obtained by burning lanthanum trifluoride in air at 800 °C for an hour, similar treatment of actinium trifluoride yields no AcOF and only results in melting of the initial product.^[2]^[9]

AcF₃ + 2 NH₃ + H₂O → AcOF + 2 NH₄F

Actinium trichloride is obtained by reacting actinium hydroxide or oxalate with carbon tetrachloride vapors at temperatures above 960 °C. Similar to oxyfluoride, actinium oxychloride can be prepared by hydrolyzing actinium trichloride with ammonium hydroxide at 1000 °C. However, in contrast to the oxyfluoride, the oxychloride could well be synthesized by igniting a solution of actinium trichloride in hydrochloric acid with ammonia.^[2]

Reaction of aluminium bromide and actinium oxide yields actinium tribromide:

Ac₂O₃ + 2 AlBr₃ → 2 AcBr₃ + Al₂O₃

and treating it with ammonium hydroxide at 500 °C results in the oxybromide AcOBr.^[2]

Other compounds

Actinium hydride was obtained by reduction of actinium trichloride with potassium at 300 °C, and its structure was deduced by analogy with the corresponding LaH₂ hydride. The source of hydrogen in the reaction was uncertain.^[11]

Mixing monosodium phosphate (NaH₂PO₄) with a solution of actinium in hydrochloric acid yields white-colored actinium phosphate hemihydrate (AcPO₄·0.5H₂O), and heating actinium oxalate with hydrogen sulfide vapors at 1400 °C for a few minutes results in a black actinium sulfide Ac₂S₃. It may possibly be produced by acting with a mixture of hydrogen sulfide and carbon disulfide on actinium oxide at 1000 °C.^[2]

Related Research Articles

Actinium is a chemical element; it has symbol Ac and atomic number 89. It was first isolated by Friedrich Oskar Giesel in 1902, who gave it the name emanium; the element got its name by being wrongly identified with a substance André-Louis Debierne found in 1899 and called actinium. Actinium gave the name to the actinide series, a set of 15 elements between actinium and lawrencium in the periodic table. Together with polonium, radium, and radon, actinium was one of the first non-primordial radioactive elements to be isolated.

<span class="mw-page-title-main">Berkelium</span> Chemical element, symbol Bk and atomic number 97

Berkelium is a synthetic chemical element; it has symbol Bk and atomic number 97. It is a member of the actinide and transuranium element series. It is named after the city of Berkeley, California, the location of the Lawrence Berkeley National Laboratory where it was discovered in December 1949. Berkelium was the fifth transuranium element discovered after neptunium, plutonium, curium and americium.

<span class="mw-page-title-main">Lanthanum</span> Chemical element, symbol La and atomic number 57

Lanthanum is a chemical element; it has symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air. It is the eponym of the lanthanide series, a group of 15 similar elements between lanthanum and lutetium in the periodic table, of which lanthanum is the first and the prototype. Lanthanum is traditionally counted among the rare earth elements. Like most other rare earth elements, its usual oxidation state is +3, although some compounds are known with an oxidation state of +2. Lanthanum has no biological role in humans but is essential to some bacteria. It is not particularly toxic to humans but does show some antimicrobial activity.

Neodymium(III) chloride or neodymium trichloride is a chemical compound of neodymium and chlorine with the formula NdCl₃. This anhydrous compound is a mauve-colored solid that rapidly absorbs water on exposure to air to form a purple-colored hexahydrate, NdCl₃·6H₂O. Neodymium(III) chloride is produced from minerals monazite and bastnäsite using a complex multistage extraction process. The chloride has several important applications as an intermediate chemical for production of neodymium metal and neodymium-based lasers and optical fibers. Other applications include a catalyst in organic synthesis and in decomposition of waste water contamination, corrosion protection of aluminium and its alloys, and fluorescent labeling of organic molecules (DNA).

Thorium(IV) sulfide (ThS₂) is an inorganic chemical compound composed of one thorium atom ionically bonded to two atoms of sulfur. This salt is dark brown and has a melting point of 1905 °C. ThS₂ adopts the same orthorhombic lattice structure as PbCl₂.

Cerium(III) bromide is an inorganic compound with the formula CeBr₃. This white hygroscopic solid is of interest as a component of scintillation counters.

<span class="mw-page-title-main">Berkelium compounds</span> Chemical compounds

Berkelium forms a number of chemical compounds, where it normally exists in an oxidation state of +3 or +4, and behaves similarly to its lanthanide analogue, terbium. Like all actinides, berkelium easily dissolves in various aqueous inorganic acids, liberating gaseous hydrogen and converting into the trivalent oxidation state. This trivalent state is the most stable, especially in aqueous solutions, but tetravalent berkelium compounds are also known. The existence of divalent berkelium salts is uncertain and has only been reported in mixed lanthanum chloride-strontium chloride melts. Aqueous solutions of Bk³⁺ ions are green in most acids. The color of the Bk⁴⁺ ions is yellow in hydrochloric acid and orange-yellow in sulfuric acid. Berkelium does not react rapidly with oxygen at room temperature, possibly due to the formation of a protective oxide surface layer; however, it reacts with molten metals, hydrogen, halogens, chalcogens and pnictogens to form various binary compounds. Berkelium can also form several organometallic compounds.

<span class="mw-page-title-main">Actinium(III) oxide</span> Chemical compound

Actinium(III) oxide is a chemical compound containing the rare radioactive element actinium. It has the formula Ac₂O₃. It is similar to its corresponding lanthanum compound, lanthanum(III) oxide, and contains actinium in the oxidation state +3. Actinium oxide is not to be confused with Ac₂O (acetic anhydride), where Ac is an abbreviation for acetyl instead of the symbol of the element actinium.

Americium(III) fluoride or americium trifluoride is the chemical compound composed of americium and fluorine with the formula AmF₃. It is a water soluble, pink salt.

Americium(III) bromide or americium tribromide is the chemical compound composed of americium and bromine with the formula AmBr₃, with americium in a +3 oxidation state. The compound is a crystalline solid.

Many compounds of thorium are known: this is because thorium and uranium are the most stable and accessible actinides and are the only actinides that can be studied safely and legally in bulk in a normal laboratory. As such, they have the best-known chemistry of the actinides, along with that of plutonium, as the self-heating and radiation from them is not enough to cause radiolysis of chemical bonds as it is for the other actinides. While the later actinides from americium onwards are predominantly trivalent and behave more similarly to the corresponding lanthanides, as one would expect from periodic trends, the early actinides up to plutonium have relativistically destabilised and hence delocalised 5f and 6d electrons that participate in chemistry in a similar way to the early transition metals of group 3 through 8: thus, all their valence electrons can participate in chemical reactions, although this is not common for neptunium and plutonium.

Actinium(III) fluoride (AcF₃) is an inorganic compound, a salt of actinium and fluorine.

Neptunium(III) fluoride or neptunium trifluoride is a salt of neptunium and fluorine with the formula NpF₃.

Actinium(III) bromide is a radioactive white crystalline solid that is a salt of actinium. It is prepared by reacting actinium(III) oxide with aluminium bromide at 750 °C.

Actinium(III) sulfide is the radioactive compound of actinium with the formula Ac₂S₃. This salt was prepared by heating actinium(III) oxalate at 1400°C for 6 minutes in a mixture of carbon disulfide and hydrogen sulfide. The result was conformed to be actinium(III) sulfide by x-ray diffraction.

Actinium(III) phosphate is a white-colored chemical compound of the radioactive element actinium. This compound was created by reacting actinium(III) chloride with monosodium phosphate in aqueous hydrochloric acid. This resulted in the hemihydrate AcPO₄·1/2H₂O, whose structure was confirmed by x-ray diffraction to match that of lanthanum phosphate. To become anhydrous, it was heated to 700 °C, which resulted in a solid that was black (presumably due to the presence of impurities), and whose specific X-ray structure did not match that of other known correspond to other actinide phosphates.

Curium compounds are compounds containing the element curium (Cm). Curium usually forms compounds in the +3 oxidation state, although compounds with curium in the +4, +5 and +6 oxidation states are also known.

<span class="mw-page-title-main">Curium(III) bromide</span> Chemical compound

Curium(III) bromide is the bromide salt of curium. It has an orthorhombic crystal structure.

Protactinium compounds are compounds containing the element protactinium. These compounds usually have protactinium in the +5 oxidation state, although these compounds can also exist in the +2, +3 and +4 oxidation states.

References

1 2 Actinium, Great Soviet Encyclopedia (in Russian)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 Fried, Sherman; Hagemann, French; Zachariasen, W. H. (1950). "The Preparation and Identification of Some Pure Actinium Compounds". Journal of the American Chemical Society. 72 (2): 771–775. doi:10.1021/ja01158a034.
1 2 Farr, J.; Giorgi, A. L.; Bowman, M. G.; Money, R. K. (1961). "The crystal structure of actinium metal and actinium hydride". Journal of Inorganic and Nuclear Chemistry. 18: 42–47. doi:10.1016/0022-1902(61)80369-2. OSTI 4397640.
↑ Stites, Joseph G.; Salutsky, Murrell L.; Stone, Bob D. (1955). "Preparation of Actinium Metal". J. Am. Chem. Soc. 77 (1): 237–240. doi:10.1021/ja01606a085.
1 2 Zachariasen, W. H. (1949). "Crystal chemical studies of the 5f-series of elements. XII. New compounds representing known structure types". Acta Crystallographica. 2 (6): 388–390. Bibcode:1949AcCry...2..388Z. doi: 10.1107/S0365110X49001016 .
↑ Zachariasen, W. H. (1949). "Crystal chemical studies of the 5f-series of elements. VI. The Ce2S3-Ce3S4 type of structure" (PDF). Acta Crystallographica. 2 (1): 57–60. Bibcode:1949AcCry...2...57Z. doi:10.1107/S0365110X49000126. Archived (PDF) from the original on 2022-10-09.
↑ Meyer, p. 71
1 2 Zachariasen, W. H. (1948). "Crystal chemical studies of the 5f-series of elements. I. New structure types". Acta Crystallographica. 1 (5): 265–268. Bibcode:1948AcCry...1..265Z. doi: 10.1107/S0365110X48000703 .
1 2 Meyer, pp. 87–88
↑ Sherman, Fried; Hagemann, French; Zachariasen, W. H. (1950). "The Preparation and Identification of Some Pure Actinium Compounds". Journal of the American Chemical Society. 72 (2): 771–775. doi:10.1021/ja01158a034.
↑ Meyer, p. 43

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.

[bse-1] 1 2 Actinium, Great Soviet Encyclopedia (in Russian)

[j2-2] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Fried, Sherman; Hagemann, French; Zachariasen, W. H. (1950). "The Preparation and Identification of Some Pure Actinium Compounds". Journal of the American Chemical Society. 72 (2): 771–775. doi:10.1021/ja01158a034.

[ach-3] 1 2 Farr, J.; Giorgi, A. L.; Bowman, M. G.; Money, R. K. (1961). "The crystal structure of actinium metal and actinium hydride". Journal of Inorganic and Nuclear Chemistry. 18: 42–47. doi:10.1016/0022-1902(61)80369-2. OSTI 4397640.

[blueglow-4] Stites, Joseph G.; Salutsky, Murrell L.; Stone, Bob D. (1955). "Preparation of Actinium Metal". J. Am. Chem. Soc. 77 (1): 237–240. doi:10.1021/ja01606a085.

[aco-5] 1 2 Zachariasen, W. H. (1949). "Crystal chemical studies of the 5f-series of elements. XII. New compounds representing known structure types". Acta Crystallographica. 2 (6): 388–390. Bibcode:1949AcCry...2..388Z. doi: 10.1107/S0365110X49001016 .

[acs-6] Zachariasen, W. H. (1949). "Crystal chemical studies of the 5f-series of elements. VI. The Ce2S3-Ce3S4 type of structure" (PDF). Acta Crystallographica. 2 (1): 57–60. Bibcode:1949AcCry...2...57Z. doi:10.1107/S0365110X49000126. Archived (PDF) from the original on 2022-10-09.

[m71-7] Meyer, p. 71

[accl-8] 1 2 Zachariasen, W. H. (1948). "Crystal chemical studies of the 5f-series of elements. I. New structure types". Acta Crystallographica. 1 (5): 265–268. Bibcode:1948AcCry...1..265Z. doi: 10.1107/S0365110X48000703 .

[m87-9] 1 2 Meyer, pp. 87–88

[10] Sherman, Fried; Hagemann, French; Zachariasen, W. H. (1950). "The Preparation and Identification of Some Pure Actinium Compounds". Journal of the American Chemical Society. 72 (2): 771–775. doi:10.1021/ja01158a034.

[11] Meyer, p. 43

[1]

[2]

[3]

[4]

[5]

[6]

[7]

[8]

[9]

[10]

[11]