2-Chlorotoluene

C7H7Cl CAS: 95-49-8 Organic Compounds

2-Chlorotoluene (C7H7Cl) is an organic compound that appears as O-chlorotoluene is a colorless liquid with an aromatic odor. Denser than water and poorly soluble in water. Hence si…

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4-Chlorotoluene

C7H7Cl CAS: 106-43-4 Organic Compounds

4-Chlorotoluene (C7H7Cl) is an organic compound that appears as Colorless liquid; [Hawley] Colorless liquid; mp = 7-9 deg C; [MSDSonline]. It has a molecular weight of 126.58 g/mol…

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Cadmium

Cd CAS: 7440-43-9 Elements

Cadmium is a soft, silvery-white transition metal, atomic number 48. Highly toxic heavy metal and carcinogen. Mainly occurs as a by-product of zinc smelting. Historically used in n…

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Caesium

Cs CAS: 7440-46-2 Elements

Caesium is a soft, gold-coloured alkali metal, atomic number 55. Has the lowest ionisation energy and electronegativity of any stable element. The caesium atomic clock defines the …

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Caffeine

C8H10N4O2 CAS: 58-08-2 Organic Compounds

Caffeine is a trimethylxanthine in which the three methyl groups are located at positions 1, 3, and 7. A purine alkaloid that occurs naturally in tea and coffee. It has a role as a…

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Calcium

Ca CAS: 7440-70-2 Elements

Calcium is a soft, grey alkaline earth metal, atomic number 20. Fifth most abundant element in Earth crust. Essential for life - major component of bones, teeth, shells. Calcium io…

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Calcium acetate

C4H6CaO4 CAS: 62-54-4 Salts

Calcium acetate is the calcium salt of acetic acid. It is used, commonly as a hydrate, to treat hyperphosphataemia (excess phosphate in the blood) in patients with kidney disease: …

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Calcium carbide

CaC2 CAS: 75-20-7 Inorganic Compounds

Calcium carbide (CaC2) is an inorganic compound produced by heating calcium oxide with coke in an electric arc furnace at approximately 2000 °C. It is the primary industrial source…

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Calcium carbonate

CaCO3 CAS: 471-34-1 Salts

Calcium carbonate is a calcium salt with formula CCaO3. It has a role as a fertilizer, an antacid, a food colouring and a food firming agent. It is an inorganic calcium salt, a cal…

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Calcium chloride

CaCl2 CAS: 10043-52-4 Salts

Calcium dichloride is an inorganic calcium salt, a calcium salt and an inorganic chloride. It has a role as a NMR chemical shift reference compound and a fertilizer.

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Calcium fluoride

CaF2 CAS: 7789-75-5 Inorganic Compounds

Calcium fluoride (CaF2) is an inorganic compound that appears as Calcium fluoride appears as odorless gray powder or granules. Sinks in water. (USCG, 1999). It has a molecular weig…

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Calcium hydroxide

Ca(OH)2 CAS: 1305-62-0 Bases & Alkalis

Calcium hydroxide (Ca(OH)2) is a base or alkali that appears as Calcium hydroxide is an odorless white granules. Sinks in water. (USCG, 1999). It has a molecular weight of 74.09 g/…

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Calcium hypochlorite

CaCl2O2 CAS: 7778-54-3 Inorganic Compounds

Calcium hypochlorite is an inorganic calcium salt and a calcium salt. It has a role as a bleaching agent. It contains a hypochlorite.

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Calcium nitrate

CaN2O6 CAS: 10124-37-5 Salts

Calcium nitrate is inorganic nitrate salt of calcium. It has a role as a fertilizer. It is a calcium salt and an inorganic nitrate salt. It contains a calcium(2+).

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Calcium oxide

CaO CAS: 1305-78-8 Inorganic Compounds

Calcium oxide is a member of the class of calcium oxides of calcium and oxygen in a 1:1 ratio. It has a role as a fertilizer.

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Calcium phosphate

Ca3O8P2 CAS: 7758-87-4 Salts

Calcium phosphate (Ca3O8P2) is a salt that appears as Calcium phosphate is an odorless white solid. Sinks and mixes with water. (USCG, 1999). It has a molecular weight of 310.18 g/…

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Calcium silicate

CaH6O8Si2 CAS: 1344-95-2 Inorganic Compounds

Calcium silicate (CaH6O8Si2) is an inorganic compound that appears as Dry Powder; Liquid, Other Solid; Other Solid. It has a molecular weight of 230.29 g/mol. Its IUPAC name is cal…

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Calcium sulfate

CaO4S CAS: 7778-18-9 Salts

Calcium sulfate (CaO4S) is a salt that appears as Calcium sulfate appears as odorless, white powder or colorless, crystalline solid. Crystals sometimes have a blue, gray or reddish…

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Californium

Cf Elements

Californium is a synthetic radioactive actinide and a very strong neutron emitter. It was first produced at the University of California, Berkeley in 1950. It has practical uses as…

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Calorie

The calorie (cal) is a unit of energy defined as the heat needed to raise the temperature of 1 gram of water by 1°C at 15°C. The nutritional Calorie (kcal) equals 1000 calories. In…

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Calorimeter

q = C_cal × ΔT; C_cal determined by combustion of standard (e.g., benzoic acid)

A calorimeter is an insulated device used to measure the heat released or absorbed during a chemical reaction, physical change, or combustion. Common types include the coffee-cup c…

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Camphor

C10H16O CAS: 76-22-2 Organic Compounds

Camphor is a cyclic monoterpene ketone that is bornane bearing an oxo substituent at position 2. A naturally occurring monoterpenoid. It has a role as a plant metabolite. It is a b…

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Canal Ray

Canal rays (also called anode rays or positive rays) are beams of positive ions produced in a discharge tube by removing electrons from gas atoms. They travel in the opposite direc…

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Capillary

h = 2γ cosθ / (ρgr)

A capillary is a very narrow tube, typically with an internal diameter of less than 1 mm, used in chemistry for capillary action, capillary electrophoresis, and melting point deter…

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Capillary Action

h = 2γ cosθ / (ρgr)

Capillary action (capillarity) is the spontaneous rise or fall of a liquid in a narrow tube or porous material due to the interplay of adhesive forces (between liquid and tube) and…

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Capric acid

C10H20O2 CAS: 334-48-5 Acids

Decanoic acid is a C10, straight-chain saturated fatty acid. It has a role as a volatile oil component, an antibacterial agent, an anti-inflammatory agent, a plant metabolite, a hu…

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Caprolactam

C6H11NO CAS: 105-60-2 Organic Compounds

Epsilon-caprolactam is a member of the class of caprolactams that is azepane substituted by an oxo group at position 2. It has a role as a human blood serum metabolite.

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Capsaicin

C18H27NO3 CAS: 404-86-4 Organic Compounds

Capsaicin is a capsaicinoid. It has a role as a TRPV1 agonist, a non-narcotic analgesic and a voltage-gated sodium channel blocker.

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Carbanion

R⁻ (carbanion; carbon bears negative charge)

A carbanion is a carbon-containing anion in which the carbon bears a negative charge, meaning it has three bonds and an unshared pair of electrons. Carbanions are important reactiv…

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Carbazole

C12H9N CAS: 86-74-8 Organic Compounds

Carbazole can cause cancer according to The Environmental Protection Agency (EPA).

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Carbon

C CAS: 7440-44-0 Elements

Carbon is a non-metal, atomic number 6, forming the basis of all known life. Allotropes include diamond, graphite, graphene, and fullerenes. Forms more compounds than any other ele…

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Carbon dioxide

CO2 CAS: 124-38-9 Inorganic Compounds

Carbon dioxide is a one-carbon compound with formula CO2 in which the carbon is attached to each oxygen atom by a double bond. A colourless, odourless gas under normal conditions, …

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Carbon disulfide

CS2 CAS: 75-15-0 Organic Compounds

Carbon Disulfide can cause developmental toxicity, female reproductive toxicity and male reproductive toxicity according to an independent committee of scientific and health expert…

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Carbon monoxide

CO CAS: 630-08-0 Inorganic Compounds

Carbon Monoxide can cause developmental toxicity according to an independent committee of scientific and health experts.

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Carbon tetrachloride

CCl4 CAS: 56-23-5 Organic Compounds

Carbon Tetrachloride can cause cancer according to an independent committee of scientific and health experts.

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Carbonic acid

CH2O3 CAS: 463-79-6 Acids

Carbonic acid is a carbon oxoacid and a chalcocarbonic acid. It has a role as a mouse metabolite. It is a conjugate acid of a hydrogencarbonate.

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Carbonium Ion

R⁺ or R₃C⁺ (carbocation; carbon bears positive charge)

A carbonium ion (carbocation) is a positively charged carbon-containing ion in which a carbon atom bears a positive charge and has only three bonds. Carbocations are important reac…

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Carboxymethyl cellulose

C8H16NaO8 CAS: 9004-32-4 Polymers & Plastics

Carboxymethylcellulose sodium salt is an organic molecular entity. It has a role as a food additive.

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Carcinogen

A carcinogen is a substance, mixture, or radiation that promotes carcinogenesis—the formation of cancer. Chemical carcinogens may act by directly damaging DNA (genotoxic carcinogen…

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Carvone

C10H14O CAS: 99-49-0 Organic Compounds

Carvone is a p-menthane monoterpenoid that consists of cyclohex-2-enone having methyl and isopropenyl substituents at positions 2 and 5, respectively. It has a role as an allergen.…

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Catalyst

Ea reduced via alternative pathway; rate = k[A]^m[B]^n

A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process, by providing an alternative reaction pathway with a lower activation…

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Catechol

C6H6O2 CAS: 120-80-9 Organic Compounds

Catechol can cause cancer according to The World Health Organization's International Agency for Research on Cancer (IARC).

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Catenation

C-C bond formation: Cₙ → Cₙ chains; e.g., carbon: C-C-C-...

Catenation is the ability of atoms of the same element to form long chains or ring structures by bonding with one another. Carbon exhibits catenation to an exceptional degree, form…

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Cathode

Ox + ne⁻ → Red

The cathode is the electrode at which reduction occurs in an electrochemical cell. In an electrolytic cell, the cathode is connected to the negative terminal of the power source, a…

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Cathode Ray Tube

½mv² = eV

A cathode ray tube (CRT) is an evacuated glass tube in which electrons (cathode rays) emitted from a heated cathode are accelerated by an electric field and deflected by electric o…

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Cathodic Protection

Zn → Zn²⁺ + 2e⁻ (sacrificial anode)

Cathodic protection is a technique used to prevent corrosion of metal structures by making them the cathode of an electrochemical cell. This is achieved either by connecting the st…

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Cation

M^n+

A cation is a positively charged ion formed when an atom or molecule loses one or more electrons. Cations are attracted to the negatively charged cathode during electrolysis. Metal…

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Cell Potential

E_cell = E_cathode − E_anode; ΔG = −nFE_cell

Cell potential (electromotive force, EMF) is the voltage or electrical potential difference between the cathode and anode of an electrochemical cell. It is measured in volts and re…

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Cellulose

(C6H10O5)n CAS: 9004-34-6 Polymers & Plastics

Cellulose is the most abundant organic polymer on Earth, serving as the primary structural component of plant cell walls. It is a linear polysaccharide consisting of D-glucose unit…

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Cellulose acetate

(C6H7O2(OOCCH3)n) CAS: 9004-35-7 Polymers & Plastics

Cellulose acetate is produced by treating cellulose with acetic anhydride to acetylate some or all of the hydroxyl groups. Cellulose diacetate (DS 2.4) is used primarily in textile…

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Central Atom

MLₙ

The central atom in a molecule or ion is the atom that is bonded to more atoms than any other, forming the core of the molecular structure. In Lewis structures and VSEPR theory, th…

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Cerium

Ce CAS: 7440-45-1 Elements

Cerium is a soft, silvery, ductile rare earth metal, atomic number 58. Most abundant lanthanide. Pyrophoric as powder or shavings - sparks when struck (used in lighter flints). Cer…

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Cerium(IV) oxide

CeO2 CAS: 1306-38-3 Inorganic Compounds

Ceric oxide is a metal oxide with formula CeO2. It is used for polishing glass, in coatings for infra-red filters to prevent reflection, and as an oxidant and catalyst in organic s…

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Cesium carbonate

Cs2CO3 CAS: 534-17-8 Bases & Alkalis

Cesium carbonate (Cs2CO3) is a base or alkali that appears as Highly deliquescent solid; [Merck Index] White odorless powder or granules; Hygroscopic; [Alfa Aesar MSDS]. It has a m…

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Cesium chloride

CsCl CAS: 7647-17-8 Salts

Caesium chloride is the inorganic chloride salt of caesium; each caesium ion is coordinated by eight chlorine ions. It has a role as a vasoconstrictor agent and a phase-transfer ca…

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Chain Reaction

X• + RH → R• + HX; R• + X₂ → RX + X•

A chain reaction is a self-sustaining sequence of reactions in which one of the products or by-products causes subsequent reactions of the same kind. In nuclear chemistry, a chain …

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Chain Termination Step

R• + R• → R-R; R• + X• → RX

The chain termination step is the final step in a free-radical chain reaction mechanism in which two radicals combine to form a stable non-radical product, ending the chain. Common…

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Charles's Law

V₁/T₁ = V₂/T₂ (at constant P and n); V/T = k

Charles's Law states that at constant pressure, the volume of a fixed amount of ideal gas is directly proportional to its absolute temperature (V ∝ T, or V/T = constant). First pub…

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Chemical Bonds

Chemical bonds are the attractive forces holding atoms together in compounds and molecules. The main types are ionic bonds (electrostatic attraction between oppositely charged ions…

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Chemical Change

A chemical change (chemical reaction) is a process that results in the transformation of one or more substances into different substances with new chemical compositions and propert…

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Chemical Equation

aA + bB → cC + dD (balanced; law of conservation of mass)

A chemical equation is a symbolic representation of a chemical reaction showing the reactants on the left and products on the right, separated by an arrow. Balanced chemical equati…

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Chemical Equilibrium

K_eq = [C]^c[D]^d / ([A]^a[B]^b) at equilibrium; ΔG° = −RT ln K

Chemical equilibrium is the state in a reversible reaction where the rate of the forward reaction equals the rate of the reverse reaction, so that the concentrations of reactants a…

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Chemical Hygiene Officer (CHO)

A Chemical Hygiene Officer (CHO) is a person designated in a laboratory to develop and implement the chemical hygiene plan, ensure compliance with safety regulations, and provide g…

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Chemical Hygiene Plan (CHP)

A Chemical Hygiene Plan (CHP) is a written programme required by OSHA for laboratories working with hazardous chemicals. It outlines the specific work practices, procedures, and po…

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Chemical Kinetics

Rate = k[A]^m[B]^n; k = Ae^(-Ea/RT) (Arrhenius equation)

Chemical kinetics is the branch of physical chemistry concerned with the rates of chemical reactions and the factors that influence them, including concentration, temperature, cata…

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Chemical Periodicity

Chemical periodicity refers to the recurring trends in chemical properties of elements as atomic number increases across the periodic table. Periodic trends include atomic radius, …

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Chloramphenicol

C11H12Cl2N2O5 CAS: 56-75-7 Organic Compounds

Chloramphenicol is an organochlorine compound that is dichloro-substituted acetamide containing a nitrobenzene ring, an amide bond and two alcohol functions. It has a role as a Myc…

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Chlorine

Cl2 CAS: 7782-50-5 Elements

Chlorine is a yellow-green diatomic halogen gas, atomic number 17, with pungent suffocating odour. Powerful oxidising agent and disinfectant. Used as chemical warfare agent in WWI.…

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Chlorine dioxide

ClO2 CAS: 10049-04-4 Inorganic Compounds

Chlorine dioxide (ClO2) is an inorganic compound that appears as Chlorine dioxide hydrate, frozen is an orange colored solid, appearing as a block of ice, with a faint odor of chlo…

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Chloroacetic acid

C2H3ClO2 CAS: 79-11-8 Acids

Chloroacetic acid is a chlorocarboxylic acid that is acetic acid carrying a 2-chloro substituent. It has a role as an alkylating agent and a herbicide. It is a haloacetic acid and …

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Chlorobenzene

C6H5Cl CAS: 108-90-7 Organic Compounds

Chlorobenzene is the simplest member of the class of monochlorobenzenes, that is benzene in which a single hydrogen has been substituted by a chlorine. It has a role as a solvent.

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Chloroethane

C2H5Cl CAS: 75-00-3 Organic Compounds

Chloroethane (Ethyl Chloride) can cause cancer according to The National Toxicology Program.

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Chloroform

CHCl3 CAS: 67-66-3 Organic Compounds

Chloroform can cause cancer and developmental toxicity according to an independent committee of scientific and health experts.

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Chloromethane

CH3Cl CAS: 74-87-3 Organic Compounds

Methyl Chloride can cause developmental toxicity according to The National Institute for Occupational Safety and Health (NIOSH). It can cause male reproductive toxicity according t…

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Chlorosulfuric acid

ClSO3H CAS: 7790-94-5 Acids

Chlorosulfuric acid (ClSO3H) is an acid that appears as Chlorosulfonic acid appears as a colorless to yellow colored fuming liquid with a pungent odor. Density 14.7 lb / gal. Cause…

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Cholecalciferol

C27H44O CAS: 67-97-0 Organic Compounds

Calciol is a hydroxy seco-steroid that is (5Z,7E)-9,10-secocholesta-5,7,10(19)-triene in which the pro-S hydrogen at position 3 has been replaced by a hydroxy group. It is the inac…

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Cholesterol

C27H46O CAS: 57-88-5 Organic Compounds

Cholesterol is a cholestanoid consisting of cholestane having a double bond at the 5,6-position as well as a 3beta-hydroxy group. It has a role as a mouse metabolite, a human metab…

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Chromic acid

H2CrO4 CAS: 7738-94-5 Acids

Chromic acid is a chromium oxoacid. It has a role as an oxidising agent. It is a conjugate acid of a hydrogenchromate.

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Chromium

Cr CAS: 7440-47-3 Elements

Chromium is a hard, lustrous transition metal, atomic number 24. Famous for its corrosion resistance and bright finish in electroplating. Chromium(III) compounds are relatively saf…

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Chromium(III) chloride

CrCl3 CAS: 10025-73-7 Salts

Chromium(III) chloride (CrCl3) is a salt that appears as Chromic chloride appears as blue or green colored crystals dissolved in water. Denser than water. Corrosive to metals.. It …

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Chromium(III) oxide

Cr2O3 CAS: 1308-38-9 Inorganic Compounds

Chromium(III) oxide (Cr2O3) is an inorganic compound that appears as Pellets or Large Crystals, Other Solid; Pellets or Large Crystals; Dry Powder, Pellets or Large Crystals; Dry P…

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Chromium(VI) oxide

CrO3 CAS: 1333-82-0 Inorganic Compounds

Chromium trioxide is a chromium oxide composed of a single chromium bound (oxidation state +6) to three oxygens; the acidic anhydride of chromic acid.

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Chrysene

C18H12 CAS: 218-01-9 Organic Compounds

Chrysene can cause cancer according to The Environmental Protection Agency (EPA).

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Cinnamaldehyde

C9H8O CAS: 104-55-2 Organic Compounds

(E)-cinnamaldehyde is the E (trans) stereoisomer of cinnamaldehyde, the parent of the class of cinnamaldehydes. It has a role as a sensitiser, a hypoglycemic agent, a flavouring ag…

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Cinnamic acid

C9H8O2 CAS: 621-82-9 Acids

Cinnamic acid is a monocarboxylic acid that consists of acrylic acid bearing a phenyl substituent at the 3-position. It is found in Cinnamomum cassia. It has a role as a plant meta…

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Ciprofloxacin

C17H18FN3O3 CAS: 85721-33-1 Organic Compounds

Ciprofloxacin is a quinolone that is quinolin-4(1H)-one bearing cyclopropyl, carboxylic acid, fluoro and piperazin-1-yl substituents at positions 1, 3, 6 and 7, respectively. It ha…

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Cis

Cis is a Latin prefix meaning "on the same side", used in chemistry to describe geometric isomers in which identical or similar substituents are on the same side of a double bond o…

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Cis-Trans Isomerism

Cis-trans isomerism (geometric isomerism) occurs when atoms or groups cannot rotate freely due to a double bond or ring structure, resulting in compounds with the same molecular fo…

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Citral

C10H16O CAS: 5392-40-5 Organic Compounds

Geranial is a monoterpenoid that is (2E,6E)-octa-2,6-dienal substituted by methyl groups at positions 3 and 7. It has a role as a volatile oil component and a plant metabolite. It …

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Citric acid

C6H8O7 CAS: 77-92-9 Acids

Citric acid is a tricarboxylic acid that is propane-1,2,3-tricarboxylic acid bearing a hydroxy substituent at position 2. It is an important metabolite in the pathway of all aerobi…

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Citronellal

C10H18O CAS: 106-23-0 Organic Compounds

Citronellal is a monoterpenoid, the main component of citronella oil which gives it its distinctive lemon aroma. It has a role as a metabolite and an antifungal agent. It is an ald…

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Clay

Al₂Si₂O₅(OH)₄

Clay is a naturally occurring fine-grained mineral material composed mainly of phyllosilicate minerals with layered structures. Clays are important in chemistry as ion-exchange mat…

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Cloud Chamber

A cloud chamber is a particle detector consisting of a sealed container with a supersaturated vapour of water or alcohol. When charged particles (such as alpha or beta particles) p…

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Cobalt

Co CAS: 7440-48-4 Elements

Cobalt is a hard, lustrous, silver-grey transition metal, atomic number 27. Used since antiquity to produce blue colour in glass and ceramics (cobalt blue). Essential trace element…

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Cobalt(II) chloride

CoCl2 CAS: 7646-79-9 Salts

Cobalt dichloride is a cobalt salt in which the cobalt metal is in the +2 oxidation state and the counter-anion is chloride. It is used as an indicator for water in desiccants. It …

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Cobalt(II) oxide

CoO CAS: 1307-96-6 Inorganic Compounds

Cobalt (II) Oxide can cause cancer according to The World Health Organization's International Agency for Research on Cancer (IARC).

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Cobalt(II) sulfate

CoSO4 CAS: 10124-43-3 Salts

Cobalt(2+) sulfate is a compound of cobalt and sulfate in which the ratio of cobalt (+2 oxidation state) to sulfate is 1:1. It contains a cobalt(2+).

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Cocaine

C17H21NO4 CAS: 50-36-2 Organic Compounds

Cocaine can cause developmental toxicity and female reproductive toxicity according to an independent committee of scientific and health experts.

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Codeine

C18H21NO3 CAS: 76-57-3 Organic Compounds

Codeine is a morphinane alkaloid found in the opium poppy, Papaver somniferum var. album; has analgesic, anti-tussive and anti-diarrhoeal properties. It has a role as an opioid ana…

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Coefficient of Expansion

α = (1/L)(dL/dT); β = (1/V)(dV/dT) ≈ 3α

The coefficient of thermal expansion is a measure of how much a material expands per degree of temperature increase. For gases, the volume coefficient of expansion at constant pres…

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Cohesive Forces

Cohesion ∝ γ (surface tension); W_cohesion = 2γ

Cohesive forces are the intermolecular attractive forces between like molecules in a substance. These forces are responsible for surface tension and the tendency of liquids to mini…

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Coke

Coke is a solid carbonaceous material produced by the destructive distillation (coking) of coal in the absence of air. It consists mainly of carbon with small amounts of hydrogen, …

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Colligative Properties

ΔT_b = K_b·m; ΔT_f = K_f·m; Π = MRT; ΔP/P° = x_solute (Raoult)

Colligative properties are properties of solutions that depend on the number of solute particles (molecules or ions) rather than on the nature of the solute. The four main colligat…

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Collision Theory

Δ[A]/Δt = k[A]^m or reaction rate ∝ Z × f (collision frequency × fraction effective)

Collision theory explains chemical reaction rates by proposing that reactions occur only when reactant molecules collide with sufficient energy (greater than or equal to the activa…

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Colloid

A colloid (colloidal dispersion) is a mixture in which particles of one substance (1–1000 nm in size) are dispersed throughout another but not dissolved. Colloids differ from true …

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Combination Reaction

A + B → AB (synthesis); e.g., 2Mg + O₂ → 2MgO

A combination reaction (synthesis reaction) is a reaction in which two or more substances combine to form a single product. The general form is A + B → AB. Examples include iron re…

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Combustible

Flash point 60–93°C

A combustible substance is one capable of burning in oxygen to produce heat and light. In regulatory contexts, combustible liquids typically have flash points above 37.8°C (100°F),…

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Common Ion Effect

The common ion effect is the decrease in solubility of a sparingly soluble salt when a solution already containing one of its ions is added. For example, the solubility of AgCl dec…

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Complex Ions

[ML_n]^x+; stability: β_n = [ML_n]/([M][L]^n)

Complex ions (coordination ions) consist of a central metal ion bonded to a number of ligands (molecules or anions with lone pairs) through coordinate (dative) covalent bonds. The …

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Composition Stoichiometry

mass% A = (mass A / total mass) × 100; mole% = (moles A / total moles) × 100

Composition stoichiometry involves calculating the quantitative relationships between elements in a compound, expressed as percentages by mass or mole ratios. It uses the chemical …

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Compound

Composed of ≥2 elements in fixed ratio; e.g., H₂O, NaCl, CaCO₃

A compound is a pure substance consisting of two or more different elements chemically bonded together in a fixed ratio by mass. Compounds have properties different from their cons…

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Compressed Gas

PV = nRT

A compressed gas is any gas stored under pressure in a cylinder or container. Compressed gases include oxygen, nitrogen, hydrogen, acetylene, and carbon dioxide cylinders used in l…

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Concentration

C = n/V (mol/L) or mass/volume (g/L) or ppm (mg/L)

Concentration is the amount of solute dissolved in a given volume or mass of solvent or solution. Common units include molarity (mol/L), molality (mol/kg), mass percent (%), and pa…

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Condensation

Gas → Liquid: ΔH_cond = −ΔH_vap (exothermic)

In chemistry, condensation refers to two related phenomena: (1) a phase change in which a vapour converts to a liquid by releasing heat, and (2) a condensation reaction (condensati…

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Condensed Phases

Condensed phases are the solid and liquid states of matter, as distinct from the gaseous state. In condensed phases, particles are in close contact and intermolecular forces are si…

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Condensed States

Condensed states refer to the solid and liquid phases of matter in which atoms or molecules are closely packed together, in contrast to the vapour phase. The term is often used int…

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Conduction Band

Band gap: E_g; conduction band above valence band; metals: E_g = 0

The conduction band is the range of electron energies in a solid at which electrons can move freely and conduct electricity. In conductors (metals), the conduction band overlaps wi…

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Conformations

Described by dihedral angle φ; Newman projections; staggered vs eclipsed

Conformations are the different three-dimensional arrangements of atoms in a molecule that arise from rotation about single bonds, without breaking any bonds. In cyclohexane, the m…

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Congo red

C32H22N6Na2O6S2 CAS: 573-58-0 Indicators

Congo Red is an indicator dye that is blue-violet at pH 3.0 and red at pH 5.0. It contains a 3,3'-(biphenyl-4,4'-diyldidiazene-2,1-diyl)bis(4-aminonaphthalene-1-sulfonate). It is f…

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Conjugate Acid-Base Pair

pKa + pKb = pKw = 14

A conjugate acid-base pair consists of two species related by the gain or loss of a single proton (H⁺). The conjugate base is formed when an acid loses a proton; the conjugate acid…

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Conjugated Double Bonds

Alternating C=C-C=C; delocalisation extends over π system: λ_abs > isolated alkene

Conjugated double bonds are alternating single and double bonds in a molecule, creating a system of overlapping p orbitals in which pi electrons are delocalised across multiple ato…

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Contact Process

2SO₂+O₂⇌2SO₃ (V₂O₅, 450°C); SO₃+H₂SO₄→H₂S₂O₇+H₂O→2H₂SO₄

The Contact Process is the industrial method for manufacturing sulfuric acid (H₂SO₄). It involves: (1) burning sulfur or roasting metal sulfides to form SO₂, (2) catalytic oxidatio…

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Continuous Spectrum

A continuous spectrum contains all wavelengths of electromagnetic radiation within a range, appearing as a rainbow of colours with no gaps. It is produced by hot dense objects (sol…

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Control Rods

¹⁰B + n → ⁷Li + ⁴He

Control rods are neutron-absorbing rods inserted into a nuclear reactor to regulate the rate of the fission chain reaction. Made of materials with high neutron-absorption cross-sec…

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Coomassie Brilliant Blue R-250

C47H48N3NaO7S2 CAS: 6104-58-1 Laboratory Reagents

Coomassie Brilliant Blue R-250 (C47H48N3NaO7S2) is a laboratory reagent that appears as Blue crystals; [MSDSonline]. It has a molecular weight of 854.0 g/mol. Its IUPAC name is sod…

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Coordinate Covalent Bond

L: → M (donor-acceptor bond; also called dative bond)

A coordinate covalent bond (dative bond) is a covalent bond in which both electrons in the shared pair are donated by the same atom, called the donor. The atom accepting the electr…

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Coordination Compound or Complex

[ML_n]^x; IUPAC name: [ligands alphabetically, metal, charge]

A coordination compound (or complex) consists of a central atom or ion (usually a transition metal) surrounded by a set of ligands bonded to it through coordinate covalent bonds. T…

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Coordination Isomers

Coordination isomers are isomers of coordination compounds in which the ligands are distributed differently between the cationic and anionic parts of the coordination complex. For …

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Coordination Number

CN = number of donor atoms bonded to central metal; common: 2, 4, 6

The coordination number in a coordination compound is the number of donor atoms (from ligands) directly bonded to the central metal ion. Common coordination numbers are 2 (linear),…

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Coordination Sphere

[MLₙ]^x (inner sphere)

The coordination sphere of a complex consists of the central metal atom or ion together with all ligands directly bonded to it. It is usually enclosed in square brackets in the for…

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Copernicium

Cn Elements

Copernicium is a synthetic radioactive transactinide element named after Nicolaus Copernicus. It may be a gas at room temperature due to relativistic effects. First synthesised in …

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Copper

Cu

Copper (Cu, atomic number 29) is a soft, malleable, ductile metal with high electrical and thermal conductivity. It was one of the first metals used by humans. Copper forms +1 (cup…

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Copper

Cu Elements

Copper is a ductile, malleable transition metal with excellent electrical and thermal conductivity. One of the few naturally occurring metallic elements, copper has been used by hu…

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Copper(I) bromide

BrCu CAS: 7787-70-4 Laboratory Reagents

Copper(I) bromide (BrCu) is a laboratory reagent that appears as Copper (i) bromide appears as white powder or crystal. Turns green to dark blue on exposure to sunlight. Sinks and …

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Copper(I) iodide

CuI CAS: 7681-65-4 Laboratory Reagents

Copper(I) iodide (CuI) is a laboratory reagent that appears as Pellets or Large Crystals; Dry Powder. It has a molecular weight of 190.45 g/mol. Its IUPAC name is copper(1+) iodide…

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Copper(I) oxide

Cu2O CAS: 1317-39-1 Inorganic Compounds

Copper(I) oxide (Cu2O) is an inorganic compound that appears as Liquid; Water or Solvent Wet Solid; Dry Powder; Other Solid. It has a molecular weight of 143.09 g/mol. Its IUPAC na…

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Copper(II) chloride

CuCl2 CAS: 7447-39-4 Salts

Copper(II) chloride is an inorganic chloride of copper in which the metal is in the +2 oxidation state. It has a role as an EC 5.3.3.5 (cholestenol Delta-isomerase) inhibitor. It i…

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Copper(II) nitrate

CuN2O6 CAS: 3251-23-8 Salts

Copper(II) nitrate is an inorganic nitrate salt having copper(2+) as the couterion. It contains a copper(2+).

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Copper(II) oxide

CuO CAS: 1317-38-0 Inorganic Compounds

Copper(II) oxide is a metal oxide that has the formula CuO. It has an ionic structure. It contains a copper(2+).

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Copper(II) sulfate

CuSO4 CAS: 7758-98-7 Salts

Copper(II) sulfate is a metal sulfate compound having copper(2+) as the metal ion. It has a role as a sensitiser, an emetic and a fertilizer. It contains a copper(2+).

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Corrosion

Fe → Fe²⁺ + 2e⁻; O₂ + 2H₂O + 4e⁻ → 4OH⁻

Corrosion is the gradual destruction of a material (usually a metal) by chemical reaction with its environment, particularly oxidation by oxygen and moisture. The most familiar exa…

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Cortisol

C21H30O5 CAS: 50-23-7 Organic Compounds

Cortisol is a 17alpha-hydroxy-C21-steroid that is pregn-4-ene substituted by oxo groups at positions 3 and 20 and hydroxy groups at positions 11, 17 and 21. Cortisol is a corticost…

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Coulomb

F = kq₁q₂/r² (Coulomb's law); 1 C = charge of ~6.242 × 10¹⁸ protons

The coulomb (C) is the SI unit of electric charge, equal to the charge transported by a current of one ampere in one second. In Faraday's laws of electrolysis, one faraday (96,485 …

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Coulometry

Q = ∫I dt; n = Q/(nF)

Coulometry is an electroanalytical method that measures the quantity of charge (in coulombs) required to completely convert an analyte from one oxidation state to another. Using Fa…

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Coumarin

C9H6O2 CAS: 91-64-5 Organic Compounds

Coumarin is a chromenone having the keto group located at the 2-position. It has a role as a fluorescent dye, a plant metabolite and a human metabolite.

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Covalent Bond

A:B (shared electron pair) | e.g., H₂: H−H, H₂O: H−O−H

A covalent bond is a chemical bond formed by the sharing of one or more pairs of electrons between two atoms, typically between non-metal atoms. Single bonds share one pair, double…

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Covalent Compounds

Covalent compounds are substances whose atoms are held together by covalent bonds rather than ionic bonds. They consist of discrete molecules (molecular compounds) or extended cova…

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Cresol red

C21H18O5S CAS: 1733-12-6 Indicators

Cresol red is a member of the class of 2,1-benzoxathioles that is 2,1-benzoxathiole 1,1-dioxide in which both of the hydrogens at position 3 have been substituted by 4-hydroxy-5-me…

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Critical Mass

m_crit = π²D/(νΣ_f) for sphere; depends on geometry and material

Critical mass is the minimum mass of fissile material (such as uranium-235 or plutonium-239) needed to sustain a self-propagating nuclear chain reaction. If the mass is below criti…

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Critical Point

The critical point of a substance is the temperature and pressure above which the distinction between liquid and vapour phases disappears, forming a supercritical fluid. At the cri…

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Critical Pressure

Critical pressure is the minimum pressure required to liquefy a gas at its critical temperature. Above the critical temperature, no amount of pressure can liquefy the gas. Critical…

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Critical Temperature

Critical temperature is the temperature above which a gas cannot be liquefied by applying pressure alone, regardless of how high the pressure is. Below the critical temperature, su…

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Crystal Field Stabilization Energy

CFSE = Δ_oct × [(-0.4)(t₂g electrons) + (0.6)(eg electrons)] for octahedral

Crystal Field Stabilization Energy (CFSE) is the stabilisation energy gained by a transition metal complex due to the splitting of d orbitals in a crystal field (ligand field). Ele…

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Crystal Field Theory

Δ_oct (octahedral splitting); Δ_tet = (4/9)Δ_oct (tetrahedral splitting)

Crystal Field Theory (CFT) is a model that describes the electronic structure of transition metal complexes by considering the effect of a surrounding array of negative charges (li…

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Crystal Lattice

Described by Bravais lattice; unit cell vectors a, b, c and angles α, β, γ

A crystal lattice is the regular, three-dimensional arrangement of atoms, ions, or molecules in a crystalline solid. Lattice points represent the positions of particles and are des…

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Crystal Lattice Energy

U = −Mz₊z₋e²NA / (4πε₀r₀)(1 − 1/n); Born-Landé equation

Crystal lattice energy (lattice enthalpy) is the energy released when one mole of a crystalline ionic compound is formed from its gaseous ions at infinite separation, or equivalent…

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Crystal violet

C25H30ClN3 CAS: 548-62-9 Indicators

Gentian Violet can cause cancer according to an independent committee of scientific and health experts.

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Crystalline Solid

nλ = 2d sinθ (Bragg)

A crystalline solid is a solid in which the particles (atoms, ions, or molecules) are arranged in a highly ordered, repeating three-dimensional pattern called a crystal lattice. Cr…

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Cumene

C9H12 CAS: 98-82-8 Organic Compounds

Cumene (C9H12) is an organic compound that appears as Cumene appears as a clear colorless liquid with an aromatic odor. Less dense than water and insoluble in water. Vapors heavier…

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Curcumin

C21H20O6 CAS: 458-37-7 Organic Compounds

Curcumin is a beta-diketone that is methane in which two of the hydrogens are substituted by feruloyl groups. A natural dyestuff found in the root of Curcuma longa. It has a role a…

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Curie (Ci)

1 Ci = 3.7 × 10¹⁰ disintegrations per second (dps)

The curie (Ci) is a non-SI unit of radioactivity, defined as the amount of a radioactive substance that undergoes 3.7 × 10¹⁰ disintegrations per second (the activity of 1 gram of r…

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Curium

Cm Elements

Curium is a transuranic radioactive actinide named in honour of Pierre and Marie Curie. It was the third transuranic element to be discovered. Curium-244 is used as an alpha-partic…

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Cyanocobalamin

C63H88CoN14O14P CAS: 68-19-9 Organic Compounds

Cyanocobalamin (C63H88CoN14O14P) is an organic compound that appears as Dark red odorless solid; Hygroscopic; [Merck Index] Dark red powder; [Sigma-Aldrich MSDS]. It has a molecula…

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Cyclohexane

C6H12 CAS: 110-82-7 Organic Compounds

Cyclohexane is an alicyclic hydrocarbon comprising a ring of six carbon atoms; the cyclic form of hexane, used as a raw material in the manufacture of nylon. It has a role as a non…

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Cyclohexanol

C6H12O CAS: 108-93-0 Organic Compounds

Cyclohexanol is an alcohol that consists of cyclohexane bearing a single hydroxy substituent. The parent of the class of cyclohexanols. It has a role as a solvent. It is a member o…

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Cyclohexanone

C6H10O CAS: 108-94-1 Organic Compounds

Cyclohexanone is a cyclic ketone that consists of cyclohexane bearing a single oxo substituent. It has a role as a human xenobiotic metabolite.

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Cyclohexene

C6H10 CAS: 110-83-8 Organic Compounds

Cyclohexene (C6H10) is an organic compound that appears as Cyclohexene appears as a colorless liquid. Insoluble in water and less dense than water. Flash point 20 °F. Vapors heavie…

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Cyclohexylamine

C6H13N CAS: 108-91-8 Bases & Alkalis

Cyclohexylamine is a primary aliphatic amine consisting of cyclohexane carrying an amino substituent. It has a role as a mouse metabolite and a human xenobiotic metabolite. It is a…

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Cyclopentane

C5H10 CAS: 287-92-3 Organic Compounds

Cyclopentane is a cycloalkane that consists of five carbons each bonded with two hydrogens above and below the plane. The parent of the class of cyclopentanes. It has a role as a n…

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Cyclopentanol

C5H10O CAS: 96-41-3 Organic Compounds

Cyclopentanol is the simplest member of the class of cyclopentanols bearing a single hydroxy substituent. The parent of the class of cyclopentanols.

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Cyclopentanone

C5H8O CAS: 120-92-3 Organic Compounds

Cyclopentanone is a cyclic ketone that consists of cyclopentane bearing a single oxo substituent. It has a role as a Maillard reaction product.

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Cyclopentyl methyl ether

C6H12O CAS: 5614-37-9 Solvents

Cyclopentyl methyl ether (C6H12O) is a solvent. It has a molecular weight of 100.16 g/mol. Its IUPAC name is methoxycyclopentane.

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Cyclotron

f = qB/(2πm)

A cyclotron is a type of circular particle accelerator in which charged particles are accelerated using alternating electric fields and kept on a spiral path by a static magnetic f…

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Cytosine

C4H5N3O CAS: 71-30-7 Organic Compounds

Cytosine is an aminopyrimidine that is pyrimidin-2-one having the amino group located at position 4. It has a role as a mouse metabolite, a Saccharomyces cerevisiae metabolite, an …

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About Chemicals Starting With C

This page lists all chemicals in our database beginning with the letter C. 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.