Lanthanum is a chemical element with the symbol La and the 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 used by some bacteria. It is not particularly toxic to humans but does show some antimicrobial activity.
The lanthanide or lanthanoid series of chemical elements comprises at least the 14 metallic chemical elements with atomic numbers 57–70, from lanthanum through ytterbium. In the periodic table, they fill the 4f orbitals. Lutetium is also sometimes considered a lanthanide, despite being a d-block element and a transition metal.
Praseodymium is a chemical element; it has symbol Pr and the atomic number 59. It is the third member of the lanthanide series and is considered one of the rare-earth metals. It is a soft, silvery, malleable and ductile metal, valued for its magnetic, electrical, chemical, and optical properties. It is too reactive to be found in native form, and pure praseodymium metal slowly develops a green oxide coating when exposed to air.
Stearic acid is a saturated fatty acid with an 18-carbon chain. The IUPAC name is octadecanoic acid. It is a soft waxy solid with the formula CH3(CH2)16CO2H. The triglyceride derived from three molecules of stearic acid is called stearin. Stearic acid is a prevalent fatty-acid in nature, found in many animal and vegetable fats, but is usually higher in animal fat than vegetable fat. It has a melting point of 69.4 °C (156.9 °F) °C and a pKa of 4.50.
Polymer degradation is the reduction in the physical properties of a polymer, such as strength, caused by changes in its chemical composition. Polymers and particularly plastics are subject to degradation at all stages of their product life cycle, including during their initial processing, use, disposal into the environment and recycling. The rate of this degradation varies significantly; biodegradation can take decades, whereas some industrial processes can completely decompose a polymer in hours.
Thorium dioxide (ThO2), also called thorium(IV) oxide, is a crystalline solid, often white or yellow in colour. Also known as thoria, it is mainly a by-product of lanthanide and uranium production. Thorianite is the name of the mineralogical form of thorium dioxide. It is moderately rare and crystallizes in an isometric system. The melting point of thorium oxide is 3300 °C – the highest of all known oxides. Only a few elements (including tungsten and carbon) and a few compounds (including tantalum carbide) have higher melting points. All thorium compounds, including the dioxide, are radioactive because there are no stable isotopes of thorium.
Polymer stabilizers are chemical additives which may be added to polymeric materials to inhibit or retard their degradation. Mainly they protect plastic and rubber products against heat, oxidation, and UV light. The biggest quantity of stabilizers is used for polyvinyl chloride (PVC), as the production and processing of this type of plastic would not be possible without stabilizing chemicals. Common polymer degradation processes include oxidation, UV-damage, thermal degradation, ozonolysis, combinations thereof such as photo-oxidation, as well as reactions with catalyst residues, dyes, or impurities. All of these degrade the polymer at a chemical level, via chain scission, uncontrolled recombination and cross-linking, which adversely affects many key properties such as strength, malleability, appearance and colour.
Cadmium stearate is a salt with the formula Cd(O2CC17H35)2. Classified as a metallic soap, this a white solid is used as a lubricant and as a heat- and light-stabilizer in polyvinyl chloride. The use of cadmium stearate is being phased out because of its toxicity.
Lanthanum(III) nitrate is any inorganic compound with the chemical formula La(NO3)3·xH2O. It is used in the extraction and purification of lanthanum from its ores.
Lanthanum phosphide is an inorganic compound of lanthanum and phosphorus with the chemical formula LaP.
Lanthanum(III) iodide is an inorganic compound containing lanthanum and iodine with the chemical formula LaI
3.
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. In particular, the lattice constants of the analogous lanthanum and actinium compounds differ by only a few percent.
Silver stearate is a metal-organic compound with the chemical formula C
18H
36AgO
2. The compound is classified as a metallic soap, i.e. a metal derivative of a fatty acid.
Zirconium stearate is a metal-organic compound, a salt of zirconium and stearic acid with the chemical formula C
72H
140ZrO
8.
Cerium stearate is a metal-organic compound, a salt of cerium and stearic acid with the chemical formula C
54H
105CeO
6. The compound is classified as a metallic soap, i.e. a metal derivative of a fatty acid.
Manganese stearate is a metal-organic compound, a salt of manganese and stearic acid with the chemical formula C
36H
70MnO
4. The compound is classified as a metallic soap, i.e. a metal derivative of a fatty acid.
Lead stearate is a metal-organic compound, a salt of lead and stearic acid with the chemical formula C
36H
70PbO
4. The compound is classified as a metallic soap, i.e. a metal derivative of a fatty acid. The compound is toxic.
Caesium stearate is a metal-organic compound, a salt of caesium and stearic acid with the chemical formula C
18H
35CsO
2. The compound is classified as a metallic soap, i.e. a metal derivative of a fatty acid.
Iron(III) stearate is a metal-organic compound, a salt of iron and stearic acid with the chemical formula Fe(C
17H
35COO
)3.
Lanthanum oxalate is an inorganic compound, a salt of lanthanum metal and oxalic acid with the chemical formula La
2(C
2O
4)
3.
