Chemistry Dictionary Terminology "L"

Chemistry Dictionary

Terminology "L"

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Lanthanides

Elements 58 to 71 (after lanthanum)

Lanthanide Contraction

A decrease in the radii of the elements following the lanthanides compared to what would be expected if there were no f-transition metals.

Law of Combining Volumes (Gay-Lussac's Law)

At constant temperature and pressure, the volumes of reacting gases ( and any gaseous products) can be expressed as ratios of small whole numbers;

Law of Conservation of Energy

Energy cannot be created or destroyed; it may be changed from one form to another.

Law of Conservation of Matter

There is no detectable change in the quantity of matter during an ordinary chemical reaction.

Law of Conservation of Matter and Energy

The total amount of matter and energy available in the universe is fixed.

Law of Definite Proportions (Law of Constant Composition)

Different samples of a pure compound always contain the same elements in the same proportions by mass.

Law of Partial Pressures (Dalton's Law)

The total pressure exerted by a mixature of gases is the sum of the partial pressures of the individual gases.

Lead Storage Battery

Secondary voltaic cell used in most automobiles.

Leclanche Cell

A common type of dry cell.

Le Chatelier's Principle

States that a system at equilibrium, or striving to attain equilibrium, responds in such a way as to counteract any stress placed upon it.

If a stress (change of conditions) is applied to a system at equilibrium, the system shifts in the direction that reduces stress.

Leveling Effect

Effect by which all acids stronger than the acid that is characteristic of the solvent react with solvent to produce that acid; similar statement applies to bases. The strongest acid (base) that can exist in a given solvent is the acid (base) characteristic of the solvent.

Levorotatory

Refers to an optically active substance that rotates the plane of plane polarized light counterclockwise; also called levo.

Lewis Acid

Any species that can accept a share in an electron pair.

Lewis Base

Any species that can make available a share in an electron pair.

Lewis Dot Formula (Electron Dot Formula)

Representation of a molecule, ion or formula unit by showing atomic symbols and only outer shell electrons

Ligand

A Lewis base in a coordination compound.

Limiting Reactant

Substance that stoichiometrically limits the amount of product(s) that can be formed.

Linear Accelerator

A device used for accelerating charged particles along a straight line path.

Line Spectrum

An atomic emission or absorption spectrum.

Linkage Isomers

Isomers in which a particular ligand bonds to a metal ion through different donor atoms.

Liquid Aerosol

Colloidal suspension of liquid in gas.

London Forces

Very weak and very short-range attractive forces between short-lived temporary (induced) dipoles; also called dispersion Forces.

Lone Pair

Pair of electrons residing on one atom and not shared by other atoms; unshared pair.

Low Spin Complex

Crystal field designation for an inner orbital complex; contains electrons paired t2g orbitals before eg orbitals are occupied in octahedral complexes.