Polonium trioxide (also known as polonium(VI) oxide) is a chemical compound with the formula Po O₃. It is one of three

oxide An oxide () is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– (molecular) ion. with oxygen in the oxidation state of −2. Most of the E ...

s of polonium, the other two being

polonium monoxide Polonium monoxide (also known as polonium(II) oxide) is a chemical compound with the formula Po O. It is one of three oxides of polonium, the other two being polonium dioxide (PoO2) and polonium trioxide (PoO3). It is an interchalcogen. Appeara ...

(PoO) and

polonium dioxide Polonium dioxide (also known as polonium(IV) oxide) is a chemical compound with the formula Po O2. It is one of three oxides of polonium, the other two being polonium monoxide (PoO) and polonium trioxide (PoO3). It is a pale yellow crystalline ...

(PoO₂). It is an

interchalcogen The chalcogens react with each other to form interchalcogen compounds. Although no chalcogen is extremely electropositive,This article uses Pauling electronegativity throughout. nor quite as electronegative as the halogen fluorine (the most elect ...

. It has so far only been detected in trace amounts.

Preparation

It has been reported that trace quantities of polonium trioxide form during the anodic deposition of polonium from

acid In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...

ic solutions. Although there is no experimental evidence for this, the fact that the deposit dissolves in

hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3%� ...

suggests that it contains polonium in a high

oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. C ...

. It has been predicted that polonium trioxide may be formed by heating

and

chromium trioxide Chromium trioxide (also known as chromium(VI) oxide or chromic anhydride) is an inorganic compound with the formula CrO3. It is the acidic anhydride of chromic acid, and is sometimes marketed under the same name. This compound is a dark-purple ...

together in air.

Difficulty of preparation of polonium(VI) compounds

It is very difficult to

oxidize Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...

polonium beyond Po(IV); for example, the only hexa

halide In chemistry, a halide (rarely halogenide) is a binary chemical compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative (or more electropositive) than the halogen, to make a fluor ...

of polonium is the

hexafluoride A hexafluoride is a chemical compound with the general formula QXnF6, QXnF6m−, or QXnF6m+. Many molecules fit this formula. An important hexafluoride is hexafluorosilicic acid (H2SiF6), which is a byproduct of the mining of phosphate rock. In ...

, PoF₆, and fluorine is already the most

electronegative Electronegativity, symbolized as , is the tendency for an atom of a given chemical element to attract shared electrons (or electron density) when forming a chemical bond. An atom's electronegativity is affected by both its atomic number and the d ...

element (though polonium hexaiodide was once reportedly formed in the vapour phase, it immediately decomposed). However, the difficulty in obtaining polonium trioxide and polonates (containing the

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

, analogous to sulfate, selenate, and

tellurate In chemistry tellurate is a compound containing an oxyanion of tellurium where tellurium has an oxidation number of +6. In the naming of inorganic compounds it is a suffix that indicates a polyatomic anion with a central tellurium atom.

) by direct oxidation of Po(IV) compounds may be due to the fact that

polonium-210 Polonium-210 (210Po, Po-210, historically radium F) is an isotope of polonium. It undergoes alpha decay to stable 206Pb with a half-life of 138.376 days (about months), the longest half-life of all naturally occurring polonium isotopes. First i ...

, while the most easily available

isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) ...

of polonium, is strongly radioactive. Similar work with

curium Curium is a transuranic, radioactive chemical element with the symbol Cm and atomic number 96. This actinide element was named after eminent scientists Marie and Pierre Curie, both known for their research on radioactivity. Curium was first inte ...

shows that it is easier to achieve higher oxidation states with longer-lived isotopes; thus, it may be easier to obtain Po(VI) (especially polonium trioxide) using the longer-lived

polonium-208 Polonium (84Po) has 42 isotopes, all of which are radioactive, with between 186 and 227 nucleons. 210Po with a half-life of 138.376 days has the longest half-life of naturally occurring polonium. 209Po, with a half-life of 125.2 years, has the lo ...

or polonium-209. It has been suggested that Po(VI) might be more stabilized in anions such as or , like other high oxidation states.

References

{{Polonium compounds Polonium compounds Oxides Interchalcogens