Labile
In coordination chemistry, a term describing a complex in which ligand substitution reactions occur rapidly. Labile complexes are kinetically unstable but may be thermodynamically …
Chemical Glossary — Letter L
53 chemicals found starting with "L"
Lanthanide Contraction
The lanthanide contraction is the greater-than-expected decrease in atomic and ionic radii across the lanthanide series (Ce to Lu) due to the poor shielding of nuclear charge by 4f…
Lanthanides
The lanthanides (or lanthanoids) are a series of 15 metallic elements with atomic numbers 57 (lanthanum) to 71 (lutetium), corresponding to the filling of the 4f electron subshell.…
Lanthanides
The series of 14 elements (cerium to lutetium, atomic numbers 58-71) in which the 4f subshell is progressively filled. Also called rare earth elements. Lanthanides have similar che…
Lanthanum
Lanthanum is a soft, silvery-white rare earth metal, atomic number 57, and the first element of the lanthanide series. Highly reactive - tarnishes in air and reacts with water. La2…
Lattice
The regular, repeating three-dimensional arrangement of atoms, ions, or molecules in a crystalline solid. The geometry of the lattice determines crystal structure and properties. T…
Lattice Energy
The energy released when gaseous ions combine to form a solid ionic lattice, or equivalently, the energy required to separate one mole of ionic solid into its constituent gaseous i…
Lattice Structure
A crystal lattice structure is the three-dimensional arrangement of atoms, ions, or molecules in a crystalline solid, forming a regular, repeating pattern. The smallest repeating u…
Law Of Combining Volumes Gay-Lussac's Law
Gay-Lussac's law of combining volumes states that when gases react together and all volumes are measured at the same temperature and pressure, the volumes of reacting gases and gas…
Law of Conservation of Energy
The Law of Conservation of Energy states that energy cannot be created or destroyed, only converted from one form to another. The total energy of an isolated system remains constan…
Law of Conservation of Matter
The principle stating that matter is neither created nor destroyed in ordinary chemical reactions. The total mass of reactants equals the total mass of products. This law requires …
Law Of Conservation Of Matter And Energy
The law of conservation of matter and energy states that the total amount of matter and energy in a closed system remains constant; matter and energy can be converted from one form…
Law of Definite Proportions
Also called Proust's law, it states that a pure compound always contains the same elements in the same proportions by mass regardless of the source or method of preparation. For ex…
Law Of Definite Proportions Law Of Constant Composition
The law of definite proportions (law of constant composition) states that a given chemical compound always contains the same elements in the same fixed ratio by mass, regardless of…
Law of Multiple Proportions
Dalton's law stating that when two elements form more than one compound, the masses of one element that combine with a fixed mass of the other are in simple whole-number ratios. Fo…
Law Of Partial Pressures Dalton's Law
Dalton's law of partial pressures states that the total pressure of a mixture of non-reacting gases is equal to the sum of the partial pressures of each individual gas in the mixtu…
Lawrencium
Lawrencium is the final member of the actinide series and a synthetic radioactive element named after Ernest Lawrence, inventor of the cyclotron. It was first synthesised in 1961 a…
Le Chatelier's Principle
The principle stating that if a system at equilibrium is disturbed by a change in conditions (concentration, pressure, or temperature), the system will shift to partially counterac…
Le Chatelier's Principle
Le Chatelier's principle states that when a system at equilibrium is subjected to an external stress (such as a change in concentration, pressure, temperature, or volume), the syst…
Lead
Lead is a soft, dense, grey post-transition metal, atomic number 82. Used since antiquity. Major environmental and public health concern due to toxicity and persistence. Still exte…
Lead Storage Battery
A lead-acid (lead storage) battery is a rechargeable electrochemical cell in which the anode is lead (Pb), the cathode is lead(IV) oxide (PbO₂), and the electrolyte is sulfuric aci…
Leaving Group
A leaving group is an atom or group of atoms that departs with the bonding electrons during a substitution or elimination reaction. Good leaving groups are stable when they leave a…
Leclanche Cell
The Leclanché cell is a primary (non-rechargeable) electrochemical cell invented by Georges Leclanché in 1866, consisting of a zinc anode, a manganese dioxide cathode, and an ammon…
Leveling Effect
The leveling effect describes the phenomenon in which a solvent limits (levels) the apparent strength of strong acids or bases dissolved in it. In water, all strong acids are compl…
Levorotatory
Levorotatory describes an optically active substance that rotates the plane of polarised light to the left (counterclockwise) when viewed from the detector side. The prefix (–) or …
Levorotatory
A term describing an optically active compound that rotates plane-polarized light in a counterclockwise direction (to the left) when viewed facing the oncoming light. Designated wi…
Lewis Acid
A species that can accept an electron pair from a donor (Lewis base) to form a coordinate bond. Lewis acids are electrophiles. Examples include BF₃, AlCl₃, and metal cations. The L…
Lewis Acid
A Lewis acid is a species that can accept a lone pair of electrons from a Lewis base to form a coordinate covalent bond. Lewis acids are electron-pair acceptors and include metal c…
Lewis Base
A species that can donate an electron pair to an acceptor (Lewis acid) to form a coordinate bond. Lewis bases are nucleophiles and include species with lone pairs of electrons. Exa…
Lewis Base
A Lewis base is a species that can donate a lone pair of electrons to a Lewis acid to form a coordinate covalent bond. Lewis bases are electron-pair donors and include ammonia (NH₃…
Lewis Dot Formula Electron Dot Formula
A Lewis dot formula (electron dot structure) is a structural representation of a molecule or ion that uses dots to depict valence electrons and lines (or pairs of dots) to show bon…
Lewis Dot Structure
A Lewis dot structure (also called Lewis structure or electron dot structure) is a diagram that shows the bonding between atoms of a molecule and the lone pairs of electrons that m…
Lewis Structure
A diagram showing the bonding between atoms in a molecule and the lone pairs of electrons. Lines represent bonding pairs; dots represent lone pairs. Lewis structures follow the oct…
Ligand
An ion or molecule that donates a pair of electrons to a central metal atom or ion to form a coordination complex. Monodentate ligands have one donor atom; polydentate (chelate) li…
Ligand
A ligand is an ion or molecule that donates a lone pair of electrons to a central metal atom or ion to form a coordinate (dative) bond in a coordination compound. Ligands can be mo…
Ligand Field Splitting
Ligand field splitting (crystal field splitting) is the energy difference (Δ or 10Dq) between the two sets of d-orbitals in a transition metal complex, caused by the electrostatic …
Ligand Field Theory
A more complete version of crystal field theory that considers the covalent character of metal-ligand bonds. It uses molecular orbital theory to explain the electronic structure of…
Limiting Reactant
The limiting reactant (or limiting reagent) is the reactant that is completely consumed in a chemical reaction and thereby determines the maximum amount of product that can be form…
Limiting Reagent
The reactant that is completely consumed in a chemical reaction, limiting the amount of product that can be formed. Once the limiting reagent is exhausted, the reaction stops. The …
Line Spectrum
A line spectrum is an emission or absorption spectrum consisting of discrete, sharp lines at specific wavelengths, characteristic of the energy transitions between quantized electr…
Linear Accelerator
A linear accelerator (linac) is a device that accelerates charged subatomic particles (electrons, protons, or heavy ions) along a straight path using alternating electric fields. I…
Linkage Isomers
Linkage isomers are coordination compounds that have the same molecular formula but differ in the atom through which an ambidentate ligand is bonded to the central metal. A classic…
Liquid
A state of matter characterized by definite volume but no definite shape, taking the shape of its container. Liquid molecules are close together with weaker intermolecular forces t…
Liquid Aerosol
A liquid aerosol is a colloidal dispersion of fine liquid droplets suspended in a gas (typically air), such as fog, mist, or spray. The droplets are small enough (typically 0.001–1…
Lithium
Lithium is the lightest metal and least dense solid element, atomic number 3. A soft, silvery-white alkali metal that reacts vigorously with water and tarnishes in air.
Litmus
A natural acid-base indicator derived from lichens that turns red in acidic conditions and blue in basic conditions. Litmus paper (red and blue) is widely used for quick pH testing…
Livermorium
Livermorium is a synthetic radioactive element named after Lawrence Livermore National Laboratory. First synthesised in 2000 through collaboration between Dubna and Livermore. Expe…
London Dispersion Forces
Weak, temporary attractive forces between all molecules arising from instantaneous fluctuations in electron distribution creating temporary dipoles. Also called van der Waals force…
London Forces
London dispersion forces (London forces) are weak, short-range intermolecular forces arising from temporary dipoles induced by fluctuations in the electron distribution of nonpolar…
Lone Pair
A lone pair is a pair of valence electrons in an atom that are not shared with another atom in a covalent bond. Lone pairs influence molecular geometry (as described by VSEPR theor…
Lone Pair
A pair of valence electrons not involved in bonding, residing on a single atom. Lone pairs occupy more space than bonding pairs and repel bonding pairs more strongly, distorting mo…
Low-Spin Complex
A coordination complex in which the crystal field splitting energy is larger than the pairing energy, causing electrons to fill lower d-orbitals before occupying higher ones. Low-s…
Lutetium
Lutetium is a hard, dense, silvery-white rare earth metal, atomic number 71. The heaviest and hardest lanthanide, due to lanthanide contraction. Lu-177 is increasingly important in…
About Chemicals Starting With L
This page lists all chemicals in our database beginning with the letter L. Each entry provides the chemical formula, CAS registry number, physical and chemical properties, common uses, and safety information. Use the alphabetical navigation above to browse other letters, or use the search function to find a specific chemical quickly.
Our chemical glossary covers acids, bases, salts, organic compounds, inorganic compounds, solvents, and many more categories. Click on any chemical name to view its full detailed profile.