Water and steam are two different forms of the same chemical substance.

A chemical substance is a material with a definite chemical composition. Materials are physical Substances used as inputs to production or Manufacturing. Use in chemistry In Chemistry, the empirical formula of a Chemical compound is a simple expression of the relative number of each type of Atom It is a concept that became firmly established in the late eighteenth century after work by the chemist Joseph Proust on the composition of some pure chemical compounds such as basic copper carbonate. The term "concept" is traced back to 1554–60 ( l conceptum - something conceived but what is today termed "the classical theory of concepts" is the theory of Aristotle Joseph Louis Proust ( September 26, 1754 - July 5, 1826) was a French Chemist. Copper(II carbonate (often called copper carbonate or cupric carbonate) is a blue-green compound (chemical formula CuCO3 forming part of the ^[1] He deduced that, "All samples of a compound have the same composition; that is, all samples have the same proportions, by mass, of the elements present in the compound. " This is now known as the law of constant composition. In Chemistry, the law of definite proportions and also the elements states that a Chemical compound always contains exactly the same proportion of elements ^[2] Later with the advancement of methods for chemical synthesis particularly in the realm of organic chemistry; the discovery of many more chemical elements and new techniques in the realm of analytical chemistry used for isolation and purification of elements and compounds from chemicals that led to the establishment of modern chemistry, the concept was defined as is found in most chemistry textbooks. In Chemistry, chemical synthesis is purposeful execution of Chemical reactions in order to get a product, or several products Organic chemistry is a discipline within Chemistry which involves the scientific study of the structure properties composition reactions, and preparation Analytical chemistry is the study of the Chemical composition of natural and artificial Materials. A chemical substance is a Material with a definite chemical composition. Chemistry (from Egyptian kēme (chem meaning "earth") is the Science concerned with the composition structure and properties However, there are some controversies regarding this definition mainly because the large number of chemical substances reported in chemistry literature need to be indexed.

A common example of a chemical substance is pure water; it has the same properties and the same ratio of hydrogen to oxygen whether it is isolated from a river or made in a laboratory. Water ( H2[[oxygen O]] H OH) is the most abundant Molecule on Earth 's surface composing of about 70% of the Earth's surface as A ratio is an expression which compares quantities relative to each other Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the A laboratory (informally lab) is a facility that provides controlled conditions in which scientific Research, Experiments and A pure chemical substance cannot be separated into other substances by a process that does not involve any chemical reaction and is rarely found in nature. A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called Some typical chemical substances can be diamond, gold, salt (sodium chloride) and sugar (sucrose). In Mineralogy, diamond is the allotrope of carbon where the carbon atoms are arranged in Gold (ˈɡoʊld is a Chemical element with the symbol Au (from its Latin name aurum) and Atomic number 79 Salt is a Dietary mineral composed primarily of Sodium chloride that is essential for Animal life but toxic to most land plants For sodium chloride in the diet see Salt. Sodium chloride, also known as common salt, table salt, or Halite, is a Sugar is a class of edible Crystalline substances mainly Sucrose, Lactose, and Fructose. Solubility of Pure SucroseTemperature(Cg Generally, chemical substances exist as a solid, liquid, or gas, and may change between these phases of matter with changes in temperature or pressure. A solid' object is in the States of matter characterized by resistance to Deformation and changes of Volume. Liquid is one of the principal States of matter. A liquid is a Fluid that has the particles loose and can freely form a distinct surface at the boundaries of This page is about the physical properties of gas as a state of matter In the Physical sciences a phase is a Set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature Pressure (symbol 'p' is the force per unit Area applied to an object in a direction perpendicular to the surface

Definition

Chemical substances (also sometimes referred to as a pure substances) are often defined as "any material with a definite chemical composition" in most introductory general chemistry textbooks. ^[3] According to this definition a chemical substance can either be a pure chemical element or a pure chemical compound. However, there are exceptions to this definition, a pure substance can also be defined as a form of matter that has both definite composition and distinct properties. Matter is commonly defined as being anything that has mass and that takes up space. ^[4] and the chemical substance index published by CAS also includes several alloys of uncertain composition. Chemical Abstracts Service ( CAS) is a division of the American Chemical Society, and produces Chemical Abstracts, and related products An alloy is a Solid solution or Homogeneous mixture of two or more elements, at least one of which is a Metal, which itself has ^[5] Non-stoichiometric compounds are a special case (in inorganic chemistry) that violates the law of constant composition, and for them, it is sometimes difficult to draw the line between a mixture and a compound, as in the case of palladium hydride. Non-stoichiometric compounds are Chemical compounds with an elemental composition that cannot be represented by a ratio of well-defined Natural numbers and Palladium hydride is metallic Palladium that contains a substantial quantity of Hydrogen within its Crystal lattice.

Elements

Main article: Chemical element

See also: List of elements by name

An element is a chemical substance that is made up of a particular kind of atoms and hence cannot be broken down or transformed by a chemical reaction into a different element, though it can be transmutated into another element through a nuclear reaction. A chemical element is a type of Atom that is distinguished by its Atomic number; that is by the number of Protons in its nucleus. Wikipedia talkFeatured lists for an explanation of this and other inclusion tags below -->This is a list of Chemical elements, sorted by name A chemical element is a type of Atom that is distinguished by its Atomic number; that is by the number of Protons in its nucleus. In Nuclear physics, a nuclear reaction is the process in which two nuclei or nuclear particles collide to produce products different from the initial particles This is so, because all of the atoms in a sample of an element have the same number of protons, though they may be different isotopes, with differing numbers of neutrons. Isotopes (Greek isos = "equal" tópos = "site place" are any of the different types of atoms ( Nuclides

There are about 120 known elements, about 80 of which are stable, that is, they do not change by radioactive decay into other elements, however the number of chemical substances that are elements can be more than 120, because some elements can occur as more than a single chemical substance (allotropes), for instance oxygen as oxygen and ozone. Radioactive decay is the process in which an unstable Atomic nucleus loses energy by emitting ionizing particles and Radiation. Allotropy (Gr allos, other and tropos, manner is a behavior exhibited by certain Chemical elements these elements can exist in two or more different OZONE is an object oriented Operating system written in the C programming language. The majority of elements are classified as metals. The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across These are elements with a characteristic lustre such as iron, copper, and gold. Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 Copper (ˈkɒpɚ is a Chemical element with the symbol Cu (cuprum and Atomic number 29 Gold (ˈɡoʊld is a Chemical element with the symbol Au (from its Latin name aurum) and Atomic number 79 Metals typically conduct electricity and heat well, and they are malleable and ductile. For malleability in Cryptography, see Malleability (cryptography. Ductility is a mechanical property used to describe the extent to which materials can be deformed plastically or "stretched" into "wires" without ^[6] Around a dozen elements,^[7] such as carbon, nitrogen, and oxygen, are classified as non-metals. Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Nonmetal is a term used in Chemistry when classifying the Chemical elements On the basis of their general physical and chemical properties every element in the Non-metals lack the metallic properties described above, they also have a high electronegativity and a tendency to form negative ions called anions. " Electronegativity " is the opposite of " Electropositivity," which describes an element's ability to donate electrons An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge Certain elements such as silicon sometimes resemble metals and sometimes resemble non-metals, and are known as metalloids. Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14 Metalloid is a term used in Chemistry when classifying the Chemical elements On the basis of their general physical and chemical properties nearly every element

Chemical compounds

Main article: Chemical compound

See also: List of organic compounds and List of inorganic compounds

A pure chemical compound is a chemical substance that is composed of a particular set of molecules or ions. A chemical compound is a substance consisting of two or more different elements chemically bonded together in a fixed proportion by Mass. This page aims to list well-known Organic compounds including Organometallic compounds to stimulate the creation of Wikipedia articles Tentative listing related to this page Inorganic compounds by element (presently under construction as well as:CategoryChemical compounds by element. In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge Two or more elements combined into one substance, through a chemical reaction, form what is called a chemical compound. A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called A chemical compound can be either atoms bonded together in molecules or crystals in which atoms, molecules or ions form a crystalline lattice. A chemical bond is the physical process responsible for the attractive interactions between Atoms and Molecules and which confers stability to diatomic and polyatomic In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by In Materials science, a crystal is a Solid in which the constituent Atoms Molecules or Ions are packed in a regularly ordered repeating Compounds based primarily on carbon and hydrogen atoms are called organic compounds, and all others are called inorganic compounds. An organic compound is any member of a large class of Chemical compounds whose Molecules contain Carbon. Traditionally inorganic compounds are considered to be of mineral not biological origin Compounds containing bonds between carbon and a metal are called organometallic compounds. Organometallic chemistry is the study of Chemical compounds containing bonds between Carbon and a Metal.

Compounds in which components share electrons are known as covalent compounds. Compounds consisting of oppositely charged ions are known as ionic compounds, or salts. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge An ionic bond (or electrovalent bond) is a type of Chemical bond that can often form between Metal and Non-metal Ions (or Salt is a Dietary mineral composed primarily of Sodium chloride that is essential for Animal life but toxic to most land plants

In organic chemistry, there can be more than one chemical compound with the same composition and molecular weight. Generally, these are called isomers. This article is about the chemical concept For "isomerism" of atomic nuclei see Nuclear isomer. Isomers usually have substantially different chemical properties, may be isolated and do not spontaneously convert to each other. A common example is glucose vs. Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. fructose. Fructose (also levulose or laevulose) is a simple reducing Sugar ( Monosaccharide) found in many foods and is one of the three The former is an aldehyde, the latter is a ketone. An aldehyde is an organic compound containing a terminal Carbonyl group. A ketone (pronounced as key tone) is either the Functional group characterized by a Carbonyl group (O=C linked to two other Carbon atoms or Their interconversion requires either enzymatic or acid-base catalysis. Glucose-6-phosphate isomerase, or phosphoglucose isomerase, is an Enzyme ( that catalyzes the conversion of Glucose-6-phosphate into Fructose-6-phosphate The Lobry-de Bruyn-van Ekenstein transformation also known as the Lobry-de Bruyn-van-Alberda-van-Ekenstein transformation is a base catalyzed Aldose However, there are also tautomers, where isomerization occurs spontaneously, such that a pure substance cannot be isolated into its tautomers. Tautomers are Organic compounds that are interconvertible by a Chemical reaction called tautomerization. A common example is glucose, which has open-chain and ring forms. Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. One cannot manufacture pure open-chain glucose because glucose spontaneously cyclizes to the hemiacetal form. Hemiacetals and hemiketals are compounds of the general formula R1R2C(OHOR3 where R3 is not a hydrogen

Substances versus mixtures

Main article: Mixture

All matter consists of various elements and chemical compounds, but these are often intimately mixed together. In Chemistry, a mixture is a substance made by combining two or more different materials without a chemical reaction occurring (the objects do not bond together Mixtures contain more than one chemical substance, and they do not have a fixed composition. In principle, they can be separated into the component substances by purely mechanical processes. Mechanics ( Greek) is the branch of Physics concerned with the behaviour of physical bodies when subjected to Forces or displacements Butter, soil and wood are common examples of mixtures. Butter is a Dairy product made by churning fresh or fermented Cream or Milk. Soil, often typeset as SOiL, is a four piece rock band from Chicago Illinois United States founded by Shaun Glass Tom Schofield Tim King and Adam Zadel Wood is hard fibrous lignified structural tissue produced as secondary Xylem in the stems of Woody plants notably trees but also shrubs

Grey iron metal and yellow sulfur are both chemical elements, and they can be mixed together in any ratio to form a yellow-grey mixture. Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 No chemical process occurs, and the material can be identified as a mixture by the fact that the sulfur and the iron can be separated by a mechanical process, such as using a magnet to attract the iron away from the sulfur. A magnet (from Greek grc μαγνήτης λίθος " Magnesian stone" is a material or object that produces a Magnetic field.

In contrast, if iron and sulfur are heated together in a certain ratio (56 grams (1 mol) of iron to 32 grams (1 mol) of sulfur), a chemical reaction takes place and a new substance is formed, the compound iron(II) sulfide, with chemical formula FeS. For other uses of the words gram or gramme see Gram (disambiguation. The mole (symbol mol) is a unit of Amount of substance: it is an SI base unit, and almost the only unit to be used to measure this Iron(II sulfide is a Chemical compound with the formula FeS In practice iron sulfides are often Non-stoichiometric. The resulting compound has all the properties of a chemical substance and is not a mixture. Iron(II) sulfide has its own distinct properties such as melting point and solubility, and the two elements cannot be separated using normal mechanical processes; a magnet will be unable to recover the iron, since there is no metallic iron present in the compound. The melting point of a solid is the temperature range at which it changes state from solid to Liquid. Solubility is the characteristic Physical property referring to the ability of a given substance the Solute, to dissolve in a Solvent.

Chemicals versus chemical substances

While the term chemical substance is a somewhat technical term used most often by professional chemists, the word chemical^[8] is more widely used in the pharmaceutical industry, government and society in general. Thus the word chemical includes a much wider class of substances that includes many mixtures of chemical substances that often find application in many vocations;^[9] and is most commonly used only for artificial or processed substances, such as the products of the chemical industry. The chemical industry comprises the companies that produce industrial chemicals

Naming and indexing

Every chemical substance has one or more systematic names, usually named according to the IUPAC rules for naming. There are millions of possible objects that can be described in science too many to create Common names for every one IUPAC Nomenclature is a system of naming Chemical compounds and of describing the science of Chemistry in general An alternative system is used by the Chemical Abstracts Service (CAS)

Many compounds are also known by their more common, simpler names, many of which predate the systematic name. Chemical Abstracts Service ( CAS) is a division of the American Chemical Society, and produces Chemical Abstracts, and related products For example, the long-known sugar glucose is now systematically named 6-(hydroxymethyl)oxane-2,3,4,5-tetrol. Sugar is a class of edible Crystalline substances mainly Sucrose, Lactose, and Fructose. Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. Natural products and pharmaceuticals are also given simpler names, for example the mild pain-killer Naproxen is the more common name for the chemical compound (S)-6-methoxy-α-methyl-2-naphthaleneacetic acid. Secondary metabolites are Organic compounds that are not directly involved in the normal growth, development or Reproduction of Organisms Naproxen ( INN) (nəˈprɒksən is a Non-steroidal anti-inflammatory drug (NSAID commonly used for the reduction of moderate to severe Pain, Fever

Chemists frequently refer to chemical compounds using chemical formulae or molecular structure of the compound. A chemist is a Scientist trained in the Science of Chemistry. A chemical compound is a substance consisting of two or more different elements chemically bonded together in a fixed proportion by Mass. A chemical formula is a way of expressing information about the Atoms that constitute a particular Chemical compound, and how the relationship between those atoms changes Molecular geometry or molecular structure is the three- Dimensional arrangement of the Atoms that constitute a Molecule. There has been a phenomenal growth in the number of chemical compounds being synthesized (or isolated), and then reported in the scientific literature by professional chemists around the world. Scientific literature comprises scientific Publications that report original empirical and theoretical work in the natural and Social sciences ^[10] An enormous number of chemical compounds are possible through the chemical combination of the known chemical elements. At the last count, about thirty million chemical compounds are known. ^[11] The names of many of these compounds are often nontrivial and hence not very easy to remember or cite accurately. Also it is difficult to keep the track of them in the literature. Several international organizations like the IUPAC and the Chemical Abstract Service (CAS) have intiated steps to make such tasks easier. The International Union of Pure and Applied Chemistry ( IUPAC) (aɪjuːpæk or ay-yoo-pec) is an international Non-governmental organization CAS that provides the abstracting services of the chemical literature, provides a numerical identifier, known as CAS registry number to each chemical substance that has been reported in the chemical literature (such as chemistry journals and patents). CAS registry numbers are unique numerical identifiers for Chemical compounds Polymers biological sequences mixtures and Alloys They are also referred to A patent is a set of Exclusive rights granted by a State to an inventor or his assignee for a fixed period of time in exchange for a disclosure of an This information is compiled as a database and is popularly known as the Chemical substances index. A Computer Database is a structured collection of records or data that is stored in a computer system Other computer-friendly systems that have been developed for substance information, are: SMILES and the International Chemical Identifier or InChI. The IUPAC International Chemical Identifier ( InChI, pronounced "INchee" is a textual Identifier for Chemical substances designed to provide a

Identification of a typical chemical substance

Common name	Systematic name	Chemical formula	Chemical structure	CAS registry number	InChI
alcohol, or ethyl alcohol	ethanol	C2H5OH		[64-17-5]	1/C2H6O/c1-2-3/h3H,2H2,1H3

Isolation, purification, characterisation, and identification

Often a pure substance needs to be isolated from a mixture, for example from a natural source (where a sample often contains numerous chemical substances) or after a chemical reaction (which often give mixtures of chemical substances). IUPAC Nomenclature is a system of naming Chemical compounds and of describing the science of Chemistry in general A chemical formula is a way of expressing information about the Atoms that constitute a particular Chemical compound, and how the relationship between those atoms changes Chemical structure refers to Molecular geometry, Electronic structure and Crystal structure. CAS registry numbers are unique numerical identifiers for Chemical compounds Polymers biological sequences mixtures and Alloys They are also referred to The IUPAC International Chemical Identifier ( InChI, pronounced "INchee" is a textual Identifier for Chemical substances designed to provide a In Chemistry, a mixture is a substance made by combining two or more different materials without a chemical reaction occurring (the objects do not bond together Nature, in the broadest sense is equivalent to the natural world, physical universe, material world or material universe. A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called

Notes and references