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Section: Eutectic calculation. The composition and temperature of a eutectic can be calculated from enthalpy and entropy of fusion of each components. The Gibbs free energy G depends on its own differential: G = H − T S ⇒ { H = G + T S ( ∂ G ∂ T ) P = − S ⇒ H = G − T ( ∂ G ∂ T ) P . {\displaystyle G=H-TS\Rightarrow {\b... | Wikipedia - Eutectic system - Eutectic calculation | 240 | 652 | null |
{\displaystyle G=H-TS\Rightarrow {\begin{cases}H=G+TS\\\left({\frac {\partial G}{\partial T}}\right)_{P}=-S\end{cases}}\Rightarrow H=G-T\left({\frac {\partial G}{\partial T}}\right)_{P}.} Thus, the G/T derivative at constant pressure is calculated by the following equation: ( ∂ G / T ∂ T ) P = 1 T ( ∂ G ∂ T ) P − 1 T 2... | Wikipedia - Eutectic system - Eutectic calculation | 371 | 808 | null |
{\displaystyle \left({\frac {\partial G/T}{\partial T}}\right)_{P}={\frac {1}{T}}\left({\frac {\partial G}{\partial T}}\right)_{P}-{\frac {1}{T^{2}}}G=-{\frac {1}{T^{2}}}\left(G-T\left({\frac {\partial G}{\partial T}}\right)_{P}\right)=-{\frac {H}{T^{2}}}.} The chemical potential μ i {\displaystyle \mu _{i}} is calcula... | Wikipedia - Eutectic system - Eutectic calculation | 354 | 720 | null |
{\displaystyle \mu _{i}=\mu _{i}^{\circ }+RT\ln {\frac {a_{i}}{a}}\approx \mu _{i}^{\circ }+RT\ln x_{i}.} At the equilibrium, μ i = 0 {\displaystyle \mu _{i}=0} , thus μ i ∘ {\displaystyle \mu _{i}^{\circ }} is obtained as μ i = μ i ∘ + R T ln x i = 0 ⇒ μ i ∘ = − R T ln x i . {\displaystyle \mu _{i}=\mu _{i}^{\circ... | Wikipedia - Eutectic system - Eutectic calculation | 247 | 482 | null |
{\displaystyle \mu _{i}=\mu _{i}^{\circ }+RT\ln x_{i}=0\Rightarrow \mu _{i}^{\circ }=-RT\ln x_{i}.} Using and integrating gives ( ∂ μ i / T ∂ T ) P = ∂ ∂ T ( R ln x i ) ⇒ R ln x i = − H i ∘ T + K . {\displaystyle \left({\frac {\partial \mu _{i}/T}{\partial T}}\right)_{P}={\frac {\partial }{\partial T}}\left(R\ln x_... | Wikipedia - Eutectic system - Eutectic calculation | 281 | 608 | null |
{\displaystyle \left({\frac {\partial \mu _{i}/T}{\partial T}}\right)_{P}={\frac {\partial }{\partial T}}\left(R\ln x_{i}\right)\Rightarrow R\ln x_{i}=-{\frac {H_{i}^{\circ }}{T}}+K.} The integration constant K may be determined for a pure component with a melting temperature T ∘ {\displaystyle T^{\circ }} and an entha... | Wikipedia - Eutectic system - Eutectic calculation | 283 | 661 | null |
{\displaystyle x_{i}=1\Rightarrow T=T_{i}^{\circ }\Rightarrow K={\frac {H_{i}^{\circ }}{T_{i}^{\circ }}}.} We obtain a relation that determines the molar fraction as a function of the temperature for each component: R ln x i = − H i ∘ T + H i ∘ T i ∘ . {\displaystyle R\ln x_{i}=-{\frac {H_{i}^{\circ }}{T}}+{\frac {H_... | Wikipedia - Eutectic system - Eutectic calculation | 218 | 471 | null |
{\displaystyle {\begin{cases}\ln x_{i}+{\frac {H_{i}^{\circ }}{RT}}-{\frac {H_{i}^{\circ }}{RT_{i}^{\circ }}}=0,\\\sum \limits _{i=1}^{n}x_{i}=1.\end{cases}}} { ∀ i < n ⇒ ln x i + H i ∘ R T − H i ∘ R T i ∘ = 0 , ln ( 1 − ∑ i = 1 n − 1 x i ) + H n ∘ R T − H n ∘ R T n ∘ = 0 , {\displaystyle {\begin{cases}\forall i<n\... | Wikipedia - Eutectic system - Eutectic calculation | 350 | 562 | null |
be solved by [ Δ x 1 Δ x 2 Δ x 3 ⋮ Δ x n − 1 Δ T ] = [ 1 / x 1 0 0 0 0 − H 1 ∘ R T 2 0 1 / x 2 0 0 0 − H 2 ∘ R T 2 0 0 1 / x 3 0 0 − H 3 ∘ R T 2 ⋮ ⋱ ⋱ ⋱ ⋱ ⋮ 0 0 0 0 1 / x n − 1 − H n − 1 ∘ R T 2 − 1 1 − ∑ i = 1 n − 1 x i − 1 1 − ∑ i = 1 n − 1 x i − 1 1 − ∑ i = 1 n − 1 x i − 1 1 − ∑ i = 1 n − 1 x i − 1 1 − ∑ i = 1 n − 1... | Wikipedia - Eutectic system - Eutectic calculation | 170 | 346 | null |
[ ln x 1 + H 1 ∘ R T − H 1 ∘ R T 1 ∘ ln x 2 + H 2 ∘ R T − H 2 ∘ R T 2 ∘ ln x 3 + H 3 ∘ R T − H 3 ∘ R T 3 ∘ ⋮ ln x n − 1 + H n − 1 ∘ R T − H n − 1 ∘ R T n − 1 ∘ ln ( 1 − ∑ i = 1 n − 1 x i ) + H n ∘ R T − H n ∘ R T n ∘ ] {\displaystyle {\begin{array}{c}\left[{\begin{array}{*{20}c}{\Delta x_{1}}\\{\Delta x_{2}}\... | Wikipedia - Eutectic system - Eutectic calculation | 346 | 560 | null |
{H_{3}^{\circ }}{RT^{2}}}}\\\vdots &\ddots &\ddots &\ddots &\ddots &{\vdots }\\0&0&0&0&{1/x_{n-1}}&{-{\frac {H_{n-1}^{\circ }}{RT^{2}}}}\\{\frac {-1}{1-\sum \limits _{i=1}^{n-1}{x_{i}}}}&{\frac {-1}{1-\sum \limits _{i=1}^{n-1}{x_{i}}}}&{\frac {-1}{1-\sum \limits _{i=1}^{n-1}{x_{i}}}}&{\frac {-1}{1-\sum \limits _{i=1}^{... | Wikipedia - Eutectic system - Eutectic calculation | 307 | 405 | null |
}}{RT^{2}}}}\\\end{array}}\right]^{-1}.\left[{\begin{array}{*{20}c}{\ln x_{1}+{\frac {H_{1}^{\circ }}{RT}}-{\frac {H_{1}^{\circ }}{RT_{1}^{\circ }}}}\\{\ln x_{2}+{\frac {H_{2}^{\circ }}{RT}}-{\frac {H_{2}^{\circ }}{RT_{2}^{\circ }}}}\\{\ln x_{3}+{\frac {H_{3}^{\circ }}{RT}}-{\frac {H_{3}^{\circ }}{RT_{3}^{\circ }}}}\\\... | Wikipedia - Eutectic system - Eutectic calculation | 336 | 446 | null |
Section: Utility of effect. A dipole can align to stabilize or destabilize the formation or loss of a charge, thereby decreasing (if stabilized) or increasing (if destabilized) the activation barrier to a chemical event. Field effects can therefore tune the acidity or basicity of bonds within their fields by donating o... | Wikipedia - Field effect (chemistry) - Utility of effect | 291 | 1,344 | null |
Section: Evidence for field effects. Localized electronic effects are a combination of inductive and field effects. Due to the similarity in these effects, it is difficult to separate their contributions to the electronic structure of a molecule. There is, however, a large body of literature devoted to developing an un... | Wikipedia - Field effect (chemistry) - Evidence for field effects | 318 | 1,491 | null |
Article: Forensic chemistry. Forensic chemistry is the application of chemistry and its subfield, forensic toxicology, in a legal setting. A forensic chemist can assist in the identification of unknown materials found at a crime scene. Specialists in this field have a wide array of methods and instruments to help ident... | Wikipedia - Forensic chemistry - Summary | 278 | 1,609 | null |
Section: Role in investigations. Forensic chemists' analysis can provide leads for investigators, and they can confirm or refute their suspicions. The identification of the various substances found at the scene can tell investigators what to look for during their search. During fire investigations, forensic chemists ca... | Wikipedia - Forensic chemistry - Role in investigations | 314 | 1,670 | null |
Section: History > Early history. Throughout history, a variety of poisons have been used to commit murder, including arsenic, nightshade, hemlock, strychnine, and curare. Until the early 19th century, there were no methods to accurately determine if a particular chemical was present, and poisoners were rarely punished... | Wikipedia - Forensic chemistry - History > Early history | 338 | 1,600 | null |
Stas's protocol was subsequently altered to incorporate tests for caffeine, quinine, morphine, strychnine, atropine, and opium. The wide range of instrumentation for forensic chemical analysis also began to be developed during this time period. The early 19th century saw the invention of the spectroscope by Joseph von ... | Wikipedia - Forensic chemistry - History > Early history | 231 | 1,205 | null |
Section: History > Modernization. Modern forensic chemists rely on numerous instruments to identify unknown materials found at a crime scene. The 20th century saw many advancements in technology that allowed chemists to detect smaller amounts of material more accurately. The first major advancement in this century came... | Wikipedia - Forensic chemistry - History > Modernization | 325 | 1,720 | null |
James and Archer John Porter Martin, allowing for the separation of volatile liquid mixtures with components which have similar boiling points. Nonvolatile liquid mixtures could be separated with liquid chromatography, but substances with similar retention times could not be resolved until the invention of high-perform... | Wikipedia - Forensic chemistry - History > Modernization | 242 | 1,231 | null |
Section: Methods > Spectroscopy. The two main standalone spectroscopy techniques for forensic chemistry are FTIR and AA spectroscopy. FTIR is a nondestructive process that uses infrared light to identify a substance. The attenuated total reflectance sampling technique eliminates the need for substances to be prepared b... | Wikipedia - Forensic chemistry - Methods > Spectroscopy | 313 | 1,653 | null |
AAS performs this analysis by subjecting the sample to an extremely high heat source, breaking the atomic bonds of the substance, leaving free atoms. Radiation in the form of light is then passed through the sample forcing the atoms to jump to a higher energy state.: 2 Forensic chemists can test for each element by usi... | Wikipedia - Forensic chemistry - Methods > Spectroscopy | 192 | 992 | null |
Section: Methods > Chromatography. Spectroscopy techniques are useful when the sample being tested is pure, or a very common mixture. When an unknown mixture is being analyzed it must be broken down into its individual parts. Chromatography techniques can be used to break apart mixtures into their components allowing f... | Wikipedia - Forensic chemistry - Methods > Chromatography | 329 | 1,648 | null |
This is useful in drug analysis where the pharmaceutical is a combination drug since the components would separate, or elute, at different times allowing for the verification of each component. The eluates from the HPLC column are then fed into various detectors that produce a peak on a graph relative to its concentrat... | Wikipedia - Forensic chemistry - Methods > Chromatography | 335 | 1,513 | null |
Section: Forensic toxicology. Forensic toxicology is the study of the pharmacodynamics, or what a substance does to the body, and pharmacokinetics, or what the body does to the substance. To accurately determine the effect a particular drug has on the human body, forensic toxicologists must be aware of various levels o... | Wikipedia - Forensic chemistry - Forensic toxicology | 346 | 1,764 | null |
Section: Standards. Guidelines have been set up by various governing bodies regarding the standards that are followed by practicing forensic scientists. For forensic chemists, the international Scientific Working Group for the Analysis of Seized Drugs (SWGDRUG) presents recommendations for the quality assurance and qua... | Wikipedia - Forensic chemistry - Standards | 341 | 1,829 | null |
Section: Standards > Testimony. The standardized procedures for testimony by forensic chemists are provided by the various agencies that employ the scientists as well as SWGDRUG. Forensic chemists are ethically bound to present testimony in a neutral manner and to be open to reconsidering their statements if new inform... | Wikipedia - Forensic chemistry - Standards > Testimony | 215 | 1,173 | null |
Section: 5-coordinate compounds. To distinguish whether the geometry of the coordination center is trigonal bipyramidal or square pyramidal, the τ5 (originally just τ) parameter was proposed by Addison et al.: τ 5 = β − α 60 ∘ ≈ − 0.01667 α + 0.01667 β {\displaystyle \tau _{5}={\frac {\beta -\alpha }{60^{\circ }}}\appr... | Wikipedia - Geometry index - 5-coordinate compounds | 172 | 572 | null |
Section: 4-coordinate compounds. In 2007 Houser et al. developed the analogous τ4 parameter to distinguish whether the geometry of the coordination center is square planar or tetrahedral. The formula is: τ 4 = 360 ∘ − ( α + β ) 360 ∘ − 2 θ ≈ − 0.00709 α − 0.00709 β + 2.55 {\displaystyle \tau _{4}={\frac {360^{\circ }-(... | Wikipedia - Geometry index - 4-coordinate compounds | 267 | 877 | null |
To overcome this issue, in 2015 Okuniewski et al. developed parameter τ4′ that adopts values similar to τ4 but better differentiates the examined structures: τ 4 ′ = β − α 360 ∘ − θ + 180 ∘ − β 180 ∘ − θ ≈ − 0.00399 α − 0.01019 β + 2.55 {\displaystyle \tau _{4}'={\frac {\beta -\alpha }{360^{\circ }-\theta }}+{\frac {18... | Wikipedia - Geometry index - 4-coordinate compounds | 298 | 941 | null |
Article: Gilchrist–Thomas process. The Gilchrist–Thomas process or Thomas process is a historical process for refining pig iron, derived from the Bessemer converter. It is named after its inventors who patented it in 1877: Percy Carlyle Gilchrist and his cousin Sidney Gilchrist Thomas. By allowing the exploitation of p... | Wikipedia - Gilchrist–Thomas process - Summary | 335 | 1,527 | null |
Section: A. absolute zero A theoretical condition concerning a system at the lowest limit of the thermodynamic temperature scale, or zero kelvins, at which the system does not emit or absorb energy (i.e. all atoms are at rest). By extrapolating the ideal gas law, the internationally agreed-upon value for absolute zero ... | Wikipedia - Glossary of chemistry terms - A | 331 | 1,503 | null |
(Brønsted–Lowry acid) Any chemical species or molecular entity that acts as a proton donor when reacting with another species, because it loses at least one proton (H+) which is then transferred or 'donated' to the other species, which by definition is a Brønsted–Lowry base. When dissolved in an aqueous solution, a pro... | Wikipedia - Glossary of chemistry terms - A | 331 | 1,493 | null |
3. Colloquially, any compound which, when dissolved in water, yields a pH of less than 7.0. The term "acid" is commonly used to refer to the entire aqueous solution, whereas stricter definitions refer only to the acidic solute. acid anhydride Any chemical compound derived by the removal of water molecules from an acid.... | Wikipedia - Glossary of chemistry terms - A | 337 | 1,672 | null |
adduct A distinct chemical species that is the sole product of an addition reaction between two other distinct reactant species, in which all of the atoms comprising the reactants are retained in the single product. Changes in connectivity may occur, but there is no loss of any of the original atoms and no gain of atom... | Wikipedia - Glossary of chemistry terms - A | 302 | 1,377 | null |
Aldehydes have the general formula R–C(H)=O. aliphatic alkali metal Any of the metallic elements belonging to Group 1 of the periodic table: lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr). alkaline alkaline earth metal Any of the metallic elements belonging to Group 2 of the pe... | Wikipedia - Glossary of chemistry terms - A | 350 | 1,343 | null |
alloy A mixture of metals or of a metal and another element which in combination exhibit a metallic bonding character. Common examples include bronze, brass, and pewter. amalgam Any alloy of mercury with another metal. ambident A molecule or functional group that has two alternative and interacting reaction sites, to e... | Wikipedia - Glossary of chemistry terms - A | 295 | 1,301 | null |
analyte The specific substance or chemical constituent that is of interest in a chemical analysis. analytical chemistry The branch of chemistry which studies and makes use of instruments and methods to separate, quantify, and identify chemical substances, both by classical wet chemistry techniques such as precipitation... | Wikipedia - Glossary of chemistry terms - A | 329 | 1,575 | null |
anode 1. An electrode through which the conventional electric current (the flow of positive charges) enters into a polarized electrical circuit. 2. The wire or plate of an electrochemical cell having an excess positive charge. Negatively charged anions always move toward the anode. Contrast cathode. anomer Either of a ... | Wikipedia - Glossary of chemistry terms - A | 315 | 1,360 | null |
Such rings are said to be aromatic. Arrhenius acid Any substance that, when dissolved in water, increases the concentration of H+ ions, or, more correctly, of hydronium ions (H3O+), in the resulting aqueous solution. The definition is similar to that of a Brønsted–Lowry acid. Contrast Arrhenius base. Arrhenius base Any... | Wikipedia - Glossary of chemistry terms - A | 341 | 1,538 | null |
It is identical to the charge number of the nucleus and is used in the periodic table to uniquely identify each chemical element. atomic orbital Any region in which one or more electrons may be found in an individual atom (as opposed to that within a molecule). atomic radius atomic weight See relative atomic mass. atom... | Wikipedia - Glossary of chemistry terms - A | 311 | 1,436 | null |
Section: B. balance backbone Also main chain. The primary or most structurally significant portion of a molecule with respect to its other parts, functional groups, moieties, or substituents; or, in the case of a polymer, that linear chain of atoms to which all other chains, long or short or both, may be regarded as be... | Wikipedia - Glossary of chemistry terms - B | 336 | 1,652 | null |
A model of the general structure of the atom proposed by Niels Bohr and Ernest Rutherford in 1913, featuring a small, dense nucleus of positively charged particles surrounded by orbiting electrons, which are attracted to the nucleus by electrostatic forces. This interpretation replaced several earlier hypotheses and qu... | Wikipedia - Glossary of chemistry terms - B | 332 | 1,747 | null |
Bonds are created as a result of a wide variety of electrochemical forces, whose strengths can vary considerably; they are broken when these forces are overcome by other forces. The types, strengths, and quantities of bonds holding together chemical substances dictate the structure and bulk properties of matter. bond a... | Wikipedia - Glossary of chemistry terms - B | 339 | 1,607 | null |
bung Also stopper or cork. A cylindrical or conical plug or closure used to seal a container such as a bottle, tube, flask, or barrel. burette Also spelled buret. Glassware used to dispense specific amounts of liquid when precision is necessary (e.g. during titrations and resource-dependent reactions). butyl The alkyl ... | Wikipedia - Glossary of chemistry terms - B | 214 | 897 | null |
Section: C. calorific value A measure of the heat per unit mass produced by complete combustion of a given substance, usually expressed in megajoules per kilogram (MJ/kg) or in kilojoules per gram (kJ/g). calorimeter Any of various devices used to measure thermal properties (i.e. heat), such as calorific values or heat... | Wikipedia - Glossary of chemistry terms - C | 349 | 1,505 | null |
Carbonyl groups are common to many classes of organic compounds and are also a part of many larger functional groups. 2. An inorganic or organometallic coordination complex with carbon monoxide as a ligand (e.g. a metal carbonyl). carboxyl carboxylic acid A class of organic acids and a functional group consisting of a ... | Wikipedia - Glossary of chemistry terms - C | 350 | 1,536 | null |
cathode An electrode from which the conventional electric current (the flow of positive charges) exits a polarized electrical circuit. Positively charged cations always move toward the cathode, though the cathode's polarity can be positive or negative depending on the type of electrical device and how it is being opera... | Wikipedia - Glossary of chemistry terms - C | 349 | 1,699 | null |
chelating agent chelation A type of bonding involving the formation of two separate coordinate covalent bonds between a polydentate ligand and a single central metal ion. The ligand is usually an organic compound called a chelant or chelating agent. chemical See chemical species and chemical compound. chemical bond See... | Wikipedia - Glossary of chemistry terms - C | 333 | 1,864 | null |
chemical reaction The change of one or more substances into one or more different substances. chemical species Also simply called a chemical. A chemical substance or ensemble of substances composed of chemically identical molecular entities which can explore the same set of molecular energy levels on a characteristic o... | Wikipedia - Glossary of chemistry terms - C | 305 | 1,666 | null |
Such a molecule or ion is said to be chiral, and exists in two forms, known as enantiomers, which are stereoisomers of each other; these forms are distinguished as either "right-handed" or "left-handed" by their absolute configuration or some other criterion. Several different types of asymmetry can give rise to chiral... | Wikipedia - Glossary of chemistry terms - C | 340 | 1,629 | null |
color standard A liquid solution of known chemical composition and concentration, and hence of known and standardized color, used as a reference in the optical analysis of samples of unknown strength. color test The quantitative analysis of a substance by comparing the intensity of the color produced when the substance... | Wikipedia - Glossary of chemistry terms - C | 346 | 1,842 | null |
the amount, in moles, of a dissolved solute per unit volume of a solution, a measure known as molar concentration or molarity. Several different definitions of concentration are widely used in chemistry, including molar concentration, mass concentration, and volume concentration. condensation The phase transition of a ... | Wikipedia - Glossary of chemistry terms - C | 337 | 1,624 | null |
constitutional unit An atom or group of atoms (including pendant atoms or groups, if any) comprising part of the structure of a macromolecule, oligomer, polymer, block, or chain. convection cooling curve A line graph representing the change between different phases of matter, typically from a gas to a solid or a liquid... | Wikipedia - Glossary of chemistry terms - C | 344 | 1,660 | null |
covalent bond Also molecular bond. A bond that involves the sharing of electron pairs between atoms. The stable balance of attractive and repulsive forces that occurs between atoms when they share electrons is known as covalent bonding. critical point The end point of a phase equilibrium curve or pressure-temperature c... | Wikipedia - Glossary of chemistry terms - C | 298 | 1,643 | null |
Section: D. dalton (Da) Also unified atomic mass unit (u). A unit of mass defined as 1⁄12 of the mass of a free unexcited atom of carbon-12 at rest. It is approximately equal to the mass of one nucleon. Dalton's law of partial pressures An empirical law which states that in a mixture of non-reacting gases, the total pr... | Wikipedia - Glossary of chemistry terms - D | 330 | 1,529 | null |
density An intensive property of a substance defined as mass per unit volume and expressed by the equation d = m/V. denticity The number of donor groups in a single ligand that bind to a central atom in a coordination complex. deposition The settling of particles within a solution or mixture. depression of freezing poi... | Wikipedia - Glossary of chemistry terms - D | 333 | 1,526 | null |
diatomic molecule Any molecule composed of only two atoms, of the same or different elements. diffusion The net movement of atoms or molecules from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in chemical potential of the diffusing species and depends on the ran... | Wikipedia - Glossary of chemistry terms - D | 320 | 1,625 | null |
dipole moment See electric dipole moment, magnetic dipole moment, molecular dipole moment, bond dipole moment, electron electric dipole moment, electron magnetic dipole moment, and nuclear magnetic moment. dispersion A system in which particles of one material are distributed within a continuous phase of another materi... | Wikipedia - Glossary of chemistry terms - D | 349 | 1,746 | null |
A salt composed of more than one different cation or anion, or which upon hydrolysis forms two different cations and anions. 2. A salt that is a molecular combination of two other salts. double-replacement reaction dropping point The temperature at which a grease changes from a semi-solid to a liquid state under standa... | Wikipedia - Glossary of chemistry terms - D | 253 | 1,276 | null |
Section: E. earth metal See alkaline earth metal. ebullition See boiling. effective molecular diameter The physical extent of the electron cloud surrounding a molecule of a particular gas, as calculated in any of several ways and usually expressed in nanometres or ångströms. effervescence The escape of gas from an aque... | Wikipedia - Glossary of chemistry terms - E | 314 | 1,487 | null |
For example, a battery contains one or more galvanic cells, each of which consists of two electrodes arranged such that an oxidation–reduction reaction produces an electromotive force. electrochemistry A branch of physical chemistry concerned with the relationship between electrical potential difference and identifiabl... | Wikipedia - Glossary of chemistry terms - E | 335 | 1,883 | null |
Knowledge of the specific arrangements of electrons in different atoms is useful for understanding chemical bonds and the organization of the periodic table of the elements. electron deficiency electron donor electron electric dipole moment (de) An intrinsic property of an electron such that its potential energy is lin... | Wikipedia - Glossary of chemistry terms - E | 321 | 1,662 | null |
The higher an atom or substituent's electronegativity, the more it attracts electrons towards itself. As it is usually calculated, electronegativity is not a property of an atom alone but rather of an atom within a molecule; it therefore varies with an element's chemical environment, though it is generally considered a... | Wikipedia - Glossary of chemistry terms - E | 303 | 1,548 | null |
Contrast stepwise reaction. elution The process of extracting one material from another by washing with a solvent. Elution works by running a solution containing an analyte past an adsorbent matrix designed to selectively bind the analyte molecules, and subsequently washing the adsorbent/analyte complex with a solvent,... | Wikipedia - Glossary of chemistry terms - E | 350 | 1,530 | null |
enthalpy of fusion entropy The amount of energy that is not available for work in a closed thermodynamic system, usually symbolized by S. environmental chemistry enzyme A biological protein catalyst that speeds up a chemical reaction. epimer Eppendorf tube A generalized and trademarked name used to refer to a microcent... | Wikipedia - Glossary of chemistry terms - E | 342 | 1,528 | null |
It is a common substituent in numerous organic compounds, though it may also exist independently as an ion or radical. In IUPAC nomenclature, the presence of an ethyl substituent may be indicated with the prefix ethyl in the name of the compound, or with the abbreviation Et in chemical formulae; e.g. ethyl alcohol (eth... | Wikipedia - Glossary of chemistry terms - E | 216 | 1,019 | null |
Section: F. family See group. Faraday constant (F) A unit of electric charge widely used in electrochemistry equal to the negative of the molar charge (electric charge per mole) of electrons. It is equal to approximately 96,500 coulombs per mole (F = 96485.33212... C/mol). Faraday's laws of electrolysis A set of two la... | Wikipedia - Glossary of chemistry terms - F | 326 | 1,613 | null |
first-order reaction flash point The lowest temperature at which the vapors above a volatile material will ignite if given an ignition source. At the flash point, the application of an open flame causes only a momentary "flash" rather than sustained combustion, for which the ambient temperature is still too low. The fl... | Wikipedia - Glossary of chemistry terms - F | 319 | 1,575 | null |
formal charge (FC) The electric charge assigned to an atom in a molecule, assuming that all electrons in all bonds are shared equally between atoms, regardless of each atom's relative electronegativity. The formal charge of any atom that is part of a molecule can be calculated by the equation F C = V − N − B 2 {\displa... | Wikipedia - Glossary of chemistry terms - F | 345 | 1,584 | null |
Common in industrial chemistry, the technique is sensitive enough to separate compounds which have boiling points that differ by less than 25 °C (45 °F) from each other at standard pressure. fractionation A separation process in which a particular quantity of a mixture is divided during a phase transition into a number... | Wikipedia - Glossary of chemistry terms - F | 285 | 1,482 | null |
Section: G. galvanic cell A type of battery made up of electrochemicals with two different metals connected by a salt bridge. gas One of the four fundamental states of matter, characterized by high-energy particles which fill their container but have no definite shape or volume. gas chromatography A type of chromatogra... | Wikipedia - Glossary of chemistry terms - G | 326 | 1,501 | null |
Section: H. hadron A subatomic particle of a type including the baryons and mesons that can take part in the strong interaction. halogen Any of the five non-metallic elements of Group 17 of the periodic table: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). hard acid A Lewis acid with an elect... | Wikipedia - Glossary of chemistry terms - H | 317 | 1,469 | null |
hydration reaction hydride hydrocarbon hydrogen hydrogen bond A form of electrostatic interaction between an electronegative atom and a hydrogen atom bound to a second electronegative atom. Hydrogen bonding is unique because the small size of the hydrogen atoms permits proximity of the interacting electrical charges, a... | Wikipedia - Glossary of chemistry terms - H | 321 | 1,496 | null |
Section: I. ideal gas A hypothetical gas composed of many randomly moving point particles that do not participate in any interparticle interactions, thereby making it mathematically convenient to describe and predict their behavior as state variables change. The ideal gas concept is useful because it obeys the ideal ga... | Wikipedia - Glossary of chemistry terms - I | 340 | 1,675 | null |
induced radioactivity Radioactivity caused by bombarding a stable isotope with elementary particles, forming an unstable, radioactive isotope. inert (of a chemical species) Stable and chemically unreactive; or thermodynamically non-labile, decomposing at a slow or negligible rate. Examples of inert species include the ... | Wikipedia - Glossary of chemistry terms - I | 343 | 1,820 | null |
Intermetallics are generally hard and brittle, and have useful mechanical properties at high temperatures. intermolecular force Any force that mediates interaction between molecules, e.g. electromagnetic forces of attraction or repulsion, hydrogen bonding, and the van der Waals force, all of which act between the atoms... | Wikipedia - Glossary of chemistry terms - I | 349 | 1,768 | null |
Section: K. kelvin (K) The SI unit of temperature (symbol: K). The Kelvin scale is an absolute thermodynamic temperature scale that uses absolute zero as its null point. keto acid Also ketoacid. Any organic compound that can be classified as both a ketone and a carboxylic acid, by virtue of containing a keto group and ... | Wikipedia - Glossary of chemistry terms - K | 168 | 722 | null |
Section: L. lability lanthanides Also lanthanoids. The periodic series of metallic elements with atomic numbers 57 through 71, from lanthanum through lutetium. lattice The unique geometric arrangement of atoms or molecules in a crystalline liquid or solid. lattice energy The energy released upon the formation of one mo... | Wikipedia - Glossary of chemistry terms - L | 324 | 1,622 | null |
Section: M. macromolecule A very large molecule comprising many atoms and bonds, or any molecule with a high relative molecular mass, especially one whose structure is formed by the multiple repetition of discrete subunits derived, actually or conceptually, from molecules with low relative molecular mass (e.g. monomers... | Wikipedia - Glossary of chemistry terms - M | 303 | 1,476 | null |
Mass number varies between different isotopes of the same chemical element, and is often included either after the element's name (as in carbon-12) or as a superscript to the left of the element's symbol (as in 12C) to identify a specific isotope. mass spectrometry (MS) An analytical technique that measures the mass-to... | Wikipedia - Glossary of chemistry terms - M | 325 | 1,578 | null |
metalloid A chemical element or substance possessing properties of both metals and non-metals. metamer See isomer. metathesis A class of chemical reaction involving the exchange of elements or functional groups between two or more compounds, as described by the general equation A X + B Y → A Y + B X {\textstyle \mathrm... | Wikipedia - Glossary of chemistry terms - M | 334 | 1,450 | null |
mineral A solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form. miscibility The tendency or capability of two or more substances to blend uniformly when combined (most commonly liquids, though the concept is also applicable to solids... | Wikipedia - Glossary of chemistry terms - M | 320 | 1,578 | null |
molar attenuation coefficient molar concentration Also molarity, amount concentration, or substance concentration. A measure of the concentration of a chemical species, especially of a solute in a solution, in terms of the amount of the species per unit volume of solution. Molarity is typically expressed in units of mo... | Wikipedia - Glossary of chemistry terms - M | 348 | 1,610 | null |
Section: N. natural abundance neat Conditions with a liquid reagent or gas performed with no added solvent or cosolvent. neutron A type of subatomic particle that is electrically neutral, having no net charge. nitrogen noble gas Also inert gas. Any of the six non-metallic elements of Group 18 of the periodic table: hel... | Wikipedia - Glossary of chemistry terms - N | 288 | 1,389 | null |
nucleophile Any atom or molecule which can donate an electron pair to another atom or molecule. All molecules or ions with a free pair of electrons or at least one pi bond can act as nucleophiles, by which they are attracted to electron-deficient regions of other species; a chemical reaction involving a nucleophile don... | Wikipedia - Glossary of chemistry terms - N | 199 | 908 | null |
Section: O. octet rule Also Lewis octet rule. A classical rule for describing the electron configuration of atoms in certain molecules: the maximum number of electron pairs that can be accommodated in the valence shell of an element in the first row of the periodic table is four (or eight total electrons). For elements... | Wikipedia - Glossary of chemistry terms - O | 323 | 1,676 | null |
from the more dilute solution to the more concentrated solution, or, equivalently, from a region of high water potential to a region of low water potential. Because the solute is unable to cross the membrane, the tendency towards equilibration compels the solvent to cross the membrane instead. This continues until an e... | Wikipedia - Glossary of chemistry terms - O | 337 | 1,637 | null |
Section: P. p-block paired electron One of two electrons that together form a valence bond between two atoms. Contrast unpaired electron. paraffin 1. A trivial (non-IUPAC) name for any alkane. 2. Another name for kerosene. partial pressure partition coefficient pascal (Pa) passivation The process of coating a substance... | Wikipedia - Glossary of chemistry terms - P | 328 | 1,452 | null |
per- A prefix in IUPAC chemical nomenclature meaning complete, exhaustive, or extreme, as in a completely substituted hydrocarbon; or indicating the presence of a peroxy group. peracid An acid containing an acidic peroxy group (–O–O–); e.g. periodic acid. period A horizontal row of the periodic table of the elements an... | Wikipedia - Glossary of chemistry terms - P | 338 | 1,497 | null |
pH A logarithmic scale used to specify the acidity or basicity of an aqueous solution. The pH scale approximates the negative of the base-10 logarithm of the molar concentration of hydrogen ions in a solution. At room temperature, pure water is neutral (pH = 7); solutions with a pH less than 7 are acidic and those with... | Wikipedia - Glossary of chemistry terms - P | 333 | 1,582 | null |
phi bond photon A carrier of electromagnetic radiation of all wavelengths (such as gamma rays and radio waves). physical chemistry The branch of chemistry that studies chemical systems in terms of the principles, practices, and concepts of physics, such as motion, energy, force, time, thermodynamics, chemical equilibri... | Wikipedia - Glossary of chemistry terms - P | 327 | 1,547 | null |
Contrast monatomic and diatomic. polyatomic ion A molecule composed of two or more covalently bonded atoms which collectively bear a net electric charge and therefore act as an ion. polymerization The chemical bonding of two or more individual monomer molecules to form a polymer chain or network; or any reaction that p... | Wikipedia - Glossary of chemistry terms - P | 338 | 1,605 | null |
Compare accuracy. pressure The force applied perpendicular to the surface of an object per unit area. The SI unit for pressure is the pascal (Pa), though many other units of pressure are also commonly used in chemistry. primary The simplest, most commonly known, or canonical form of a chemical compound with multiple si... | Wikipedia - Glossary of chemistry terms - P | 339 | 1,368 | null |
protective group protic Also protogenic. (of a chemical species) Capable of acting as a proton donor; readily generating or yielding free protons (H+) in solution. Protic species may therefore be considered strongly or weakly acidic in the sense of a Brønsted–Lowry acid. proton A subatomic particle with a positive elec... | Wikipedia - Glossary of chemistry terms - P | 154 | 715 | null |
Section: R. racemate An equimolar mixture of a pair of enantiomers which does not exhibit optical activity. The chemical name or formula of a racemate is distinguished from those of the enantiomers by the prefix (±)- or by the symbols RS and SR. radiation Energy released in the form of waves or subatomic particles when... | Wikipedia - Glossary of chemistry terms - R | 342 | 1,668 | null |
rare-earth element Also called rare-earth metals or used interchangeably with lanthanides. Any of the 17 nearly indistinguishable, silvery-white, soft, heavy metallic elements belonging to a set including the lanthanide series (atomic numbers 57 through 71) as well as scandium and yttrium. rate equation Also rate law. ... | Wikipedia - Glossary of chemistry terms - R | 342 | 1,756 | null |
reaction rate The speed at which reactants are converted into products in a chemical reaction. reaction rate constant reactive bond A chemical bond between atoms which, in a particular context, is relatively unstable and therefore easily broken or invaded by other chemical species or radicals; e.g. the double bond in e... | Wikipedia - Glossary of chemistry terms - R | 313 | 1,638 | null |
Chemical stability and chemical compatibility are related but distinct concepts. reactivity series Also activity series. An empirical, calculated, and structurally analytical progression of a series of metals, arranged by their general reactivity from highest to lowest and used to summarize information about their reac... | Wikipedia - Glossary of chemistry terms - R | 300 | 1,475 | null |
Section: S. s-block The collective name for the elements in Groups 1 and 2 of the periodic table (the alkali and alkaline metals), as well as hydrogen and helium. saline solution A common term for a solution of sodium chloride (NaCl) dissolved in water (H2O). salt Any ionic compound composed of one or more anions and o... | Wikipedia - Glossary of chemistry terms - S | 314 | 1,560 | null |
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