Europium is a chemical element; it has symbol Eu and atomic number 63. Europium is a silvery-white metal of the lanthanide series that reacts readily with air to form a dark oxide coating. It is the most chemically reactive, least dense, and softest of the lanthanide elements. It is soft enough to be cut with a knife. Europium was isolated in 1901 and named after the continent of Europe. Europium usually assumes the oxidation state +3, like other members of the lanthanide series, but compounds having oxidation state +2 are also common. All europium compounds with oxidation state +2 are slightly reducing. Europium has no significant biological role and is relatively non-toxic compared to other heavy metals. Most applications of europium exploit the phosphorescence of europium compounds. Europium is one of the rarest of the rare-earth elements on Earth.
Iron(III) oxide or ferric oxide is the inorganic compound with the formula Fe2O3. It is one of the three main oxides of iron, the other two being iron(II) oxide (FeO), which is rare; and iron(II,III) oxide (Fe3O4), which also occurs naturally as the mineral magnetite. As the mineral known as hematite, Fe2O3 is the main source of iron for the steel industry. Fe2O3 is readily attacked by acids. Iron(III) oxide is often called rust, since rust shares several properties and has a similar composition; however, in chemistry, rust is considered an ill-defined material, described as hydrous ferric oxide.
Copper(I) oxide or cuprous oxide is the inorganic compound with the formula Cu2O. It is one of the principal oxides of copper, the other being copper(II) oxide or cupric oxide (CuO). Cuprous oxide is a red-coloured solid and is a component of some antifouling paints. The compound can appear either yellow or red, depending on the size of the particles. Copper(I) oxide is found as the reddish mineral cuprite.
Copper(II) oxide or cupric oxide is an inorganic compound with the formula CuO. A black solid, it is one of the two stable oxides of copper, the other being Cu2O or copper(I) oxide (cuprous oxide). As a mineral, it is known as tenorite. It is a product of copper mining and the precursor to many other copper-containing products and chemical compounds.
Sodium perchlorate is an inorganic compound with the chemical formula NaClO4. It consists of sodium cations Na+ and perchlorate anions ClO−4. It is a white crystalline, hygroscopic solid that is highly soluble in water and ethanol. It is usually encountered as sodium perchlorate monohydrate NaClO4·H2O. The compound is noteworthy as the most water-soluble of the common perchlorate salts.
Tin(II) oxide is a compound with the formula SnO. It is composed of tin and oxygen where tin has the oxidation state of +2. There are two forms, a stable blue-black form and a metastable red form.
Vanadium(III) chloride describes the inorganic compound with the formula VCl3 and its hydrates. It forms a purple anhydrous form and a green hexahydrate [VCl2(H2O)4]Cl·2H2O. These hygroscopic salts are common precursors to other vanadium(III) complexes and is used as a mild reducing agent.
Vanadium(III) fluoride is the chemical compound with the formula VF3. This yellow-green, refractory solid is obtained in a two-step procedure from V2O3. Similar to other transition-metal fluorides (such as MnF2), it exhibits magnetic ordering at low temperatures (e.g. V2F6.4H2O orders below 12 K).
Ferric acetate is the acetate salt of the coordination complex [Fe3O(OAc)6(H2O)3]+ (OAc− is CH3CO2−). Commonly the salt is known as "basic iron acetate". The formation of the red-brown complex was once used as a test for ferric ions.
Cobalt(III) oxide is the inorganic compound with the formula of Co2O3. Although only two oxides of cobalt are well characterized, CoO and Co3O4, procedures claiming to give Co2O3 have been described. Thus treatment of Co(II) salts such as cobalt(II) sulfate with an aqueous solution of sodium hypochlorite (also known as bleach) gives a black solid:
Cobalt(II) carbonate is the inorganic compound with the formula CoCO3. This reddish paramagnetic solid is an intermediate in the hydrometallurgical purification of cobalt from its ores. It is an inorganic pigment, and a precursor to catalysts. Cobalt(II) carbonate also occurs as the rare red/pink mineral spherocobaltite.
Cobalt(II) iodide or cobaltous iodide are the inorganic compounds with the formula CoI2 and the hexahydrate CoI2(H2O)6. These salts are the principal iodides of cobalt.
Cobalt(II,III) oxide is an inorganic compound with the formula Co3O4. It is one of two well characterized cobalt oxides. It is a black antiferromagnetic solid. As a mixed valence compound, its formula is sometimes written as CoIICoIII2O4 and sometimes as CoO•Co2O3.
Cobalt(II) hydroxide or cobaltous hydroxide is the inorganic compound with the formula Co(OH)
2, consisting of divalent cobalt cations Co2+
and hydroxide anions OH−
. The pure compound, often called the "beta form" is a pink solid insoluble in water.
The Nickel oxyacid salts are a class of chemical compounds of nickel with an oxyacid. The compounds include a number of minerals and industrially important nickel compounds.
The nickel organic acid salts are organic acid salts of nickel. In many of these the ionised organic acid acts as a ligand.
An yttrium compound is a chemical compound containing yttrium. Among these compounds, yttrium generally has a +3 valence. The solubility properties of yttrium compounds are similar to those of the lanthanides. For example oxalates and carbonates are hardly soluble in water, but soluble in excess oxalate or carbonate solutions as complexes are formed. Sulfates and double sulfates are generally soluble. They resemble the "yttrium group" of heavy lanthanide elements.
Mohindar Singh Seehra is an Indian-American Physicist, academic and researcher. He is Eberly Distinguished Professor Emeritus at West Virginia University (WVU).
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.
Cobalt compounds are chemical compounds formed by cobalt with other elements.
