JonyC/ScienceGlossary · Datasets at Hugging Face

term stringlengths 1 63 ⌀	category stringclasses 15 values	label int64 0 1	definition stringlengths 5 3.18k ⌀
ethyl	Chemistry	1	The alkyl functional group derived from ethane, consisting of two carbon atoms covalently bonded to each other and fully saturated with bonds to hydrogen atoms, with the chemical formula –CH2CH3. 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 (ethanol), which is often written with the formula CH3CH2OH or EtOH.
eutectic mixture	Chemistry	1	A solid solution consisting of two or more substances which collectively have the lowest melting point of any possible mixture of these components.
extensive property	Chemistry	1	A physical quantity whose value is proportional to the size of the system it describes or to the quantity of matter in the system. Examples include mass, volume, enthalpy, and entropy. Contrast intensive property.
extraction	Chemistry	1	1. A separation process in which a component is separated from its mixture by selective solubility. See also partition.
family	Chemistry	1	See group.
faraday constant	Chemistry	1	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).
f	Chemistry	1	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	Chemistry	1	A set of two laws pertaining to electrolysis which hold that: a) the mass of a substance altered at an electrode during electrolysis is directly proportional to the quantity of electricity transferred at that electrode; and b) the mass of an elemental material altered at an electrode is directly proportional to the element's equivalent weight.
filtration	Chemistry	1	Any physical, biological, or chemical operation that separates large particles (often solid matter) from smaller particles (often a fluid) by passing the mixture through a complex lattice structure through which only particles of a sufficiently small size can pass, called a filter. The fluid and small particles which successfully pass through the filter are called the filtrate.
fire point	Chemistry	1	The lowest temperature at which the vapors above a volatile material will continue to burn for at least five seconds after ignition by an open flame of standard dimension. The fire point should not be confused with the flash point, a slightly lower temperature at which a substance will ignite briefly but at which vapor is not produced at a rate sufficient for sustained combustion.
flash point	Chemistry	1	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 flash point should not be confused with the fire point, which occurs at a slightly higher temperature, nor with the kindling point, which is higher still.
flask	Chemistry	1	A vessel or container, most commonly a type of glassware, widely used in laboratories for a variety of purposes, such as preparing, holding, containing, collecting, and volumetrically measuring chemicals, samples, or solutions, or as a chamber in which a chemical reaction occurs. Flasks come in a number of shapes and sizes but are typically characterized by a relatively wide lower body which tapers into one or more narrower tubular sections with an opening at the top.
flocculation	Chemistry	1	The process by which the dispersed particles in a colloid come out of suspension to aggregate into larger clumps known as floc or flake, either spontaneously or due to the addition of a clarifying agent. The term is often used to refer to a reversible aggregation in which the forces holding the particles together are weak and the colloid can be re-dispersed by agitation.
florence flask	Chemistry	1	See boiling flask.
formal charge	Chemistry	1	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 FC=V-N-{\frac {B}{2}}\ } , where V V} is the number of valence electrons of the neutral atom in its ground state; N N} is the number of valence electrons of the atom which are not participating in bonds in the molecule; and B B} is the number of electrons shared in bonds with other atoms in the molecule.
fc	Chemistry	1	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 FC=V-N-{\frac {B}{2}}\ } , where V V} is the number of valence electrons of the neutral atom in its ground state; N N} is the number of valence electrons of the atom which are not participating in bonds in the molecule; and B B} is the number of electrons shared in bonds with other atoms in the molecule.
formula weight	Chemistry	1	A synonym for molar mass and molecular weight, frequently used for non-molecular compounds such as ionic salts.
fw	Chemistry	1	A synonym for molar mass and molecular weight, frequently used for non-molecular compounds such as ionic salts.
fractional distillation	Chemistry	1	When a mixture containing at least one part liquid is separated into its component parts, or fractions, such as in separating chemical compounds by their boiling point by heating them to a temperature at which several fractions of the compound will evaporate (for example, the refining of crude oil).
fractionation	Chemistry	1	A separation process in which a particular quantity of a mixture is divided during a phase transition into a number of smaller quantities, known as fractions, for which the chemical composition varies according to a gradient. Fractionation exploits subtle differences in some specific property (e.g. mass, boiling point, solubility, etc.) between the mixture's component compounds, making it possible to isolate more than two components of a mixture at the same time. There are many varieties of fractionation employed in many branches of science and technology.
free radical	Chemistry	1	See radical.
freeze-drying	Chemistry	1	See lyophilization.
freezing	Chemistry	1	The phase transition of a substance from a liquid to a solid.
freezing point	Chemistry	1	The temperature at which a substance changes state from a liquid to a solid. Because freezing is the reverse of melting, the freezing point of a substance is identical to its melting point, but by convention only the melting point is referred to as a characteristic property of a substance.
frequency	Chemistry	1	A measurement of the number of cycles of a given process per unit of time. The SI unit for measuring frequency is the hertz (Hz), with 1 Hz = 1 cycle per second.
galvanic cell	Chemistry	1	A type of battery made up of electrochemicals with two different metals connected by a salt bridge.
gas	Chemistry	1	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	Chemistry	1	A type of chromatography commonly used in analytical chemistry to isolate and analyze chemical compounds that can be vaporized without decomposition. Gas chromatography is often used to test the purity of substances, to identify unknown substances, and to measure the relative amounts of the different components of mixtures.
gauche	Chemistry	1	In alkane stereochemistry, a structural conformation involving a torsion angle of ±60°, or a synclinal alignment of functional groups attached to adjacent atoms.
gay-lussac's law	Chemistry	1	A chemical law used for each of the two relationships derived by French chemist Joseph Louis Gay-Lussac and which concern the properties of gases, though the name is more usually applied to his law of combining volumes.
geochemistry	Chemistry	1	The study of the chemistry and chemical composition of the Earth and geological processes.
gibbs energy	Chemistry	1	A value that indicates the spontaneity of a reaction. Usually symbolized as G.
glycol	Chemistry	1	Any of a class of aliphatic dihydric alcohols in which the two hydroxy groups are bonded to two different carbon atoms, which are usually but not necessarily adjacent to each other; e.g. ethylene glycol (HOCH2CH2OH).
gram-atom	Chemistry	1	A former term for a mole.
ground glass joint	Chemistry	1	An apparatus designed to quickly and easily fit two pieces of leak-tight glassware together, featuring ground glass surfaces and typically a custom-made conical taper.
ground state	Chemistry	1	The lowest possible energy state for a given quantum mechanical system, at which the Gibbs energy is actually or theoretically minimized. Whatever energy remains in the system in its ground state is called the zero-point energy. Contrast excited state.
group	Chemistry	1	A vertical column of the periodic table of the elements and the elements that share it. Contrast period.
hadron	Chemistry	1	A subatomic particle of a type including the baryons and mesons that can take part in the strong interaction.
halogen	Chemistry	1	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	Chemistry	1	A Lewis acid with an electron-accepting centre that is only weakly polarizable. Hard acid species also tend to have high charge states and relatively small atomic nuclei, in contrast to soft acids.
hard water	Chemistry	1	Water that has very high mineral content, generally formed when water percolates through deposits rich in calcium, magnesium, and certain other metal cations.
heat	Chemistry	1	Energy transferred from one system to another by thermal interaction.
heat of fusion	Chemistry	1	See enthalpy of fusion.
heat of vaporization	Chemistry	1	See enthalpy of vaporization.
hess' law of constant heat summation	Chemistry	1	A law of physical chemistry which states that the total enthalpy change during the course of a chemical reaction is the same whether the reaction is completed in one step or in multiple steps.
hydrate	Chemistry	1	Any substance that contains water or its constituent elements, or any compound formed by the addition of water or its elements to another molecule.
hydrogen bond	Chemistry	1	A weak attraction which holds two molecules containing hydrogen together. For example, in water two hydrogen atoms are bonded to one oxygen atom.
hydrogenation	Chemistry	1	Any chemical reaction between molecular hydrogen (H2) and another chemical species, typically resulting in the reduction or saturation of the other species by the addition of one or more pairs of hydrogen atoms to a compound or element. The presence of a catalyst is usually required for hydrogenation reactions to occur; non-catalytic hydrogenation takes place only at extreme temperatures.
hydrolysis	Chemistry	1	'hydro' – involving water, 'lysis' – breaking down. When water is involved in the breakdown of a chemical compound into two smaller parts.
hydron	Chemistry	1	The cationic form of atomic hydrogen; i.e. a positively charged hydrogen nucleus of any isotopic composition. Thus the term can refer to a proton (11H+), deuteron (21H+), or triton (31H+).
hydrous	Chemistry	1	Having or containing water molecules, referring especially to water of hydration. Contrast anhydrous.
hydroxide	Chemistry	1	A diatomic anion consisting of a hydrogen atom covalently bonded to an oxygen atom, having an overall negative charge, with the chemical formula OH−; or any member of a class of organic and inorganic compounds containing a hydroxy group, e.g. sodium hydroxide (NaOH).
ideal gas	Chemistry	1	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 gas law and can be analyzed within the framework of statistical mechanics.
ideal gas constant	Chemistry	1	The proportionality constant in the ideal gas law, defined as 0.08206 L·atm/(K·mol).
ideal gas law	Chemistry	1	The equation of state of a hypothetical ideal gas, which states that the volume of such a gas is proportional to the amount of gas and its Kelvin temperature, and inversely proportional to its pressure. The ideal gas law combines Boyle's law, Charles's law, Gay-Lussac's law, and Avogadro's law into a single equation, conventionally formulated as P V = n R T PV=nRT} , where R R} is the ideal gas constant. The relationships between the state variables described in this equation are a good approximation of the behavior of many gases under a wide range of conditions, though there are some limitations.
ideal solution	Chemistry	1	A solution for which the gas phase exhibits thermodynamic properties analogous to those of a mixture of ideal gases.
indicator	Chemistry	1	Something that indicates the state or level of something. In ecology, a species that indicates the existence of certain environmental conditions. In chemistry, a substance that indicates the presence (or absence) of a chemical species at a specific concentration.
induced radioactivity	Chemistry	1	Radioactivity caused by bombarding a stable isotope with elementary particles, forming an unstable, radioactive isotope.
inert	Chemistry	1	A substance that tends to be stable and does not react chemically with other substances. Chemically inactive.
inorganic compound	Chemistry	1	Any chemical compound that does not contain carbon, though there are exceptions. Contrast organic compound.
inorganic chemistry	Chemistry	1	The branch of chemistry concerning the chemical properties and reactions of inorganic compounds. Contrast organic chemistry.
insolubility	Chemistry	1	The inability of a substance (the solute) to form a solution by being dissolved in another substance (the solvent); the opposite of solubility.
inspissation	Chemistry	1	The process of thickening a liquid by any method of dehydration, especially evaporation.
insulator	Chemistry	1	Any material that resists the flow of an electric current. Contrast conductor.
intensive property	Chemistry	1	A physical quantity whose value does not depend on the size of the system or the quantity of matter for which it is measured. Examples include density, temperature, and pressure. Contrast extensive property.
interface	Chemistry	1	The boundary between two spatial regions occupied by different matter, especially by matter in different phases or physical states. See also surface and phase boundary.
intermediate	Chemistry	1	See reactive intermediate.
intermetallic	Chemistry	1	A type of alloy that forms an ordered solid-state compound between two or more metallic elements. Intermetallics are generally hard and brittle, and have useful mechanical properties at high temperatures.
intermolecular force	Chemistry	1	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 of one molecule and the atoms or ions of nearby molecules. Intermolecular forces are weak compared to intramolecular forces such as covalent bonds, which hold individual molecules together.
international union of pure and applied chemistry	Chemistry	1	An international federation of chemists that is recognized as the world authority in developing standards for chemical nomenclature and other methodologies in chemistry.
iupac	Chemistry	1	An international federation of chemists that is recognized as the world authority in developing standards for chemical nomenclature and other methodologies in chemistry.
interstitial compound	Chemistry	1	A compound composed of a transition metal bonded to either hydrogen, boron, carbon, or nitrogen, whose crystal structure consists of closely packed metal ions with the non-metal atoms located in the interstices.
ion	Chemistry	1	A molecule that has gained or lost one or more electrons from its neutral state and therefore possesses a negative or positive electric charge.
ionic bond	Chemistry	1	An electrostatic attraction between oppositely charged ions.
ionic strength	Chemistry	1	A measure of the concentration of ions in a solution, usually expressed in terms of molarity (mol/L solution) or molality (mol/kg solvent).
ionization	Chemistry	1	The breaking up of a chemical compound into separate ions.
isoelectronicity	Chemistry	1	The phenomenon of two or more chemical species (atoms, molecules, ions, etc.) being composed of different elements but having the same number of valence electrons and the same structural arrangement (i.e. the same number of atoms with the same connectivity). Isoelectronic species typically show useful consistency and predictability in their chemical properties.
isomers	Chemistry	1	Ions or molecules with identical chemical formulas but distinct structures or spatial arrangements. Isomers do not necessarily share similar properties. The two main types of isomers are structural isomers and stereoisomers.
isotope	Chemistry	1	A variant of a particular chemical element which differs in the number of neutrons present in the nucleus. All isotopes of a given element have the same number of protons in each atom.
joule	Chemistry	1	The SI unit of energy (symbol: J). One joule is defined as one newton-metre.
j	Chemistry	1	The SI unit of energy (symbol: J). One joule is defined as one newton-metre.
kelvin	Chemistry	1	The SI unit of temperature (symbol: K). The Kelvin scale is an absolute thermodynamic temperature scale that uses absolute zero as its null point.
k	Chemistry	1	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	Chemistry	1	Any organic compound that can be classified as both a ketone and a carboxylic acid, by virtue of containing a keto group and a carboxyl group.
ketone	Chemistry	1	A class of organic compounds and a functional group composed of a carbonyl group between two carbon atoms. Ketones have the general formula R2C=O, where R can be any carbon-containing substituent.
kindling point	Chemistry	1	See autoignition temperature.
kinetics	Chemistry	1	A subfield of chemistry specializing in the study of reaction rates.
kinetic energy	Chemistry	1	The energy of an object due to its motion.
lanthanides	Chemistry	1	The periodic series of metallic elements with atomic numbers 57 through 71, from lanthanum through lutetium.
lattice	Chemistry	1	The unique geometric arrangement of atoms or molecules in a crystalline liquid or solid.
lattice energy	Chemistry	1	The energy released upon the formation of one mole of a crystalline ionic compound from its constituent ions, which are assumed to exist initially in the gaseous state. Lattice energy can be viewed as a measure of the cohesive forces that bind ionic solids; it is therefore directly related to many other physical properties of the solid, including solubility, hardness, and volatility.
leveling effect	Chemistry	1	The effect of a solvent on the chemical properties of acids or bases which are dissolved in the solvent. The strength of a strong acid is limited or "leveled" by the basicity of the solvent, and likewise the strength of a strong base is limited by the acidity of the solvent, such that the effective pH of the solution is higher or lower than might be suggested by the acid's or base's dissociation constant.
ligand	Chemistry	1	An ion, functional group, or other molecule that binds to a central metal atom to form a coordination complex. Such bonding can range from covalent to ionic, but generally involves formal donation of one or more of the ligand's electron pairs to the metal.
light	Chemistry	1	The portion of the electromagnetic spectrum which is visible to the unaided human eye.
liquefaction	Chemistry	1	Any process that generates a liquid from a solid or a gas, or that generates a non-liquid phase that behaves as a fluid.
liquefaction point	Chemistry	1	See melting point.
liquid	Chemistry	1	One of the four fundamental states of matter, characterized by nearly incompressible fluid particles that retain a definite volume but no fixed shape.
london dispersion forces	Chemistry	1	A type of weak intermolecular force.
macromolecule	Chemistry	1	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, substituents, and functional groups). The term is often used interchangeably with polymer.
malleability	Chemistry	1	See ductility.

ethyl

Chemistry

1

The alkyl functional group derived from ethane, consisting of two carbon atoms covalently bonded to each other and fully saturated with bonds to hydrogen atoms, with the chemical formula –CH2CH3. 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 (ethanol), which is often written with the formula CH3CH2OH or EtOH.

eutectic mixture

Chemistry

1

A solid solution consisting of two or more substances which collectively have the lowest melting point of any possible mixture of these components.

extensive property

Chemistry

1

A physical quantity whose value is proportional to the size of the system it describes or to the quantity of matter in the system. Examples include mass, volume, enthalpy, and entropy. Contrast intensive property.

extraction

Chemistry

1

1. A separation process in which a component is separated from its mixture by selective solubility. See also partition.

family

Chemistry

1

See group.

faraday constant

Chemistry

1

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).

f

Chemistry

1

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

Chemistry

1

A set of two laws pertaining to electrolysis which hold that: a) the mass of a substance altered at an electrode during electrolysis is directly proportional to the quantity of electricity transferred at that electrode; and b) the mass of an elemental material altered at an electrode is directly proportional to the element's equivalent weight.

filtration

Chemistry

1

Any physical, biological, or chemical operation that separates large particles (often solid matter) from smaller particles (often a fluid) by passing the mixture through a complex lattice structure through which only particles of a sufficiently small size can pass, called a filter. The fluid and small particles which successfully pass through the filter are called the filtrate.

fire point

Chemistry

1

The lowest temperature at which the vapors above a volatile material will continue to burn for at least five seconds after ignition by an open flame of standard dimension. The fire point should not be confused with the flash point, a slightly lower temperature at which a substance will ignite briefly but at which vapor is not produced at a rate sufficient for sustained combustion.

flash point

Chemistry

1

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 flash point should not be confused with the fire point, which occurs at a slightly higher temperature, nor with the kindling point, which is higher still.

flask

Chemistry

1

A vessel or container, most commonly a type of glassware, widely used in laboratories for a variety of purposes, such as preparing, holding, containing, collecting, and volumetrically measuring chemicals, samples, or solutions, or as a chamber in which a chemical reaction occurs. Flasks come in a number of shapes and sizes but are typically characterized by a relatively wide lower body which tapers into one or more narrower tubular sections with an opening at the top.

flocculation

Chemistry

1

The process by which the dispersed particles in a colloid come out of suspension to aggregate into larger clumps known as floc or flake, either spontaneously or due to the addition of a clarifying agent. The term is often used to refer to a reversible aggregation in which the forces holding the particles together are weak and the colloid can be re-dispersed by agitation.

florence flask

Chemistry

1

See boiling flask.

formal charge

Chemistry

1

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 FC=V-N-{\frac {B}{2}}\ } , where V V} is the number of valence electrons of the neutral atom in its ground state; N N} is the number of valence electrons of the atom which are not participating in bonds in the molecule; and B B} is the number of electrons shared in bonds with other atoms in the molecule.

fc

Chemistry

1

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 FC=V-N-{\frac {B}{2}}\ } , where V V} is the number of valence electrons of the neutral atom in its ground state; N N} is the number of valence electrons of the atom which are not participating in bonds in the molecule; and B B} is the number of electrons shared in bonds with other atoms in the molecule.

formula weight

Chemistry

1

A synonym for molar mass and molecular weight, frequently used for non-molecular compounds such as ionic salts.

fw

Chemistry

1

A synonym for molar mass and molecular weight, frequently used for non-molecular compounds such as ionic salts.

fractional distillation

Chemistry

1

When a mixture containing at least one part liquid is separated into its component parts, or fractions, such as in separating chemical compounds by their boiling point by heating them to a temperature at which several fractions of the compound will evaporate (for example, the refining of crude oil).

fractionation

Chemistry

1

A separation process in which a particular quantity of a mixture is divided during a phase transition into a number of smaller quantities, known as fractions, for which the chemical composition varies according to a gradient. Fractionation exploits subtle differences in some specific property (e.g. mass, boiling point, solubility, etc.) between the mixture's component compounds, making it possible to isolate more than two components of a mixture at the same time. There are many varieties of fractionation employed in many branches of science and technology.

free radical

Chemistry

1

See radical.

freeze-drying

Chemistry

1

See lyophilization.

freezing

Chemistry

1

The phase transition of a substance from a liquid to a solid.

freezing point

Chemistry

1

The temperature at which a substance changes state from a liquid to a solid. Because freezing is the reverse of melting, the freezing point of a substance is identical to its melting point, but by convention only the melting point is referred to as a characteristic property of a substance.

frequency

Chemistry

1

A measurement of the number of cycles of a given process per unit of time. The SI unit for measuring frequency is the hertz (Hz), with 1 Hz = 1 cycle per second.

galvanic cell

Chemistry

1

A type of battery made up of electrochemicals with two different metals connected by a salt bridge.

gas

Chemistry

1

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

Chemistry

1

A type of chromatography commonly used in analytical chemistry to isolate and analyze chemical compounds that can be vaporized without decomposition. Gas chromatography is often used to test the purity of substances, to identify unknown substances, and to measure the relative amounts of the different components of mixtures.

gauche

Chemistry

1

In alkane stereochemistry, a structural conformation involving a torsion angle of ±60°, or a synclinal alignment of functional groups attached to adjacent atoms.

gay-lussac's law

Chemistry

1

A chemical law used for each of the two relationships derived by French chemist Joseph Louis Gay-Lussac and which concern the properties of gases, though the name is more usually applied to his law of combining volumes.

geochemistry

Chemistry

1

The study of the chemistry and chemical composition of the Earth and geological processes.

gibbs energy

Chemistry

1

A value that indicates the spontaneity of a reaction. Usually symbolized as G.

glycol

Chemistry

1

Any of a class of aliphatic dihydric alcohols in which the two hydroxy groups are bonded to two different carbon atoms, which are usually but not necessarily adjacent to each other; e.g. ethylene glycol (HOCH2CH2OH).

gram-atom

Chemistry

1

A former term for a mole.

ground glass joint

Chemistry

1

An apparatus designed to quickly and easily fit two pieces of leak-tight glassware together, featuring ground glass surfaces and typically a custom-made conical taper.

ground state

Chemistry

1

The lowest possible energy state for a given quantum mechanical system, at which the Gibbs energy is actually or theoretically minimized. Whatever energy remains in the system in its ground state is called the zero-point energy. Contrast excited state.

group

Chemistry

1

A vertical column of the periodic table of the elements and the elements that share it. Contrast period.

hadron

Chemistry

1

A subatomic particle of a type including the baryons and mesons that can take part in the strong interaction.

halogen

Chemistry

1

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

Chemistry

1

A Lewis acid with an electron-accepting centre that is only weakly polarizable. Hard acid species also tend to have high charge states and relatively small atomic nuclei, in contrast to soft acids.

hard water

Chemistry

1

Water that has very high mineral content, generally formed when water percolates through deposits rich in calcium, magnesium, and certain other metal cations.

heat

Chemistry

1

Energy transferred from one system to another by thermal interaction.

heat of fusion

Chemistry

1

See enthalpy of fusion.

heat of vaporization

Chemistry

1

See enthalpy of vaporization.

hess' law of constant heat summation

Chemistry

1

A law of physical chemistry which states that the total enthalpy change during the course of a chemical reaction is the same whether the reaction is completed in one step or in multiple steps.

hydrate

Chemistry

1

Any substance that contains water or its constituent elements, or any compound formed by the addition of water or its elements to another molecule.

hydrogen bond

Chemistry

1

A weak attraction which holds two molecules containing hydrogen together. For example, in water two hydrogen atoms are bonded to one oxygen atom.

hydrogenation

Chemistry

1

Any chemical reaction between molecular hydrogen (H2) and another chemical species, typically resulting in the reduction or saturation of the other species by the addition of one or more pairs of hydrogen atoms to a compound or element. The presence of a catalyst is usually required for hydrogenation reactions to occur; non-catalytic hydrogenation takes place only at extreme temperatures.

hydrolysis

Chemistry

1

'hydro' – involving water, 'lysis' – breaking down. When water is involved in the breakdown of a chemical compound into two smaller parts.

hydron

Chemistry

1

The cationic form of atomic hydrogen; i.e. a positively charged hydrogen nucleus of any isotopic composition. Thus the term can refer to a proton (11H+), deuteron (21H+), or triton (31H+).

hydrous

Chemistry

1

Having or containing water molecules, referring especially to water of hydration. Contrast anhydrous.

hydroxide

Chemistry

1

A diatomic anion consisting of a hydrogen atom covalently bonded to an oxygen atom, having an overall negative charge, with the chemical formula OH−; or any member of a class of organic and inorganic compounds containing a hydroxy group, e.g. sodium hydroxide (NaOH).

ideal gas

Chemistry

1

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 gas law and can be analyzed within the framework of statistical mechanics.

ideal gas constant

Chemistry

1

The proportionality constant in the ideal gas law, defined as 0.08206 L·atm/(K·mol).

ideal gas law

Chemistry

1

The equation of state of a hypothetical ideal gas, which states that the volume of such a gas is proportional to the amount of gas and its Kelvin temperature, and inversely proportional to its pressure. The ideal gas law combines Boyle's law, Charles's law, Gay-Lussac's law, and Avogadro's law into a single equation, conventionally formulated as P V = n R T PV=nRT} , where R R} is the ideal gas constant. The relationships between the state variables described in this equation are a good approximation of the behavior of many gases under a wide range of conditions, though there are some limitations.

ideal solution

Chemistry

1

A solution for which the gas phase exhibits thermodynamic properties analogous to those of a mixture of ideal gases.

indicator

Chemistry

1

Something that indicates the state or level of something. In ecology, a species that indicates the existence of certain environmental conditions. In chemistry, a substance that indicates the presence (or absence) of a chemical species at a specific concentration.

induced radioactivity

Chemistry

1

Radioactivity caused by bombarding a stable isotope with elementary particles, forming an unstable, radioactive isotope.

inert

Chemistry

1

A substance that tends to be stable and does not react chemically with other substances. Chemically inactive.

inorganic compound

Chemistry

1

Any chemical compound that does not contain carbon, though there are exceptions. Contrast organic compound.

inorganic chemistry

Chemistry

1

The branch of chemistry concerning the chemical properties and reactions of inorganic compounds. Contrast organic chemistry.

insolubility

Chemistry

1

The inability of a substance (the solute) to form a solution by being dissolved in another substance (the solvent); the opposite of solubility.

inspissation

Chemistry

1

The process of thickening a liquid by any method of dehydration, especially evaporation.

insulator

Chemistry

1

Any material that resists the flow of an electric current. Contrast conductor.

intensive property

Chemistry

1

A physical quantity whose value does not depend on the size of the system or the quantity of matter for which it is measured. Examples include density, temperature, and pressure. Contrast extensive property.

interface

Chemistry

1

The boundary between two spatial regions occupied by different matter, especially by matter in different phases or physical states. See also surface and phase boundary.

intermediate

Chemistry

1

See reactive intermediate.

intermetallic

Chemistry

1

A type of alloy that forms an ordered solid-state compound between two or more metallic elements. Intermetallics are generally hard and brittle, and have useful mechanical properties at high temperatures.

intermolecular force

Chemistry

1

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 of one molecule and the atoms or ions of nearby molecules. Intermolecular forces are weak compared to intramolecular forces such as covalent bonds, which hold individual molecules together.

international union of pure and applied chemistry

Chemistry

1

An international federation of chemists that is recognized as the world authority in developing standards for chemical nomenclature and other methodologies in chemistry.

iupac

Chemistry

1

An international federation of chemists that is recognized as the world authority in developing standards for chemical nomenclature and other methodologies in chemistry.

interstitial compound

Chemistry

1

A compound composed of a transition metal bonded to either hydrogen, boron, carbon, or nitrogen, whose crystal structure consists of closely packed metal ions with the non-metal atoms located in the interstices.

ion

Chemistry

1

A molecule that has gained or lost one or more electrons from its neutral state and therefore possesses a negative or positive electric charge.

ionic bond

Chemistry

1

An electrostatic attraction between oppositely charged ions.

ionic strength

Chemistry

1

A measure of the concentration of ions in a solution, usually expressed in terms of molarity (mol/L solution) or molality (mol/kg solvent).

ionization

Chemistry

1

The breaking up of a chemical compound into separate ions.

isoelectronicity

Chemistry

1

The phenomenon of two or more chemical species (atoms, molecules, ions, etc.) being composed of different elements but having the same number of valence electrons and the same structural arrangement (i.e. the same number of atoms with the same connectivity). Isoelectronic species typically show useful consistency and predictability in their chemical properties.

isomers

Chemistry

1

Ions or molecules with identical chemical formulas but distinct structures or spatial arrangements. Isomers do not necessarily share similar properties. The two main types of isomers are structural isomers and stereoisomers.

isotope

Chemistry

1

A variant of a particular chemical element which differs in the number of neutrons present in the nucleus. All isotopes of a given element have the same number of protons in each atom.

joule

Chemistry

1

The SI unit of energy (symbol: J). One joule is defined as one newton-metre.

j

Chemistry

1

The SI unit of energy (symbol: J). One joule is defined as one newton-metre.

kelvin

Chemistry

1

The SI unit of temperature (symbol: K). The Kelvin scale is an absolute thermodynamic temperature scale that uses absolute zero as its null point.

k

Chemistry

1

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

Chemistry

1

Any organic compound that can be classified as both a ketone and a carboxylic acid, by virtue of containing a keto group and a carboxyl group.

ketone

Chemistry

1

A class of organic compounds and a functional group composed of a carbonyl group between two carbon atoms. Ketones have the general formula R2C=O, where R can be any carbon-containing substituent.

kindling point

Chemistry

1

See autoignition temperature.

kinetics

Chemistry

1

A subfield of chemistry specializing in the study of reaction rates.

kinetic energy

Chemistry

1

The energy of an object due to its motion.

lanthanides

Chemistry

1

The periodic series of metallic elements with atomic numbers 57 through 71, from lanthanum through lutetium.

lattice

Chemistry

1

The unique geometric arrangement of atoms or molecules in a crystalline liquid or solid.

lattice energy

Chemistry

1

The energy released upon the formation of one mole of a crystalline ionic compound from its constituent ions, which are assumed to exist initially in the gaseous state. Lattice energy can be viewed as a measure of the cohesive forces that bind ionic solids; it is therefore directly related to many other physical properties of the solid, including solubility, hardness, and volatility.

leveling effect

Chemistry

1

The effect of a solvent on the chemical properties of acids or bases which are dissolved in the solvent. The strength of a strong acid is limited or "leveled" by the basicity of the solvent, and likewise the strength of a strong base is limited by the acidity of the solvent, such that the effective pH of the solution is higher or lower than might be suggested by the acid's or base's dissociation constant.

ligand

Chemistry

1

An ion, functional group, or other molecule that binds to a central metal atom to form a coordination complex. Such bonding can range from covalent to ionic, but generally involves formal donation of one or more of the ligand's electron pairs to the metal.

light

Chemistry

1

The portion of the electromagnetic spectrum which is visible to the unaided human eye.

liquefaction

Chemistry

1

Any process that generates a liquid from a solid or a gas, or that generates a non-liquid phase that behaves as a fluid.

liquefaction point

Chemistry

1

See melting point.

liquid

Chemistry

1

One of the four fundamental states of matter, characterized by nearly incompressible fluid particles that retain a definite volume but no fixed shape.

london dispersion forces

Chemistry

1

A type of weak intermolecular force.

macromolecule

Chemistry

1

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, substituents, and functional groups). The term is often used interchangeably with polymer.

malleability

Chemistry

1

See ductility.