IUPAC in the context of End group

In chemistry, a solution is defined by IUPAC as "A liquid or solid phase containing more than one substance, when for convenience one (or more) substance, which is called the solvent, is treated differently from the other substances, which are called solutes. When, as is often but not necessarily the case, the sum of the mole fractions of solutes is small compared with unity, the solution is called a dilute solution. A superscript attached to the ∞ symbol for a property of a solution denotes the property in the limit of infinite dilution." One parameter of a solution is the concentration, which is a measure of the amount of solute in a given amount of solution or solvent. The term "aqueous solution" is used when one of the solvents is water.

Epoxy is the family of basic components or cured end products of epoxy resins, also known as polyepoxides, a class of reactive prepolymers and polymers which contain epoxide groups. The epoxide functional group is also collectively called epoxy. The IUPAC name for an epoxide group is an oxirane.

Epoxy resins may be reacted (cross-linked) either with themselves through catalytic homopolymerisation, or with a wide range of co-reactants including polyfunctional amines, acids (and acid anhydrides), phenols, alcohols and thiols (sometimes called mercaptans). These co-reactants are often referred to as hardeners or curatives, and the cross-linking reaction is commonly referred to as curing.

Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula SO
₂. It is a colorless gas with a pungent smell that is responsible for the odor of burnt matches. It is released naturally by volcanic activity and is produced as a by-product of metals refining and the burning of sulfur-bearing hydrocarbon fuels.

Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula C₂H₄ or H₂C=CH₂. It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon–carbon double bonds).

Ethylene is widely used in the chemical industry, and its worldwide production (over 225 million tonnes in 2022) exceeds that of any other organic compound. Much of this production goes toward creating polyethylene, which is a widely used plastic containing polymer chains of ethylene units in various chain lengths. Production emits greenhouse gases, including methane from feedstock production and carbon dioxide from any non-sustainable energy used.

The halogens (/ˈhælədʒən, ˈheɪ-, -loʊ-, -ˌdʒɛn/) are a group in the periodic table consisting of six chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and the radioactive elements astatine (At) and tennessine (Ts), though some authors would exclude tennessine as its chemistry is unknown and is theoretically expected to be more like that of gallium. In the modern IUPAC nomenclature, this group is known as group 17.

The word "halogen" means "salt former" or "salt maker". When halogens react with metals, they produce a wide range of salts, including calcium fluoride, sodium chloride (common table salt), silver bromide, and potassium iodide.

Caesium (IUPAC spelling; also spelled cesium in American English) is a chemical element; it has symbol Cs and atomic number 55. It is a soft, silvery-golden alkali metal with a melting point of 28.5 °C (83.3 °F; 301.6 K), which makes it one of only five elemental metals that are liquid at or near room temperature. Caesium has physical and chemical properties similar to those of rubidium and potassium. It is pyrophoric and reacts with water even at −116 °C (−177 °F). It is the least electronegative stable element, with a value of 0.79 on the Pauling scale. It has only one stable isotope, caesium-133. Caesium is mined mostly from pollucite. Caesium-137, a fission product, is extracted from waste produced by nuclear reactors. It has the largest atomic radius of all elements whose radii have been measured or calculated, at about 260 picometres.

The German chemist Robert Bunsen and physicist Gustav Kirchhoff discovered caesium in 1860 by the newly developed method of flame spectroscopy. The first small-scale applications for caesium were as a "getter" in vacuum tubes and in the light-sensitive anodes of photoelectric cells. Caesium is widely used in highly accurate atomic clocks. In 1967, the International System of Units began using a specific hyperfine transition of neutral caesium-133 atoms to define the basic unit of time, the second.

In chemistry, the hydron, informally called proton, is the cationic form of atomic hydrogen, represented with the symbol H. The general term "hydron", endorsed by IUPAC, encompasses cations of hydrogen regardless of isotope: thus it refers collectively to protons (H) for the protium isotope, deuterons (H or D) for the deuterium isotope, and tritons (H or T) for the tritium isotope.

Unlike most other ions, the hydron consists only of a bare atomic nucleus. The negatively charged counterpart of the hydron is the hydride anion, H
.

Azo compounds are organic compounds bearing the functional group diazenyl (R−N=N−R′, in which R and R′ can be either aryl or alkyl groups).

IUPAC defines azo compounds as: "Derivatives of diazene (diimide), HN=NH, wherein both hydrogens are substituted by hydrocarbyl groups, e.g. PhN=NPh azobenzene or diphenyldiazene.", where Ph stands for phenyl group. The more stable derivatives contain two aryl groups. The N=N group is called an azo group (from French azote 'nitrogen', from Ancient Greek ἀ- (a-) 'not' and ζωή (zōē) 'life').

Group 8 is a group (column) of chemical elements in the periodic table. It consists of iron (Fe), ruthenium (Ru), osmium (Os) and hassium (Hs). "Group 8" is the modern standard designation for this group, adopted by the IUPAC in 1990. It should not be confused with "group VIIIA" in the CAS system, which is group 18 (current IUPAC), the noble gases. In the older group naming systems, this group was combined with groups 9 and 10 and called group "VIIIB" in the Chemical Abstracts Service (CAS) "U.S. system", or "VIII" in the old IUPAC (pre-1990) "European system" (and in Mendeleev's original table). The elements in this group are all transition metals that lie in the d-block of the periodic table.

While groups (columns) of the periodic table are usually named after their lightest member (as in "the oxygen group" for group 16), iron group has historically been used differently; most often, it means a set of adjacent elements on period (row) 4 of the table that includes iron, such as chromium, manganese, iron, cobalt, and nickel, or only the last three, or some other set, depending on the context.

Trinitrotoluene (/traɪˌnaɪtroʊˈtɒljuːˌiːn, -jəˌwiːn/ try-NY-troh-TOL-yoo-een, -⁠yə-ween), more commonly known as TNT (and more specifically 2,4,6-trinitrotoluene, and by its preferred IUPAC name 2-methyl-1,3,5-trinitrobenzene), is a chemical compound with the formula C₆H₂(NO₂)₃CH₃. TNT is occasionally used as a reagent in chemical synthesis, but it is best known as an explosive material with convenient handling properties. The explosive yield of TNT is considered to be the standard comparative convention of bombs and asteroid impacts. In chemistry, TNT is used to generate charge transfer salts.

The dalton or unified atomic mass unit (symbols: Da or u, respectively) is a unit of mass defined as ⁠1/12⁠ of the mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state and at rest. It is a non-SI unit accepted for use with SI. The word "unified" emphasizes that the definition was accepted by both IUPAP and IUPAC. The atomic mass constant, denoted m_u, is an atomic-scale reference mass, defined identically, but it is not a unit of mass. Expressed in terms of m_a(C), the atomic mass of carbon-12: m_u = m_a(C)/12 = 1 Da. The dalton's numerical value in terms of the fixed-h kilogram is an experimentally determined quantity that, along with its inherent uncertainty, is updated periodically. As listed in the 9th edition, version 3.02, of the SI Brochure, the 2022 CODATA recommended value of the atomic mass constant expressed in the SI base unit kilogram is:

The previous value given for the dalton (1 Da = 1 u = m_u) was the 2018 CODATA recommended value:

In chemistry, a glycoside /ˈɡlaɪkəsaɪd/ is a molecule in which a sugar is bound to another functional group via a glycosidic bond. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. These can be activated by enzyme hydrolysis, which causes the sugar part to be broken off, making the chemical available for use. Many such plant glycosides are used as medications. Several species of Heliconius butterfly are capable of incorporating these plant compounds as a form of chemical defense against predators. In animals and humans, poisons are often bound to sugar molecules as part of their elimination from the body.

In formal terms, a glycoside is any molecule in which a sugar group is bonded through its anomeric carbon to another group via a glycosidic bond. Glycosides can be linked by an O- (an O-glycoside), N- (a glycosylamine), S-(a thioglycoside), or C- (a C-glycoside) glycosidic bond. According to the IUPAC, the name "C-glycoside" is a misnomer; the preferred term is "C-glycosyl compound". The given definition is the one used by IUPAC, which recommends the Haworth projection to correctly assign stereochemical configurations.

Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic. It is a polymer, primarily used for packaging (plastic bags, plastic films, geomembranes and containers including bottles, cups, jars, etc.). As of 2017, over 100 million tonnes of polyethylene resins are being produced annually, accounting for 34% of the total plastics market.

Sodium stearate (IUPAC: sodium octadecanoate) is the sodium salt of stearic acid. This white solid is the most common soap. It is found in many types of solid deodorants, rubbers, latex paints, and inks. It is also a component of some food additives and food flavorings.

In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group (−OH) of that acid is replaced by an organyl group (R′). These compounds contain a distinctive functional group. Analogues derived from oxygen replaced by other chalcogens belong to the ester category as well. According to some authors, organyl derivatives of acidic hydrogen of other acids are esters as well (e.g. amides), but not according to the IUPAC.

Glycerides are fatty acid esters of glycerol; they are important in biology, being one of the main classes of lipids and comprising the bulk of animal fats and vegetable oils. Lactones are cyclic carboxylic esters; naturally occurring lactones are mainly 5- and 6-membered ring lactones. Lactones contribute to the aroma of fruits, butter, cheese, vegetables like celery and other foods.

Group 11, by modern IUPAC numbering, is a group of chemical elements in the periodic table, consisting of copper (Cu), silver (Ag), gold (Au), and roentgenium (Rg), although no chemical experiments have yet been carried out to confirm that roentgenium behaves like the heavier homologue to gold. Group 11, more specifically, the first three members are also known as the coinage metals, due to their usage in minting coins—while the rise in metal prices mean that silver and gold are no longer used for circulating currency, remaining in use for bullion, copper remains a common metal in coins to date, either in the form of copper clad coinage or as part of the cupronickel alloy. They were most likely the first three elements discovered. Copper, silver, and gold all occur naturally in elemental form.

Oganesson is a synthetic chemical element; it has symbol Og and atomic number 118. It was first synthesized in 2002 at the Joint Institute for Nuclear Research (JINR) in Dubna, near Moscow, Russia, by a joint team of Russian and American scientists. In December 2015, it was recognized as one of four new elements by the Joint Working Party of the international scientific bodies IUPAC and IUPAP. It was formally named on 28 November 2016. The name honors the nuclear physicist Yuri Oganessian, who played a leading role in the discovery of the heaviest elements in the periodic table.

Oganesson has the highest atomic number and highest atomic mass of all known elements. On the periodic table of the elements it is a p-block element, a member of group 18, and the last member of period 7. Its only known isotope, oganesson-294, is highly radioactive, with a half-life of 0.7 ms and, as of 2025, only five atoms have been successfully produced. This has so far prevented any experimental studies of its chemistry. Because of relativistic effects, theoretical studies predict that it would be a solid at room temperature, and significantly reactive, unlike the other members of group 18 (the noble gases).