C
cal
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Abbreviation for calorie; a unit of energy (or heat or work); equal to 4.184 J.
calcination
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The heating of a solid below its melting point to decompose it, such as the heating of calcium carbonate to drive off carbon dioxide gas and form solid calcium oxide.
calorie
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A unit of energy (or heat or work); equal to 4.184 J; abbreviated cal.
calorimeter
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A device for measuring the heat released or absorbed during a chemical reaction.
capillary action
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The spontaneous movement of a liquid into thin tubes or fibers; determined by adhesive forces, cohesive forces, and surface tension.
carbohydrate
An organic compound having a formula C(H2O)n, or derived from compounds having this formula.
carbonyl
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The functional group of a carbon atom doubly bonded to an oxygen atom; found in aldehydes and ketones.
carboxyl
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The functional group of a carbon atom bonded to a hydroxyl group and doubly bonded to an oxygen atom; found in carboxylic acids: -C(=O)OH.
carboxylic acid
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An organic compound containing the functional group -C(=O)OH.
catalysis
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The increase in rate of a reaction due to the presence of a substance that undergoes no net change during the reaction.
catalyst
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Something that increases the rate of a chemical reaction without itself being a reactant or product.
cathode
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The electrode in an electrochemical cell toward which cations are drawn and where reduction occurs; the negatively charged electrode in a vacuum tube.
cathode rays
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Electrons emitted from the surface of a cathode in a vacuum tube.
cathodic protection
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The attachment of an active metal to a system to protect the system from corrosion. The active metal serves as the anode, making the metal in the system a cathode.
cation
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A positively charged ion, attracted toward the cathode in an electrolytic cell.
ccp
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Abbreviation for cubic closest packed; one of two schemes for closest packing of spheres; described as "abc" to indicate that the atoms of the third layer do not lie directly above the atoms of the first layer.
cell potential
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The voltage of an electrochemical cell; the larger the cell potential, the greater the extent of reaction when equilibrium is reached.
Celsius
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The temperature scale defined by the values 0 °C for the freezing point of water and 100 °C for the boiling point of water; a °C is the same size as a kelvin.
central atom
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In a small molecule or ion, the atom to which the other atoms are bonded.
central metal ion
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The metal ion to which the ligands are attached at the center of a coordination complex
chain isomer
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One of two or more compounds having the same chemical composition but differing in the arrangement of the atoms (usually carbon atoms) forming the backbone of the structure of the compounds; also known as skeletal isomer.
chain reaction
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A reaction in which a product reacts so as to continue the reaction.
chalcogen
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One of the elements in the same column of the periodic table as oxygen.
Charles's law
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The statement that the volume of a sample of gas is directly proportional to the temperature of the gas (at constant pressure).
Chelate
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Used to refer either to a polydentate ligand or to the combination of a polydentate ligand and a central metal ion.
chelating agent
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A polydentate ligand; a molecule or ion which can occupy more than one site in the coordination sphere of a metal ion.
chemical change
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A process in which one or more substances are changed into one or more different substances.
chemical equation
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A representation of a chemical reaction in which chemical symbols represent reactants on the left side and products on the right side.
chemical formula
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A represention of the elemental composition of a species; subscripts are used to indicate the relative numbers of atoms of each kind of element present.
chemical property
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A characteristic of a material that describes the material's chemical composition or reactions.
chemical reaction
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A process in which one or more substances are changed into one or more different substances.
chemical symbol
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A one- or two-letter abbreviation for an individual element.
chiral
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Referring to an ion or molecule that cannot be superimposed on its mirror image.
chromatography
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The separation of a mixture into its components by taking advantage of the components' different affinities for a stationary phase and a mobile phase.
Ci
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Abbreviation for curie; a unit of radioactive decay; equal to 3.70 x 1010 disintegrations per second.
cis
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Describing the relationship between groups attached to two doubly bonded carbon atoms and located on the same side of the double bond. Also referring to groups located adjacent to each other in an octahedral or square planar coordination complex.
clean
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A clean piece of glassware is one which has been washed with soap and water, and rinsed with tap water and then distilled water. No water droplets adhere to it when it is rinsed with distilled water.
codon
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A sequence of three nucleotides that specifies a particular amino acid to go into a protein as it is synthesized.
cohesive force
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An intermolecular force between like molecules, important in the phenomenon of surface tension.
colligative property
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Characteristics of a solution that depend upon the concentration of particles in the solution, but not on the nature of the particles.
collision frequency
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The rate at which chemical species collide; used in theories of chemical kinetics. Also, the frequency with which gaseous molecules collide.
collision theory
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A mathematical description of the number of collisions between molecules in a sample of matter per unit time; useful for predicting rates of reaction.
colloid
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A mixture containing particles larger than those found in a solution but small enough to remain suspended for a very long time.
colloidal dispersion
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A mixture containing particles larger than those found in a solution but small enough to remain suspended for a very long time.
combustion
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The vigorous combination of a material with oxygen gas or other oxidant, often resulting in a flame.
combustion analysis
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A method for determining the chemical composition of a compound by burning the compound under controlled conditions. Often used to determine the relative amounts of carbon and hydrogen in a compound.
common ion effect
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The influence on an equilibrium by the presence of a substance which contains ions that participate in the equilibrium.
complex ion
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An ion formed by the combination of a central metal ion and ligands.
compound
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A material made up of two or more elements and having those elements present in definite proportions.
concentration
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A measure of the ratio of the amount of a substance to the amount of solvent, solution, or ore. Also, the process of making something more concentrated.
concentration cell
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An electrochemical cell in which the two compartments contain the same solutions, but at different concentrations.
condensation
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The process of a liquid forming from vapor.
condensation polymer
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The kind of polymer that is formed by the combination of monomers and the release of a small molecules at the point where monomers are joined.
condensed formula
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A notation for representing which atoms are bonded to which others in a chemical compound without showing the bonds between atoms. For example, CH3CH2OH is the condensed formula for ethanol.
configuration
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One of the spatial arrangements of the atoms in an ion or molecule that differ by which atoms are attached to each other.
conformation
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In an ion or molecule, one of the spatial arrangements which differ by rotation about single bonds, but which do not differ in which atoms are attached to each other.
conjugate acid
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The acid formed when a base accepts a hydrogen ion.
conjugate base
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The base formed when an acid releases a hydrogen ion.
continuous spectrum
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The collection of broad spectral bands of a chemical species; distinguished from a line spectrum in which the bands correspond to individual wavelengths.
control rod
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A rod in a nuclear reactor that variably absorbs neutrons in order to control the rate of fission.
conversion factor
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A ratio with units that is multiplied times a quantity in order to express that quantity in different units.
coordinate covalent bond
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A bond between two atoms in which the shared electrons are considered to be contributed by only one of the atoms.
coordination complex
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An ion or molecule formed by the combination of ligands and a central metal ion.
coordination compound
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The electrically neutral combination of one or more ligands and a central metal ion.
coordination isomer
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One of two or more coordination complexes having the same chemical composition but differing in which ligands are attached to the metal ion(s).
coordination number
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The number of atoms to which an atom is bonded; in a coordination complex, the number of positions where ligands are attached to the central metal ion; in a ionic compound, the number of ions of opposite charge surrounding an ion.
coordination sphere
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In a coordination complex the region around a central metal ion where the ligands are attached to the metal ion.
corrosion
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The structural degradation of a metal or alloy by electrochemical oxidation.
covalent bond
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The attachment of atoms to one another by the presence of a pair of shared electrons.
covalent compound
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A compound in which atoms are attached to one another by the presence of pairs of shared electrons.
covalent radius
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An indication of the size of an atom in a covalent compound; often measured as half the internuclear distance between like atoms bonded to each other.
critical mass
-
The minimum mass of a fissionable nucleus necessary for a sustained chain reaction to occur.
critical point
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The conditions of temperature and pressure above which no distinction exists between a liquid and its vapor.
critical pressure
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The pressure required to convert a gas to a liquid at the critical temperature of a substance.
critical temperature
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The highest temperature at which the vapor of a substance can be converted to a liquid.
cryogenics
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The study of the behavior of matter at temperatures below -200°C.
crystal
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A solid form in which the atoms, molecules, or ions are arranged in a regular, repeating fashion.
crystal field theory
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A theory that explains properties of coordination complexes in terms of electrostatic attractions between the ligands and the metal ion and the resulting different energies of d orbitals.
crystal lattice
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The points in space that define the locations of the repeating units in a crystal.
cubic closest packed
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One of two schemes for closest packing of spheres; described as "abc" to indicate that the atoms of the third layer do not lie directly above the atoms of the first layer.
curie
-
A unit of radioactive decay; equal to 3.70 x 1010 disintegrations per second; abbreviated Ci.
cuvette
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A cuvette is a vessel used to hold a sample within a spectrophotometer.
cycloalkane
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A hydrocarbon containing no multiple bonds between carbon atoms and containing a ring of carbon atoms.
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