Barium is a chemical element with the symbol Ba and atomic number 56. It is the fifth element in group 2 and is a soft, silvery alkaline earth metal. Because of its high chemical reactivity, barium is never found in nature as a free element.
Selenium is a chemical element with the symbol Se and atomic number 34. It is a metalloid with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium, and also has similarities to arsenic. It seldom occurs in its elemental state or as pure ore compounds in Earth's crust. Selenium was discovered in 1817 by Jöns Jacob Berzelius, who noted the similarity of the new element to the previously discovered tellurium.
Barium carbonate is the inorganic compound with the formula BaCO3. Like most alkaline earth metal carbonates, it is a white salt that is poorly soluble in water. It occurs as the mineral known as witherite. In a commercial sense, it is one of the most important barium compounds.
Selenic acid is the inorganic compound with the formula H2SeO4. It is an oxoacid of selenium, and its structure is more accurately described as O2Se(OH)2. It is a colorless compound. Although it has few uses, one of its salts, sodium selenate is used in the production of glass and animal feeds.
Sodium selenite is the inorganic compound with the formula Na2SeO3. This salt is a colourless solid. The pentahydrate Na2SeO3(H2O)5 is the most common water-soluble selenium compound.
Selenium compounds commonly exist in the oxidation states −2, +2, +4, and +6.
Magnesium compounds are compounds formed by the element magnesium (Mg). These compounds are important to industry and biology, including magnesium carbonate, magnesium chloride, magnesium citrate, magnesium hydroxide, magnesium oxide, magnesium sulfate, and magnesium sulfate heptahydrate.
Barium sulfide is the inorganic compound with the formula BaS. BaS is the barium compound produced on the largest scale. It is an important precursor to other barium compounds including BaCO3 and the pigment lithopone, ZnS/BaSO4. Like other chalcogenides of the alkaline earth metals, BaS is a short wavelength emitter for electronic displays. It is colorless, although like many sulfides, it is commonly obtained in impure colored forms.
Barium ferrate is the chemical compound of formula BaFeO4. This is a rare compound containing iron in the +6 oxidation state. The ferrate(VI) ion has two unpaired electrons, making it paramagnetic. It is isostructural with BaSO4, and contains the tetrahedral [FeO4]2− anion.
Sodium selenide is an inorganic compound of sodium and selenium with the chemical formula Na2Se.
Managnese(II) selenide is an inorganic compound with the chemical formula MnSe.
Thullium(III) fluoride is an inorganic compound with the chemical formula TmF3.
Lutetium(III) fluoride is an inorganic compound with a chemical formula LuF3.
Europium compounds are compounds formed by the lanthanide metal europium (Eu). In these compounds, europium generally exhibits the +3 oxidation state, such as EuCl3, Eu(NO3)3 and Eu(CH3COO)3. Compounds with europium in the +2 oxidation state are also known. The +2 ion of europium is the most stable divalent ion of lanthanide metals in aqueous solution. Many europium compounds fluoresce under ultraviolet light due to the excitation of electrons to higher energy levels. Lipophilic europium complexes often feature acetylacetonate-like ligands, e.g., Eufod.
In chemistry, a selenosulfide refers to distinct classes of inorganic and organic compounds containing sulfur and selenium. The organic derivatives contain Se-S bonds, whereas the inorganic derivatives are more variable.
Lutetium compounds are compounds formed by the lanthanide metal lutetium (Lu). In these compounds, lutetium generally exhibits the +3 oxidation state, such as LuCl3, Lu2O3 and Lu2(SO4)3. Aqueous solutions of most lutetium salts are colorless and form white crystalline solids upon drying, with the common exception of the iodide. The soluble salts, such as nitrate, sulfate and acetate form hydrates upon crystallization. The oxide, hydroxide, fluoride, carbonate, phosphate and oxalate are insoluble in water.
Thulium selenide is an inorganic compound with the chemical formula Tm2Se3. It can be obtained by the reaction of thulium and selenium or thulium oxide and hydrogen selenide at high temperature, or generated in the thermal decomposition of (py)3Tm(SePh)3. In the binary system of it and antimony triselenide, TmSb3Se6, Tm6Sb8Se21, TmSbSe3 and Tm8Sb2Se15 can be formed.
Erbium selenide is an inorganic compound with a chemical formula of Er2Se3. It is an orthorhombic crystal with a Sc2S3 structure and a space group of Fddd. It can be obtained by the reaction of erbium and selenium or erbium oxide and hydrogen selenide at high temperature. It reacts with magnesium selenide at 1000 °C to obtain MgEr2Se4.
Holmium selenide is an inorganic compound with the chemical formula Ho2Se3. It can be obtained from the reaction of holmium and selenium (in the presence of iodine) or holmium oxide and hydrogen selenide at high temperature. It can form orthorhombic AgHoSe2 in the binary system of silver selenide.
Strontium selenide is an inorganic compound with the chemical formula SrSe.
