Glossary of chemical terms

Fahrenheit scale
	Fahrenheit scale is the temperature scale in which 212 degrees is the boiling point of water and 32 degrees is the freezing point of water. The scale was invented in 1714 by a German physicist G.D. Fahrenheit (1686-1736). 32°F = 0°C 212°F = 100°C 1°F =(5/9)°C T(°C) = (5/9)[T(°F) - 32] T(°F) = (9/5)T(°C) + 32
farad
	Farad (F) is the SI derived unit of electric capacitance. The farad is the capacitance of an electric capacitor between the two plates of which there appears a difference of electric potential of one volt when it is charged by a quantity of electricity equal to one coulomb (F = C/V). The unit is named after the British scientist M. Faraday (1791-1867).
Faraday constant
	Faraday constant (F) is the electric charge of 1 mol of singly charged positive ions. F = NA × e = 96487 C mol-1 where NA is Avogadro's constant (6.022 × 1023 mol-1) and e is the elementary charge (1.602 × 10-19 C).
fatty acids
	Fatty acids are aliphatic monocarboxylic acids characterized by a terminal carboxyl group (R-COOH). Natural fatty acids commonly have a chain of 4 to 28 carbons (usually unbranched and even-numbered), which may be saturated or unsaturated. The most important of saturated fatty acids are butyric (C4), lauric (C12), palmitic (C16), and stearic (C18). The most common unsaturated acids are oleic, linoleic, and linolenic (all C18). The physical properties of fatty acids are determined by chain length, degree of unsaturation, and chain branching. Short-chain acids are pungent liquids, soluble in water. As chain length increases, melting points are raised and water-solubility decreases. Unsaturation and chain branching tend to lower melting points.
Fermi level
	Fermi level is the highest energy of occupied states in a solid at zero temperature. The Fermi level in conductors lies in the conduction band, in insulators it lies in the valence band, and in semiconductors it falls in the gap between the conduction band and the valence band. It is named after the Italian physicst Enrico Fermi (1901 - 1954).
fermion
	Fermion is any particle with spin equal to an odd multiple of 1/2. Fermion is a particle that obeys Fermi-Dirac statistics, e.g. electron, proton, neutron, muon, etc.
ferrites
	Ferrites are ceramic materials of nominal formula MO.Fe2O3, where M is a divalent metal (Co, Mn, NI, or Zn). The ferrites show either ferrimagnetism or ferromagnetism, but are not electrical conductors, and they are used in high-frequency circuits as magnetic cores, in rectifiers on memory and record tapes, and various related uses in radio, television, radar, computers, and automatic control systems.
ferromagnetism
	Ferromagnetism is a type of magnetism in which the magnetic moments of atoms in a solid are aligned within domains which can in turn be aligned with each other by a weak magnetic field. The total magnetic moment of a sample of the substance is the vector sum of the magnetic moments of the component domains. In an unmagnetized piece of ferromagnetic material the magnetic moments of the domains themselves are not aligned; when an external field is applied those domains that are aligned with the field increase in size at the expense of the others. Ferromagnetic materials can retain their magnetization when the external field is removed, as long as the temperature is below a critical value, the Curie temperature. They are characterized by a large positive magnetic susceptibility.
Fick's law
	Fick's law is the statement that the flux J of a diffusing substance is proportional to the concentration gradient, i.e., J = -D(dc/dx) where D is called the diffusion coefficient.
flash point
	Flash point is the lowest temperature at which a liquid or volatile solid gives off vapour sufficient to form an ignitable mixture with the air near the surface of the liquid or within the test vessel (NFPA).
foam
	Foams are dispersions of gases in liquids or solids. The gas globule may be of any size, from colloidal to macroscopic, as in soap bubbles. Bakers' bread and sponge rubber are examples of solid foams. Typical liquid foams are those used in fire-fighting, shaving creams, etc. Foams made by mechanical incorporation of air are widely used in the food industry (e.g. whipped cream, egg white, ice cream, etc.). Foams can be stabilized by surfactants.
free radical
	Free radical is a molecular fragment having one or more unpaired electrons, usually short-lived and highly reactive. They can be produced by photolysis or pyrolysis in which a bond is broken without forming ions. In formulas, a free radical is conventionally indicated by a dot (Cl∙). Free radicals are known to be formed by ionising radiation and thus play a part in deleterious degradation effects that occur in irradiated tissue. They also act as initiators or intermediates in oxidation, combustion, photolysis, and polymerisation.
free radical
	Free radical is highly reactive molecule or atom with an unpaired electron. The species is often represented by a formula with a single dot as the unpaired electron (∙CH3, ∙SnH3, ∙Cl).
freezing point
	See Melting point
frequency
	Frequency (ν) is number of cycles of a periodic phenomenon divided by time. Hertz (Hz) is the SI derived unit, with a special name, for frequency, equal to s-1. It is named after the German scientist Heinrich Hertza (1857-1894).
Froude number
	Froude number (Fr) is a dimensionless quantity used in fluid mechanics, defined by where v is velocity, l is length, and g is acceleration due to gravity.
fugacity
	Fugacity (f) is a thermodynamic function used in place of partial pressure in reactions involving real gases and mixtures. For a component of a mixture, it is defined by dμ = RT(lnf) where μ is the chemical potential. The fugacity of a gas is equal to the pressure if the gas is ideal. The fugacity of a liquid or solid is the fugacity of the vapour with which it is in equilibrium. The ratio of the fugacity to the fugacity in some standard state is the activity.

 

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