Chemistry

Tin(II) sulfide (SnS) Tin(II) sulfide Tin(II) sulfide, also called stannous sulfide, is a layered semiconductor mineral and compound of tin and sulfide; studied for thin films, photovoltaics and thermoelectrics.

Tin(IV) bromide (stannic bromide) Tin(IV) bromide An overview of tin(IV) bromide (SnBr4): composition, structure, preparation, uses, and safety notes for the tin(IV) halide.

Tin(IV) chloride (stannic chloride) Tin(IV) chloride Tin(IV) chloride, SnCl4, is a volatile molecular tin compound used as a Lewis acid and precursor to organotin compounds, tin oxides and other tin-containing materials; it hydrolyze…

Tin(IV) fluoride (stannic fluoride) — properties, structure, and uses Tin(IV) fluoride Tin(IV) fluoride (SnF4) is a tin salt in the +4 oxidation state. This entry summarizes its structure, preparation, reactions, uses in research, and safety considerations.

Tin(IV) iodide (stannic iodide, SnI4) Tin(IV) iodide Overview of tin(IV) iodide (SnI4): composition, molecular structure, preparation, reactivity, uses and safety notes for the tin(IV) halide.

Tin(IV) oxide (tin dioxide): properties, occurrence and applications Tin(IV) oxide Tin(IV) oxide (SnO2), also called tin dioxide or stannic oxide, is a white inorganic compound used as an ore of tin, a polishing agent, a gas-sensing semiconductor and a transparen…

Tin(IV) sulfide (SnS2): properties, structure and applications Tin(IV) sulfide Tin(IV) sulfide (SnS2), also called stannic sulfide, is a yellow layered semiconductor. This article summarizes its composition, structure, properties, synthesis, uses, and handlin…

Titanium Titanium is a corrosion-resistant, strong, lightweight transition metal (atomic number 22, symbol Ti) used in aerospace, medicine, pigments and industrial applications.

Titanium alloy: properties, uses and manufacturing Titanium alloy Alloys of titanium with added elements that combine high strength, low density and corrosion resistance; widely used in aerospace, medical implants and specialty engineering despit…

Titration (Volumetric Analysis): Principles, Methods, and Applications Titration Titration is a laboratory technique for determining the concentration of a solution by controlled addition of a reagent. Covers principles, equipment, indicators, calculation and c…

Toothpaste: purpose, composition, varieties, history, and safety Toothpaste An overview of toothpaste: what it is, common ingredients and types, brief history, uses and safety advice, and distinctions between formulations and flavors.

Torquoselectivity in electrocyclic reactions Torquoselectivity Torquoselectivity is the directional preference for substituent rotation in electrocyclic reactions, determining which stereoisomer or constitutional isomer forms and guiding enant…

Toxaphene (camphechlor): persistent insecticide and environmental pollutant Toxaphene Toxaphene is a complex chlorinated pesticide once used widely on crops and livestock. It is persistent, volatile, bioaccumulative and restricted under international agreements beca…

Toxic metals: causes, health effects, exposure and prevention Toxic metals Overview of toxic metals, common harmful elements, how they affect health, routes of exposure, diagnosis and treatment options, and strategies for prevention and environmental cont…

Toxicity: how substances harm organisms and how toxicology measures risk Toxicity Toxicity is the potential of a substance to cause harm to organisms. This article explains dose-dependence, measures of toxicity, factors that influence harm, historical context, a…

Trace element A chemical element present in very small concentrations in a system. Important across nutrition, geology, environment and materials science, where it may be essential, diagnostic o…

Transactinide elements Transactinide element Transactinide elements are the synthetic, highly radioactive chemical elements with atomic numbers above the actinide series (generally Z ≥ 104); they are produced in laboratories…

Transition metals: d‑block elements — properties, classification, and applications Transition metal Overview of transition (d‑block) metals: classification debates, common physical and chemical properties, oxidation states and coordination chemistry, and key biological, catalytic…

Transition state (chemistry) Transition state The transition state is the highest-energy configuration along a reaction pathway. This article explains its features, how it differs from intermediates, methods to study it, and i…

Transmutation: from alchemy to nuclear change Transmutation Transmutation is the conversion of one chemical element into another—historically a goal of alchemists and today a subject of nuclear science with natural and artificial mechanisms…

Transuranium element: elements beyond uranium in the periodic table Transuranium element Chemical elements with atomic numbers greater than 92. All are radioactive; most are synthetic and produced in reactors or accelerators. Includes neptunium, plutonium and heavier t…

Triclinic crystal system Triclinic Triclinic: the least symmetric crystal system, with three unequal, oblique axes. Common among certain minerals (e.g., copper sulfate pentahydrate) and defined by a primitive, low-s…

Trifluoromethylphenylpiperazine (TFMPP) — overview and context Trifluoromethylphenylpiperazine TFMPP is a piperazine-derived recreational psychoactive substance that affects serotonin systems. It has no approved industrial or medical uses and is often encountered as a compon…

Triglyceride (triacylglycerol): structure, role, and significance Triglyceride Triglycerides are esters of glycerol and three fatty acids; they serve as the main form of energy storage in animals and plants, are major components of dietary fats and oils, and…

Trinitrotoluene (TNT) Trinitrotoluene Trinitrotoluene (TNT) is a widely used nitroaromatic explosive notable for its stability, melt-castability, toxicological concerns, forensic detectability and role as a reference f…

Triple point (phase equilibrium) Triple point The triple point is the unique temperature and pressure at which a pure substance's solid, liquid, and gas phases coexist in equilibrium; important in thermodynamics and temperatur…

Tritium (hydrogen-3): properties, production, uses and safety Tritium Tritium (³H or T) is a radioactive hydrogen isotope used in fusion research, tracers and luminous devices. This article explains its properties, natural and artificial production,…

Tungsten (W) — Properties, Uses, and History Tungsten Tungsten (also wolfram) is a dense transition metal known for its very high melting point, hard alloys, and wide uses from lighting and electronics to heavy-duty industrial and mil…

Turpentine — natural solvent and source of terpenes Turpentine Turpentine is a volatile solvent produced by distilling tree resin, mainly from pines. Composed chiefly of terpene hydrocarbons, it is used in paints, varnishes and chemical synthe…

Tyrosine: an aromatic amino acid important in proteins and metabolism Tyrosine Tyrosine (Tyr, Y) is a non-essential, aromatic amino acid used in protein synthesis and as a precursor for neurotransmitters, thyroid hormones, pigments and many plant metabolites.

Ultramarine (deep blue pigment and colour) Ultramarine Ultramarine is a vivid blue pigment originally from lapis lazuli (lazurite). Its colour comes from sulfur anions; a cheaper synthetic form was developed in the 19th century and it…

Ultraviolet–visible absorption Process by which molecules absorb ultraviolet or visible light to promote electrons to excited states; basis of UV–Vis spectroscopy used in chemistry, biology, and materials scienc…

Unbinilium (element 120) Unbinilium Unbinilium (temporary symbol Ubn, Z=120) is a hypothetical, not-yet-discovered element predicted to be a group 2 alkaline‑earth metal in period 8. It is the subject of theoretical…

Unbioctium (element 128) — proposed superheavy element Unbioctium Unbioctium (Ubo) is the temporary name for the not-yet-discovered element with atomic number 128, predicted to lie in the superactinide region; properties and isotopes remain theor…

Unbipentium (Ubp) — hypothetical element with atomic number 125 Unbipentium Unbipentium (Ubp) is the temporary name for the predicted element with atomic number 125. It is a theoretical superactinide and a candidate g-block member; synthesis attempts have…

Unbiunium (Ubu) — hypothetical element with atomic number 121 Unbiunium Unbiunium (temporary symbol Ubu) is a predicted element with atomic number 121, placed in the proposed superactinide series. It remains hypothetical and has not yet been synthesize…

Universal indicator: composition, uses, and limitations Universal indicator A universal indicator is a mixture of pH-sensitive dyes that produces a continuous spectrum of colors to estimate the acidity or alkalinity of aqueous solutions.

Ununennium (Element 119): predicted properties, synthesis attempts, and significance Ununennium Ununennium (element 119, temporary symbol Uue) is the not-yet-synthesized next alkali metal; this article summarizes its expected properties, production challenges, history of atte…

Uranium: properties, isotopes, uses, history, and safety Uranium Comprehensive overview of uranium: its physical and nuclear properties, principal isotopes, geological occurrence, uses in energy and weapons, historical discovery, and health and…

Uranium trioxide (UO3) — properties, production, uses, and hazards Uranium trioxide Uranium trioxide (UO3) is a hexavalent oxide of uranium used as an intermediate in the nuclear fuel cycle. This article summarizes its properties, preparation, applications, and sa…

Uranium-235: fissile isotope used in reactors and weapons Uranium-235 Uranium-235 (U-235) is a naturally occurring, fissile isotope of uranium used as nuclear fuel, in early atomic weapons, and in scientific research; it has distinctive nuclear prope…

Uranyl nitrate Uranyl nitrate is a water‑soluble uranium(VI) salt used as a reagent and intermediate in uranium chemistry; it is radioactive and chemically toxic and appears as yellow crystalline…

Urea (carbamide): chemistry, biological role, uses and history Urea Urea (CO(NH2)2), also called carbamide, is a simple nitrogenous organic compound produced by animals and manufactured for fertilizers, resins, cosmetics, automotive emissions and c…

Uric acid: chemistry, biology, and clinical significance Uric acid An overview of uric acid — its chemical nature, how it is produced and excreted, clinical implications such as gout and kidney stones, and its role in evolution and medicine.

Valence (chemistry, linguistics, and psychology) Valence Valence denotes a capacity to connect or carry evaluative weight: in chemistry an atom's combining power, in linguistics a verb's argument structure, and in psychology the positive…

Valence electron An overview of valence electrons: definition, role in bonding and reactivity, determination from electron configuration and the periodic table, historical context, exceptions, and…

Valency (valence) in chemistry: definition, history, and distinctions Valency Valency (valence) is the number of chemical bonds an atom typically forms. This article explains definitions, examples, historical development, related concepts (oxidation state, v…

Valentinite (Sb2O3): mineral form of antimony trioxide Valentinite Valentinite is a naturally occurring Sb2O3 mineral formed by oxidation of stibnite. It is a soft, dense, colorless-to-white mineral of interest to collectors and a minor antimony o…