L
labile
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Reactive; often used to describe coordination complexes which exchange ligands rapidly.
laboratory tissue
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A laboratory tissue is a paper product which is essentially lint free. Laboratory tissues are typically used to wipe liquid off of the outside of pipets or cuvettes for the Spectronic 20.
lanthanide
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An element in the periodic table from lanthanum (atomic number 57) to lutetium (atomic number 71). Sometimes lanthanum itself is not included in this series; also called lanthanoid.
lanthanide contraction
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The effect of filled f orbitals in decreasing the size of atoms appearing after the f block in the periodic table.
lanthanoid
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An element in the periodic table from lanthanum (atomic number 57) to lutetium (atomic number 71). Sometimes lanthanum itself is not included in this series; also called lanthanide.
lattice
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The points in space that define the locations of the repeating units in a crystal.
lattice energy
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The energy absorbed as gaseous ions come together to form an ionic compound. Different textbooks define the sign of this quantity differently.
law of constant composition
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The statement that the mass ratio of elements in a given substance is always the same. Also called the law of definite proportions.
law of definite proportions
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The statement that the mass ratio of elements in a given substance is always the same. Also called the law of constant composition.
law of multiple proportions
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The statement that the values of the mass ratios of two elements in different compounds are themselves in the ratio of small whole numbers.
Le Chatelier's principle
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The idea that a system at equilibrium will respond to a stress placed upon it in such a manner as to partially offset that stress.
leveling effect
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The situation when a basic solvent completely reacts with an acidic solute so the strength of the acid may not be distinguished from other acids with which the solvent reacts completely. The solvent may also be an acid and react with a basic solute.
levorotatory
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Descriptive of a substance that rotates the plane of polarized light to the left.
Lewis acid
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A species that accepts a pair of electrons to form a covalent bond.
Lewis acid-base theory
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The idea that an acid is a species that accepts a pair of electrons to form a covalent bond and a base is a species that donates a pair of electrons to form a covalent bond.
Lewis base
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A species that donates a pair of electrons to form a covalent bond.
Lewis structure
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A representation of the bonding in a covalent molecule that indicates how many electrons are involved in bonding and how many are unshared on each atom; also called electron dot structure.
ligand
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One of the small molecules or ions attached to a central metal ion in a coordination complex.
ligand field theory
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A theory that explains properties of coordination complexes in terms of molecular orbital theory.
limiting reactant
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The reactant (of two or more reactants) present in an amount such that it would be completely consumed if the reaction proceeded to completion.
limiting reagent
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The reactant (of two or more reactants) present in an amount such that it would be completely consumed if the reaction proceeded to completion.
linkage isomer
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One of two or more coordination complexes that have the same chemical composition but that differ in the manner in which ligands are attached to the central metal ion.
lipid
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An organic compound found in tissue and that is soluble in nonpolar solvents.
liquid
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A state of matter in which the particles change position so that the matter takes the shape of its container
liquid crystal
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A state of matter similar to a liquid but which contains some ordered regions more typical of a solid.
liter
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A unit of volume equal to a cubic decimeter.
London dispersion force
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Intermolecular forces arising from an instantaneous dipole in one molecule inducing a dipole in another molecule.
lone pair
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In a covalently bonded molecule or ion, a pair of electrons not involved in the formation of bonds.
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