Tantalum
Tantalum is a hard, blue-grey transition metal, atomic number 73. Extremely corrosion resistant - resistant to virtually all acids at room temperature. Biocompatible. Critical mate…
Chemical Glossary — Letter T
41 chemicals found starting with "T"
Tautomerism
Tautomerism is a phenomenon in which a compound exists as two or more interconvertible structural isomers (tautomers) that are in rapid equilibrium. The most common type is keto-en…
Technetium
Technetium is a silvery-grey transition metal, atomic number 43, the lightest element with no stable isotopes. First artificially produced element (1937, Lawrence Berkeley Lab). Al…
Tellurium
Tellurium is a brittle, mildly toxic metalloid, atomic number 52. Rare in Earth crust. Imparts a distinct garlic-like odour to breath and sweat even at trace exposures (tellurium b…
Temperature
A measure of the average kinetic energy of particles in a substance. Measured in Celsius (°C), Fahrenheit (°F), or Kelvin (K). The Kelvin scale (absolute temperature) is used in sc…
Tennessine
Tennessine is a synthetic radioactive element named after Tennessee, USA. First synthesised in 2010 through collaboration between Dubna and Oak Ridge National Laboratory. Expected …
Terbium
Terbium is a soft, silvery-white rare earth metal, atomic number 65. Used in green phosphors for energy-efficient lighting and displays. Terfenol-D (TbDyFe) is a highly magnetostri…
Termolecular Reaction
A termolecular reaction is an elementary reaction step in which three reactant particles (molecules, atoms, or ions) collide simultaneously to form products. Such reactions are ext…
Ternary Acid
A ternary acid (oxyacid) is an acid composed of three elements: hydrogen, oxygen, and a third element (usually a nonmetal such as sulfur, nitrogen, phosphorus, or chlorine). Exampl…
Ternary Compound
A ternary compound is a chemical compound composed of exactly three different elements. Examples include sodium hydroxide (NaOH, Na + O + H), calcium carbonate (CaCO₃, Ca + C + O),…
Tetrahedral
Tetrahedral is a molecular geometry in which a central atom is bonded to four other atoms positioned at the corners of a regular tetrahedron, giving bond angles of approximately 10…
Thallium
Thallium is a soft, grey post-transition metal, atomic number 81. Extremely toxic - tasteless, odourless thallium salts have been used as rat poison and murder weapon. Thallium-201…
Theoretical Yield
The maximum amount of product that could be formed from the given amounts of reactants, calculated from stoichiometry assuming 100% reaction. The actual yield is always less than o…
Theoretical Yield
The theoretical yield is the maximum amount of product that can be formed from a given amount of limiting reactant in a chemical reaction, assuming complete reaction and no losses.…
Thermal Cracking
Thermal cracking is a petroleum refining process in which large hydrocarbon molecules (found in heavy fractions of crude oil) are broken into smaller, more valuable molecules by th…
Thermal Decomposition
A chemical reaction in which a compound breaks down into simpler substances upon heating. Examples include the decomposition of calcium carbonate (CaCO₃ → CaO + CO₂) and metal carb…
Thermal Equilibrium
Thermal equilibrium is the condition in which two objects in thermal contact no longer exchange heat because they have reached the same temperature. It is the basis of the Zeroth L…
Thermocouple
A temperature-sensing device consisting of two different metal wires joined at one end. The temperature difference between the hot and cold junctions generates a voltage (Seebeck e…
Thermodynamics
The branch of science dealing with heat, work, energy transformations, and the relationships between properties of matter (temperature, pressure, volume). The four laws of thermody…
Thermodynamics
Thermodynamics is the branch of physical science that deals with the relationships between heat, work, temperature, and energy. Its four laws govern the direction and extent of che…
Thermonuclear Energy
Thermonuclear energy is the energy released by nuclear fusion reactions — the combining of light atomic nuclei (such as deuterium and tritium) at extremely high temperatures (tens …
Third Law of Thermodynamics
The Third Law of Thermodynamics states that the entropy of a perfect crystalline substance approaches zero as the temperature approaches absolute zero (0 K). This provides an absol…
Thorium
Thorium is a weakly radioactive actinide metal. It is about three times more abundant than uranium in Earth crust and is considered a potential future nuclear fuel in thorium react…
Thulium
Thulium is a soft, silvery rare earth metal, atomic number 69. The least abundant naturally occurring lanthanide. Tm-170 is a portable X-ray source used in medicine and industry. T…
Tin
Tin is a silvery, malleable post-transition metal, atomic number 50. Has two allotropes: grey tin (alpha, brittle, below 13.2 C) and white tin (beta, normal form). Used since antiq…
Titanium
Titanium is a lustrous, silvery transition metal, atomic number 22. Renowned for its excellent strength-to-weight ratio, corrosion resistance, and biocompatibility. Fourth most abu…
Titrant
The solution of known concentration added from a burette during a titration. The titrant reacts with the analyte in the flask. Common titrants include sodium hydroxide (for acid-ba…
Titration
Titration is a quantitative analytical technique in which a solution of known concentration (titrant, in a burette) is gradually added to a solution of unknown concentration (analy…
Titration
A quantitative analytical technique in which a solution of known concentration (titrant) is added to a known volume of solution of unknown concentration (analyte) until the reactio…
Titration Curve
A titration curve is a graph of pH (or potential) versus volume of titrant added during a titration. It shows how the pH changes as titrant is added, revealing the equivalence poin…
Total Ionic Equation
A total (complete) ionic equation is a representation of a chemical reaction in solution in which all strong electrolytes are written as their individual dissociated ions. It shows…
Tracer
A tracer is a substance (radioactive isotope or stable heavy isotope) used to follow the path of an element or compound through a chemical or biological system. Radioactive tracers…
Transition Metal
An element in groups 3-12 of the periodic table, defined by IUPAC as elements whose atoms or ions have incompletely filled d-subshells. Transition metals often form colored compoun…
Transition State
The highest-energy species along a reaction coordinate, occurring at the activation energy maximum. Unlike intermediates, transition states cannot be isolated. They involve partial…
Transition State Theory
Transition state theory (activated complex theory) proposes that chemical reactions proceed through an unstable, high-energy intermediate structure called the transition state (or …
Transuranium Elements
Transuranium elements (also called transuranic elements) are the chemical elements with atomic numbers greater than 92 (uranium). All transuranium elements are radioactive and most…
Triple Bond
A covalent bond formed by three pairs of shared electrons between two atoms: one sigma bond and two pi bonds. Triple bonds are shorter and stronger than double or single bonds. Alk…
Triple Point
The unique combination of temperature and pressure at which all three phases (solid, liquid, and gas) of a substance coexist in equilibrium. The triple point of water (273.16 K, 61…
Tungsten
Tungsten is a hard, grey transition metal, atomic number 74. Has the highest melting point of all metals (3422 C) and the highest tensile strength at temperatures above 1650 C. Use…
Tyndall Effect
The scattering of light by colloidal particles, making the light beam visible. Colloids exhibit the Tyndall effect, while true solutions do not (particles too small to scatter ligh…
Tyndall Effect
The phenomenon whereby light is scattered by particles in a colloid, making the beam visible. Named after John Tyndall who described it in 1869. This effect distinguishes colloidal…
About Chemicals Starting With T
This page lists all chemicals in our database beginning with the letter T. Each entry provides the chemical formula, CAS registry number, physical and chemical properties, common uses, and safety information. Use the alphabetical navigation above to browse other letters, or use the search function to find a specific chemical quickly.
Our chemical glossary covers acids, bases, salts, organic compounds, inorganic compounds, solvents, and many more categories. Click on any chemical name to view its full detailed profile.