ideal gas |
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Ideal gas is a gas in which there is complete absence of cohesive forces between the component molecules; the behavior of such a gas can be predicted accurately by the ideal gas equation through all ranges of temperature and pressure. The concept is theoretical, since no actual gas meets the ideal requirement. |
ideal gas law |
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The generalized ideal gas law is derived from a combination of the laws of Boyle and Charles. Ideal gas law is the equation of state
pV = RT
which defines an ideal gas, where p is pressure, V molar volume, T temperature, and R the molar gas constant (8.314 JK-1mol-1). |
ideal solution |
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Ideal solution is a solution in which solvent-solvent and solvent-solute interactions are identical, so that properties such as volume and enthalpy are exactly additive. Ideal solutions follow Raoult's law, which states that the vapor pressure pi of component i is pi = xi pi*, where xi is the mole fraction of component i and pi* the vapor pressure of the pure substance i. |
index of refraction |
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For a non-absorbing medium, index of refraction (n) is the ratio of the velocity of electromagnetic radiation in vacuo to the phase velocity of radiation of a specified frequency in the medium. |
indicator |
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Indicator is a substance used to show the presence of a chemical substance or ion by its colour. Acid-base indicators are compounds, such as phenolphtaleine and methyl orange, that change colour reversibly, depending on whether the solution is acidic or basic. Oxidation-reduction indicators are substances that show a reversible colour change between oxidized and reduced forms. |
insulator |
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Insulator is a material in which the highest occupied energy band (valence band) is completely filled with electrons, while the next higher band (conduction band) is empty. Solids with an energy gap of 5 eV or more are generally considered as insulators at room temperature. Their conductivity is less than 10-6 S/m and increases with temperature. |
international system of units |
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International System of Units (SI) is the unit system adopted by the General Conference on Weights and Measures in 1960 and recommended for use in all scientific and technical fields. It consists of seven base units (meter, kilogram, second, ampere, kelvin, mole, candela), plus derived units and prefixes. |
ion |
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Ion is an atomic or molecular particle having a net electric charge. |
ion exchange |
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Ion exchange is a process involving the adsorption of one or several ionic species accompanied by the simultaneous desorption (displacement) of one or more other ionic species. |
ion exchanger |
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Ion-exchanger is a solid or liquid material containing ions that are exchangeable with other ions with a like charge that are present in a solution in which the material is insoluble. Ion-exchange resins consist of various copolymers having a cross-linked three-dimensional structure to which ionic groups have been attached. |
ionic strength |
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Ionic strength (μ or I) is a measure of the total concentration of ions in a solution, defined by
where zi is the charge of ionic species i and ci is its concentration. |
ionization energy |
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Ionization energy is the minimum energy required to remove an electron from an isolated atom or molecule (in its vibrational ground state) in the gaseous phase. |
isobar |
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Isobar is a line connecting points of equal pressure on a graphical representation of a physical system. |
isobars |
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Isobars are nuclide having the same mass number but different atomic numbers. 54Cr and 54Fe, 112Cd and 112Sn are isobars. |
isochore |
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Isochore is a line or surface of constant volume on a graphical representation of a physical system. |
isoelectric point |
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Isoelectric point is the pH of a solution or dispersion at which the net charge on the macromolecules or colloidal particles is zero. In electrophoresis there is no motion of the particles in an electric field at the isoelectric point. |
isomers |
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Isomers are compounds that have identical molecular formulae but differ in the nature or sequence of bonding of their atoms (structural isomerism) or in the arrangement of their atoms in space (stereoisomerism). |
isomorphism |
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Isomorphism is the existence of two or more substances that have the same crystal structure, so that they form solid solutions. |
isotherm |
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Isotherm is a line connecting points of equal temperature on a graphical representation of a physical system. |
isothermal process |
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Isothermal process is a thermodynamic process in which the temperature of the system does not change. |
isotones |
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Isotones are nuclides having the same neutron number N but different atomic number Z. |
isotopes |
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Isotopes are two or more nuclides with the same atomic number Z but different mass number A. The term is sometimes used synonymously with nuclide, but it is preferable to reserve the word nuclide for a species of specific Z and A. |
isotropy |
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Isotropy is the property of molecules and materials of having identical physical properties in all directions. |
IUPAC |
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International Union of Pure and Applied Chemistry (IUPAC) is a voluntary nonprofit association of national organizations representing chemist in 45 member countries. It was formed in 1919 with the object of facilitating international agreement and uniform practice in both academic and industrial aspects of chemistry. |
