Chemistry

Lead(II) chloride (PbCl2): properties, occurrence, uses and safety Lead(II) chloride Lead(II) chloride (PbCl2) is a white, sparingly soluble inorganic salt of lead(II) and chloride. It occurs as the mineral cotunnite, forms chloro-complexes, and is toxic; handle an…

Lead(II) oxide (PbO): properties, forms, uses, production and safety Lead(II) oxide Lead(II) oxide (PbO), called litharge or massicot, is the common +2 oxide of lead. It occurs in two crystalline forms, is used in glass, ceramics and pigments, and is toxic — regul…

Lead(II) sulfate (plumbous sulfate) Lead(II) sulfate Lead(II) sulfate (PbSO4) is a sparingly soluble white crystalline lead salt. It occurs naturally as anglesite, forms in lead–acid batteries, and is a toxic heavy‑metal compound req…

Lead(II) sulfide (PbS) Lead(II) sulfide Lead(II) sulfide, PbS, is a dense, black inorganic compound with a rock-salt structure; it occurs as the mineral galena and is a narrow‑gap semiconductor used historically in detec…

Lead(IV) acetate (lead tetraacetate) Lead(IV) acetate Lead(IV) acetate, Pb(C2H3O2)4, is a plumbic acetate used as a powerful organic oxidizing reagent. It cleaves vicinal diols and effects acetoxylation but is highly toxic and now les…

Lead(IV) oxide (lead dioxide, PbO2) Lead(IV) oxide Lead(IV) oxide (PbO2) is a dark brown, crystalline inorganic oxidizer used mainly in lead–acid batteries and electrochemical electrodes; it is toxic and regulated for environmental…

Leaving group (chemistry) Leaving group Definition and role of leaving groups in chemical reactions; factors that control their ability to depart; common examples; and effects on substitution and elimination mechanisms.

Leclanché battery (zinc–carbon cell) Leclanche battery A primary zinc–carbon cell invented by Georges Leclanché in the 19th century. Uses zinc and manganese dioxide with ammonium or zinc chloride electrolytes; largely superseded by alk…

Lewis acid: electron-pair acceptors in chemistry Lewis acid Lewis acids are chemical species that accept electron pairs to form covalent bonds. They play central roles in catalysis, synthesis, materials chemistry and are classified by elect…

Lewis structure (electron-dot diagrams) Lewis structure Diagrammatic method for showing valence electrons, lone pairs, and shared electron pairs in molecules; used to infer bonding, formal charge, resonance, and common exceptions to the…

Lime (building and industrial material) Lime (material) Lime refers to calcium-rich materials and products—principally quicklime and slaked lime—used in construction, agriculture and industry. It originates from limestone and chalk and…

Lime kiln — production of quicklime, types, history and uses Lime kiln A lime kiln is an industrial furnace that converts limestone into quicklime by calcination. This article covers designs, operation, history, common uses, and environmental consider…

Lindane (gamma‑HCH): uses, properties, hazards and regulation Lindane Lindane is the gamma isomer of hexachlorocyclohexane, used historically as an insecticide and in medical treatments; it is persistent, bioaccumulative and widely regulated due to h…

Line notation (chemical and electrochemical text-based representation) Line notation Concise overview of line notation: single-line, ASCII-based systems for representing chemical structures and electrochemical cells, including SMILES, InChI, WLN, syntax, history, u…

Liquefied Petroleum Gas (LPG) Liquefied petroleum gas LPG is a portable mixture of light hydrocarbon gases, mainly propane and butane, stored as a liquid under pressure and used for cooking, heating, industry and as vehicle fuel; hand…

Liquid (state of matter): properties, behavior, and examples Liquid A liquid is a state of matter with definite volume but no fixed shape. This article explains molecular behavior, physical properties, phase changes, pressure in liquids and practic…

Liquid crystal: properties, phases, history and uses Liquid crystal An overview of liquid crystals: what they are, common phases, how they are observed and controlled, historical background, and principal applications such as displays and sensors.

Liquid nitrogen Cryogenic liquid form of atmospheric nitrogen used for cooling, preservation, and industrial processes. Produced by air liquefaction; boils at −196 °C. Requires careful handling du…

List of chemical elements (118 known) List of elements A concise overview of the 118 confirmed chemical elements: their organization in the periodic table, major categories, history of discovery, common uses, and notable facts.

List of chemical elements by symbol List of elements by symbol Overview of how chemical elements are listed by symbol: notation, capitalization, origins of symbols, ordering choices, uses, and representative examples.

R-phrases (Risk Phrases) — EU chemical hazard statements List of R-phrases Standardized EU R‑phrases describe chemical hazards on labels and safety data sheets. They were used with S‑phrases and later replaced by GHS/CLP H‑statements in the EU.

S‑phrases (safety phrases) — standardized precautionary instructions for chemicals List of S-phrases S‑phrases are short, standard safety instructions used in European chemical labelling to advise on storage, handling, first aid, disposal and environmental precautions; historicall…

Lithium: properties, occurrence, uses, and environmental considerations Lithium Lithium is a light, soft alkali metal (symbol Li, atomic number 3) used in batteries, glass, alloys and some medicines. This article explains its properties, sources, applications…

Lithium carbonate (Li2CO3) Lithium carbonate Lithium carbonate is a white inorganic lithium salt used medically as a mood stabilizer and industrially in glass, ceramics, and as a precursor for lithium chemicals and battery ma…

Lithium chloride Lithium chloride (LiCl) is a highly soluble, hygroscopic inorganic salt used in industry and laboratories for drying, synthesis, molten-salt processes and certain biochemical techn…

Lithium hydroxide (LiOH): properties, production, and uses Lithium hydroxide Lithium hydroxide is an inorganic base used in industry and aerospace. This article summarizes its chemical behavior, physical forms, production methods, major applications, and sa…

Lithium nitrate (LiNO3) Lithium nitrate Lithium nitrate is a white, water‑soluble inorganic salt used as an oxidizer and industrial reagent; it appears in pyrotechnics, molten‑salt applications, ceramics, and laboratory…

Lithium nitride (Li3N): properties, structure, preparation and uses Lithium nitride Lithium nitride (Li3N) is the only stable alkali-metal nitride. A red crystalline ionic solid containing Li+ and N3−, it is studied for lithium-ion conduction, hydrogen storage and…

Lithium oxide (Li2O) Lithium oxide Lithium oxide (Li2O) is a white crystalline ionic compound composed of lithium and oxide ions. It is a basic oxide used as a precursor to lithium chemicals and in specialized ceram…

Lithium peroxide (Li2O2): properties, production, uses and safety Lithium peroxide Lithium peroxide (Li2O2) is an inorganic peroxide of lithium. This article covers its structure, methods of preparation, common uses—including oxygen generation and battery chemist…

Litmus paper: a simple pH indicator for acids and bases Litmus paper Litmus paper is a dyed test strip used to indicate whether a solution is acidic or alkaline. Derived historically from lichens, it gives a quick, qualitative pH indication but is n…

Livermorium (Lv) — synthetic element 116 Livermorium Livermorium (Lv, Z=116) is a synthetic, highly radioactive element produced in particle accelerators. It has no stable isotopes and only short-lived atoms, studied for nuclear and…

Lone pair (nonbonding electron pair) Lone pair A lone pair is a pair of valence electrons localized on a single atom that do not participate in covalent bonding; they influence molecular shape, reactivity, and physical properti…

Lubricant: properties, types, uses, history and environmental concerns Lubricant An overview of lubricants: what they are, how they work, common types and additives, principal applications, selection guidance, and environmental and safety issues.

Lutetium (chemical element) Lutetium Lutetium (Lu, atomic number 71) is a dense, silvery-white element often grouped with the lanthanides. It is used in specialized catalysts, medical isotopes, and radiation detectors…

Lycopene — red carotenoid in tomatoes and processed foods Lycopene Lycopene is a red, acyclic carotenoid found in tomatoes and other red fruits. It is a hydrocarbon with formula C40H56, prized as a pigment, dietary compound and food ingredient; re…

Lye: alkaline chemicals, uses, safety, and place names Lye Lye refers to strong alkaline solutions (commonly sodium or potassium hydroxide) used in soap, glass and food processing, and to small towns named Lye in England and France.

Macromolecule: Large Biological and Synthetic Polymers Macromolecule Macromolecules are very large molecules built from repeating subunits (monomers). They include proteins, nucleic acids, carbohydrates, lipids and many synthetic polymers and have d…

Mafic: composition, properties, and geological significance Mafic Mafic describes silicate minerals and igneous rocks rich in magnesium and iron; typically dark, dense, and low in silica. This article explains composition, common minerals and roc…

Magnesium (chemical element) Magnesium Magnesium (Mg, atomic number 12) is a lightweight alkaline earth metal essential to living organisms, abundant in Earth's crust and seawater, used in alloys, agriculture, pyrotechn…

Magnesium oxide (magnesia): properties, uses, and handling Magnesium oxide Magnesium oxide (MgO), a white ionic solid known as magnesia or periclase, is used as a refractory, insulator, antacid, and in agriculture and industry. Overview, production, uses,…

Magnesium sulfate (MgSO4): properties, uses and history Magnesium sulfate Magnesium sulfate (MgSO4), commonly known as Epsom salt, is an inorganic salt used in medicine, agriculture, industry and brewing. It occurs in hydrated and anhydrous forms with va…

Maillard reaction A non-enzymatic reaction between reducing sugars and amino acids that produces browned color, complex flavors and aromas in cooked foods; central to culinary science and relevant t…

Malleability — the ability of a material to be shaped under compressive stress Malleability Malleability is the capacity of a solid, typically a metal, to deform under compressive stress and be formed into sheets or other shapes. This article explains causes, examples, us…

Maltose (malt sugar): structure, occurrence, and uses Maltose Maltose is a reducing disaccharide of two glucose units formed by α‑1,4 linkage; produced during starch breakdown and important in brewing, digestion, and food processing.

Manganate (MnO4^2−): properties, chemistry and uses Manganate Manganate refers to the tetraoxo anion MnO4^2−, a bright green manganese(+6) species analogous to chromate; it appears as an intermediate in permanganate production and has distinc…

Manganese: Properties, Uses, Occurrence, and Biological Roles Manganese Overview of manganese (Mn): physical and chemical properties, industrial uses in steel and batteries, global occurrence and mining, plus its biological roles, dietary importance, a…

Manganese carbonate (manganese(II) carbonate, MnCO3) Manganese carbonate Manganese(II) carbonate (MnCO3) is an inorganic compound occurring as the mineral rhodochrosite; used as a precursor to manganese oxides, pigments and ceramics; decomposes to MnO a…