In chemical physics and physical chemistry, chemical affinity can be defined as electronic properties by which dissimilar chemical species are capable of forming chemical compounds. Chemical physics is a subdiscipline of Chemistry and Physics that investigates physicochemical phenomena using techniques from atomic and molecular physics Physical chemistry, is the application of Physics to macroscopic microscopic atomic subatomic and particulate phenomena in chemical systems It is mostly defined as a large Chemical species are Atoms Molecules molecular fragments Ions etc A chemical compound is a substance consisting of two or more different elements chemically bonded together in a fixed proportion by Mass. ^[1] Chemical affinity can also refer to the tendency of an atom or compound to combine by chemical reaction with atoms or compounds of unlike composition. History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called

According to chemistry historian Henry Leicester, the influential 1923 textbook Thermodynamics and the Free Energy of Chemical Reactions by Gilbert N. Lewis and Merle Randall led to the replacement of the term “affinity” by the term “free energy” in much of the English-speaking world. Gilbert Newton Lewis ( October 23, 1875 - March 23, 1946) was a famous American physical chemist known for the discovery Merle Randall (1888-1950 was an American Physical chemist famous for his work over the period of 25 years in measuring free energy calculations of compounds with In Thermodynamics, the term thermodynamic free energy refers to the amount of work that can be extracted from a System, and is helpful in Engineering

Modern conceptions

In modern terms, we relate affinity to the phenomenon whereby certain atoms or molecules have the tendency to aggregate or bond. For example, in the 1919 book Chemistry of Human Life physician George W. Carey states: “Health depends on a proper amount of iron phosphate Fe₃(PO₄)₂ in the blood, for the molecules of this salt have chemical affinity for oxygen and carry it to all parts of the organism. ” In this antiquated context, chemical affinity is sometimes found synonymous with the term "magnetic attraction". Many writings, up until about 1925, also refer to a “law of chemical affinity”.

Thermodynamics

In 1923, the Belgian mathematician and physicist Théophile de Donder derived a relation between affinity and the Gibbs free energy of a chemical reaction. Théophile Ernest de Donder (1872 – 1957 was a Belgian mathematician and physicist famous for his 1923 work in developing correlations between the Newtonian concept of In Thermodynamics, the Gibbs free energy ( IUPAC recommended name Gibbs energy or Gibbs function) is a Thermodynamic potential which A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called Through a series of derivations, de Donder showed that if we consider a mixture of chemical species with the possibility of chemical reaction, it can be proved that the following relation holds:

With the writings of Théophile de Donder as precedent, Ilya Prigogine and Defay in Chemical Thermodynamics (1954) defined chemical affinity (denoted by ) as a function of the increments in uncompensated heat of reaction and reaction progress variable (denoted by and , respectively):

. Chemical species are Atoms Molecules molecular fragments Ions etc Théophile Ernest de Donder (1872 – 1957 was a Belgian mathematician and physicist famous for his 1923 work in developing correlations between the Newtonian concept of Ilya Viscount Prigogine (Илья́ Рома́нович Приго́жин ( January 25, 1917 &ndash May 28, 2003) was a Russian       (1).

This definition is useful for quantifying the factors responsible both for the state of equilibrium systems (where ), and for changes of state of non-equilibrium systems (where ).

The present IUPAC definition of chemical affinity is: Negative partial derivative of Gibbs energy with respect to extent of reaction at constant pressure and temperature. The International Union of Pure and Applied Chemistry ( IUPAC) (aɪjuːpæk or ay-yoo-pec) is an international Non-governmental organization It is positive for spontaneous reactions. ^[2]

History

"Chemical affinity", historically, refers to the "force" that causes chemical reactions. In Physics, the electromagnetic force is the force that the Electromagnetic field exerts on electrically charged particles A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called ^[3] A broad definition, used generally throughout history, is that chemical affinity is that whereby substances enter into or resist decomposition. ^[4] In current use, it

The following statement, made by Ilya Prigogine, summarizes the concept of affinity:

The term affinity has been used figuratively since c. Ilya Viscount Prigogine (Илья́ Рома́нович Приго́жин ( January 25, 1917 &ndash May 28, 2003) was a Russian In a Chemical process, chemical equilibrium is the state in which the chemical activities or Concentrations of the reactants and products have no net change 1600 in discussions of structural relationships in chemistry, philology, etc. See Comparative linguistics for the narrower field of "comparative philology" , and reference to "natural attraction" is from 1616.

The idea of affinity is extremely old. Many attempts have been made at identifying its origins. ^[4] The majority of such attempts, however, except in a general manner, end in futility since ‘affinities’ lie at the basis of all magic, thereby pre-dating science. Magic, sometimes known as sorcery, is a Conceptual system that asserts human ability to control the natural world (including events objects people and Science (from the Latin scientia, meaning " Knowledge " or "knowing" is the effort to discover, and increase human understanding ^[5] Physical chemistry, however, was one of the first branches of science to study and formulate a "theory of affinity". Physical chemistry, is the application of Physics to macroscopic microscopic atomic subatomic and particulate phenomena in chemical systems It is mostly defined as a large The name affinitas was first used in the sense of chemical relation by German philosopher Albertus Magnus near the year 1250. Later, those as Robert Boyle, John Mayow, Johann Glauber, Isaac Newton, and Georg Stahl put forward ideas on elective affinity in attempts to explain how heat is evolved during combustion reactions. Robert Boyle was a Natural philosopher, chemist physicist inventor and early Gentleman scientist, noted for his work in Physics and Chemistry John Mayow FRS (1641 - 1679 was a Chemist, Physician, and Physiologist who is remembered today for conducting early research into respiration Johann Rudolf Glauber ( 1604 (? March 10 1670) a German - Dutch alchemist and Chemist. Sir Isaac Newton, FRS (ˈnjuːtən 4 January 1643 31 March 1727) Biography Early years See also Isaac Newton's early life and achievements Georg Ernst Stahl ( October 21, 1660 &ndash May 24, 1734) was a German Chemist and Physician. In Physics, heat, symbolized by Q, is Energy transferred from one body or system to another due to a difference in Temperature Combustion or burning is a complex sequence of Exothermic chemical reactions between a Fuel and an Oxidant accompanied by the production of ^[6]

The modern term chemical affinity is a somewhat modified variation of its eighteenth-century precursor "elective affinity" or elective attractions, a coinage of the Swedish chemist Torbern Olof Bergman from his book De attractionibus electivis (1775). Torbern Olof Bergman ( March 20, 1735 Katrineberg, Sweden, &ndash July 8, 1784 Medevi, Sweden) was Antoine Lavoisier, in his famed 1790 Elements of Chemistry, refers to Bergmann’s work and discusses the concept of elective affinities or attractions.

Goethe used the concept in his novel Elective Affinities, (1809)

Geoffroy's 1718 affinity table

The first-ever affinity table, which was based on displacement reactions, was published in 1718 by the French chemist Étienne François Geoffroy. ˈjoːhan ˈvɔlfgaŋ fɔn ˈgøːtə (in English generally ˈgɝːtə 28 August 1749 22 March 1832 was a German writer Elective Affinities (Die Wahlverwandtschaften is the third novel by Johann Wolfgang von Goethe, published in 1809 A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called Étienne François Geoffroy ( February 13, 1672 - January 6, 1731) French Physician and Chemist, best known Geoffroy's name is best known in connection with these tables of "affinities" (tables des rapports), which were first presented to the French Academy in 1718 and 1720, as shown below:

Geoffroy's Affinity Table (1718): At the head of the column is a substance with which all the substances below can combine, where each column below the header is ranked by degrees of "affinity". L'Académie française, or the French Academy, is the pre-eminent French learned body on matters pertaining to the French language. Year 1718 ( MDCCXVIII) was a Common year starting on Saturday (link will display the full calendar of the Gregorian calendar (or a

These were lists, prepared by collating observations on the actions of substances one upon another, showing the varying degrees of affinity exhibited by analogous bodies for different reagents, and they retained their vogue for the rest of the century, until displaced by the profounder conceptions introduced by Claude Berthollet. A reagent or reactant is a substance or compound consumed during a Chemical reaction. Claude Louis Berthollet ( December 9, 1748 &ndash November 6, 1822) was a Savoyard Chemist who "became vice president

See also

• Chemistry
• Chemical reaction
• Chemical bond
• Electronegativity
• Electron affinity
• Étienne François Geoffroy - Geoffroy's 1718 Affinity Table
• Valency

References

1. ^ Chemical Affinity - Britannica 1911
2. ^ IUPAC Green Book and Gold Book in .pdf
3. ^ Thomas Thomson. Chemistry (from Egyptian kēme (chem meaning "earth") is the Science concerned with the composition structure and properties A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called A chemical bond is the physical process responsible for the attractive interactions between Atoms and Molecules and which confers stability to diatomic and polyatomic " Electronegativity " is the opposite of " Electropositivity," which describes an element's ability to donate electrons The electron affinity, E ea of an Atom or Molecule is the energy required to detach an electron from a singly charged negative Étienne François Geoffroy ( February 13, 1672 - January 6, 1731) French Physician and Chemist, best known In Chemistry, valence, also known as valency or valency number, is a measure of the number of Chemical bonds formed by the Atoms Thomas Thomson FRS ( 12 April, 1773 &ndash 2 July, 1852) was a Scottish Chemist whose writings contributed (1831). A System of Chemistry, vol. 1. p. 31 (chemical affinity is described as an "unknown force"). 7th ed. , 2 vols.
4. ^ ^{a b} Levere, Trevor, H. (1971). Affinity and Matter – Elements of Chemical Philosophy 1800-1865. Gordon and Breach Science Publishers. ISBN 2881245838.  
5. ^ Malthauf, R. P. (1966). The Origins of Chemistry. Pg. 299. London.
6. ^ Partington, J. R. (1937). A Short History of Chemistry. New York: Dover Publications, Inc. ISBN 0-486-65977-1

Further reading

Important books on Newton's alchemy, as he was one of the main proponents of the theory of chemical affinity, are:

1. Dobbs, Betty Jo Teeter. The Foundations of Newton's Alchemy: or, "The Hunting of the Greene Lyon". Cambridge: Cambridge University Press, 1975. ISBN 0-521-20786-X
2. Dobbs, Betty Jo Teeter. The Janus Faces of Genius: the Role of Alchemy in Newton's Thought. Cambridge: Cambridge University Press, 1991. ISBN 0-521-38084-7

Notes

• The excerpt from Janus Faces at [1] includes a discussion of the historiographical issue of Newton's alchemy and footnotes that provide a starting bibliography on Newton's alchemy.
• This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain. The Encyclopædia Britannica Eleventh Edition (1910–1911 is a 29-volume reference work that marked the beginning of the Encyclopædia Britannica The public domain is a range of abstract materials &ndash commonly referred to as Intellectual property &ndash which are not owned or controlled by anyone

External links

• Chemical Affinity and Absolute Zero - 1920 Nobel Prize in Chemistry Presentation Speech by Gerard de Geer
• Elements, Principles and the Narrative of Affinity – Essay Review