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A chemical compound is a
chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which ...
composed of many identical
molecule A scanning tunneling microscopy image of pentacene molecules, which consist of linear chains of five carbon rings. A molecule is an electrically Electricity is the set of physical phenomena associated with the presence and motion I ...

molecule
s (or molecular entities) composed of
atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atom ...

atom
s from more than one
element Element may refer to: Science * Chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all ...
held together by
chemical bond A chemical bond is a lasting attraction between atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday ...
s. A molecule consisting of atoms of only one element is therefore not a compound. There are four types of compounds, depending on how the constituent atoms are held together: *
molecule A scanning tunneling microscopy image of pentacene molecules, which consist of linear chains of five carbon rings. A molecule is an electrically Electricity is the set of physical phenomena associated with the presence and motion I ...

molecule
s held together by
covalent bond A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs, and the stable balance of attractive and repulsive forces between atoms, when they s ...
s *
ionic compound structure of sodium chloride, NaCl, a typical ionic compound. The purple spheres represent sodium cations, Na+, and the green spheres represent chloride anions, Cl−. The yellow stipples show the electrostatic forces. In chemistry, an ionic compo ...
s held together by
ionic bond Ionic bonding is a type of chemical bond A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. The bond may result from the Coulomb's law, electrostatic force of attraction be ...
s *
intermetallic compounds An intermetallic (also called an intermetallic compound, intermetallic alloy, ordered intermetallic alloy, and a long-range-ordered alloy) is a type of metallic alloy An alloy is an admixture of metal A metal (from Ancient Greek, Gree ...
held together by
metallic bond Metallic bonding is a type of chemical bond A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. The bond may result from the Coulomb's law, electrostatic force of att ...
s * certain complexes held together by
coordinate covalent bondA coordinate covalent bond, also known as a dative bond, dipolar bond, or coordinate bond is a kind of two-center, two-electron covalent bond A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms. These ele ...
s. A
chemical formula A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes also other symbols, such as parentheses, dashes, brackets, commas and ...
specifies the number of atoms of each element in a compound molecule, using the standard abbreviations for the chemical elements and numerical
subscript A subscript or superscript is a character (such as a number or letter) that is set slightly below or above the normal line of type, respectively. It is usually smaller than the rest of the text. Subscripts appear at or below the , while supersc ...

subscript
s. For example, a
water Water (chemical formula H2O) is an , transparent, tasteless, odorless, and , which is the main constituent of 's and the s of all known living organisms (in which it acts as a ). It is vital for all known forms of , even though it provide ...

water
molecule has formula H2O indicating two
hydrogen Hydrogen is the chemical element with the Symbol (chemistry), symbol H and atomic number 1. Hydrogen is the lightest element. At standard temperature and pressure, standard conditions hydrogen is a gas of diatomic molecules having the che ...

hydrogen
atoms bonded to one
oxygen Oxygen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same ...

oxygen
atom. Many
chemical A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which ...

chemical
compounds have a unique
CAS number A CAS Registry Number, also referred to as CASRN or CAS Number, is a unique numerical identifier An identifier is a name that identifies (that is, labels the identity of) either a unique object or a unique ''class'' of objects, where the "object" ...
identifier assigned by the
Chemical Abstracts Service Chemical Abstracts Service (CAS) is a division of the American Chemical Society The American Chemical Society (ACS) is a scientific society A learned society (; also known as a learned academy, scholarly society, or academic association) i ...
. Globally, more than 350,000 chemical compounds (including mixtures of chemicals) have been registered for production and use. A compound can be converted to a different chemical substance by interaction with a second substance via a
chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and t ...

chemical reaction
. In this process, bonds between atoms may be broken in either or both of the interacting substances, and new bonds formed.


Definitions

Any substance consisting of two or more different types of
atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atom ...

atom
s (
chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical elements cannot be broken down into simp ...
s) in a fixed
stoichiometric Stoichiometry is the calculation of reactants and products in chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical A chemical s ...
proportion can be termed a ''chemical compound''; the concept is most readily understood when considering pure
chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which ...
s. It follows from their being composed of fixed proportions of two or more types of atoms that chemical compounds can be converted, via
chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and t ...

chemical reaction
, into compounds or substances each having fewer atoms. The ratio of each element in the compound is expressed in a ratio in its chemical formula. A
chemical formula A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes also other symbols, such as parentheses, dashes, brackets, commas and ...
is a way of expressing information about the proportions of atoms that constitute a particular chemical compound, using the standard abbreviations for the chemical elements, and
subscript A subscript or superscript is a character (such as a number or letter) that is set slightly below or above the normal line of type, respectively. It is usually smaller than the rest of the text. Subscripts appear at or below the , while supersc ...

subscript
s to indicate the number of atoms involved. For example,
water Water (chemical formula H2O) is an , transparent, tasteless, odorless, and , which is the main constituent of 's and the s of all known living organisms (in which it acts as a ). It is vital for all known forms of , even though it provide ...

water
is composed of two
hydrogen atom A hydrogen atom is an atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touch ...

hydrogen atom
s bonded to one
oxygen Oxygen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same ...

oxygen
atom: the chemical formula is H2O. In the case of
non-stoichiometric compound Non-stoichiometric compounds are chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space ...
s, the proportions may be reproducible with regard to their preparation, and give fixed proportions of their component elements, but proportions that are not integral .g.,_for_palladium_hydride,_PdHx_(0.02_<_x_<_0.58).html" ;"title="palladium_hydride.html" ;"title=".g., for palladium hydride">.g., for palladium hydride, PdHx (0.02 < x < 0.58)">palladium_hydride.html" ;"title=".g., for palladium hydride">.g., for palladium hydride, PdHx (0.02 < x < 0.58)Phase diagram for Palladium-Hydrogen System
/ref> Chemical compounds have a unique and defined chemical structure held together in a defined spatial arrangement by
chemical bond A chemical bond is a lasting attraction between atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday ...
s. Chemical compounds can be
molecular A scanning tunneling microscopy image of pentacene molecules, which consist of linear chains of five carbon rings. A molecule is an electrically neutral group of two or more atom An atom is the smallest unit of ordinary matter In ...

molecular
compounds held together by
covalent bond A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs, and the stable balance of attractive and repulsive forces between atoms, when they s ...
s,
salts In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behavior and the changes they undergo during ...
held together by
ionic bond Ionic bonding is a type of chemical bond A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. The bond may result from the Coulomb's law, electrostatic force of attraction be ...
s,
intermetallic compounds An intermetallic (also called an intermetallic compound, intermetallic alloy, ordered intermetallic alloy, and a long-range-ordered alloy) is a type of metallic alloy An alloy is an admixture of metal A metal (from Ancient Greek, Gree ...
held together by
metallic bond Metallic bonding is a type of chemical bond A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. The bond may result from the Coulomb's law, electrostatic force of att ...
s, or the subset of chemical complexes that are held together by
coordinate covalent bondA coordinate covalent bond, also known as a dative bond, dipolar bond, or coordinate bond is a kind of two-center, two-electron covalent bond A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms. These ele ...
s. Pure
chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical elements cannot be broken down into simp ...
s are generally not considered chemical compounds, failing the two or more atom requirement, though they often consist of molecules composed of multiple atoms (such as in the
diatomic molecule Diatomic molecules are molecule File:Pentacene on Ni(111) STM.jpg, A scanning tunneling microscopy image of pentacene molecules, which consist of linear chains of five carbon rings. A molecule is an electrically neutral group of two or more ...
H2, or the polyatomic molecule S8, etc.). Many
chemical A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which ...

chemical
compounds have a unique numerical identifier assigned by the
Chemical Abstracts Service Chemical Abstracts Service (CAS) is a division of the American Chemical Society The American Chemical Society (ACS) is a scientific society A learned society (; also known as a learned academy, scholarly society, or academic association) i ...
(CAS): its
CAS number A CAS Registry Number, also referred to as CASRN or CAS Number, is a unique numerical identifier An identifier is a name that identifies (that is, labels the identity of) either a unique object or a unique ''class'' of objects, where the "object" ...
. There is varying and sometimes inconsistent nomenclature differentiating substances, which include truly non-stoichiometric examples, from chemical compounds, which require the fixed ratios. Many solid chemical substances—for example many
silicate mineral Silicate minerals are rock-forming mineral In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the solid Earth, the rock (geology) ...
s—are chemical substances, but do not have simple formulae reflecting chemically bonding of elements to one another in fixed ratios; even so, these
crystalline A crystal or crystalline solid is a solid Solid is one of the four fundamental states of matter (the others being liquid, gas and plasma). The molecules in a solid are closely packed together and contain the least amount of kinet ...

crystalline
substances are often called "
non-stoichiometric compound Non-stoichiometric compounds are chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space ...
s". It may be argued that they are related to, rather than being chemical compounds, insofar as the variability in their compositions is often due to either the presence of foreign elements trapped within the crystal structure of an otherwise known true ''chemical compound'', or due to perturbations in structure relative to the known compound that arise because of an excess of deficit of the constituent elements at places in its structure; such non-stoichiometric substances form most of the crust and
mantle Mantle may refer to: *Mantle (geology) A mantle is a layer inside a planetary body A planet is an astronomical body Astronomy (from el, ἀστρονομία, literally meaning the science that studies the laws of the stars) is a n ...
of the Earth. Other compounds regarded as chemically identical may have varying amounts of heavy or light
isotope Isotopes are two or more types of atoms that have the same atomic number 300px, The Rutherford–Bohr model of the hydrogen atom () or a hydrogen-like ion (). In this model it is an essential feature that the photon energy (or frequency) of ...
s of the constituent elements, which changes the ratio of elements by mass slightly.


Types


Molecules

A molecule is an
electrically Electricity is the set of physical phenomena associated with the presence and motion Image:Leaving Yongsan Station.jpg, 300px, Motion involves a change in position In physics, motion is the phenomenon in which an object changes its positio ...
neutral group of two or more atoms held together by chemical bonds. A molecule may be
homonuclear Homonuclear molecules, or homonuclear species, are molecules composed of only one Chemical element, element. Homonuclear molecules may consist of various numbers of atoms, depending on the element's properties. Some elements form molecules of more t ...
, that is, it consists of atoms of one chemical element, as with two atoms in the
oxygen Oxygen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same ...

oxygen
molecule (O2); or it may be
heteronuclear A heteronuclear molecule is a molecule File:Pentacene on Ni(111) STM.jpg, A scanning tunneling microscopy image of pentacene molecules, which consist of linear chains of five carbon rings. A molecule is an electrically neutral group of two or ...
, a chemical compound composed of more than one element, as with
water Water (chemical formula H2O) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known li ...
(two hydrogen atoms and one oxygen atom; H2O).


Ionic compounds

An ionic compound is a chemical compound composed of
ion An ion () is an atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ...
s held together by electrostatic forces termed
ionic bonding Ionic bonding is a type of chemical bond A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. The bond may result from the Coulomb's law, electrostatic force of attraction be ...

ionic bonding
. The compound is neutral overall, but consists of positively charged ions called
cation An ion () is an atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are u ...
s and negatively charged ions called
anion An ion () is an atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ...
s. These can be simple ions such as the
sodium Sodium is a with the  Na (from Latin ''natrium'') and  11. It is a soft, silvery-white, highly reactive . Sodium is an , being in of the periodic table. Its only stable is 23Na. The free metal does not occur in nature, and must be ...

sodium
(Na+) and
chloride The chloride ion An ion () is an atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects th ...

chloride
(Cl) in
sodium chloride Sodium chloride , commonly known as salt (although sea salt also contains other chemical salt (chemistry), salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With Molar mass, molar ...
, or polyatomic species such as the
ammonium The ammonium cation An ion () is an atom or molecule with a net electric charge, electrical charge. The charge of an electron is considered negative by convention and this charge is equal and opposite to charge of a proton, which is conside ...

ammonium
() and
carbonate In chemistry, a carbonate is a salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of Salt (chemistry), salts; salt in its natural form as a crystallinity, crystalline mi ...

carbonate
() ions in
ammonium carbonate Ammonium carbonate is a salt with the chemical formula (NH4)2CO3. Since it readily degrades to gaseous ammonia and carbon dioxide upon heating, it is used as a leavening agent and also as smelling salt. It is also known as baker's ammonia and wa ...

ammonium carbonate
. Individual ions within an ionic compound usually have multiple nearest neighbours, so are not considered to be part of molecules, but instead part of a continuous three-dimensional network, usually in a
crystalline structure In crystallography Crystallography is the experimental science of determining the arrangement of atoms in crystalline solids (see crystal structure). The word "crystallography" is derived from the Greek words ''crystallon'' "cold drop, frozen ...

crystalline structure
. Ionic compounds containing basic ions
hydroxide Hydroxide is a diatomic anion with chemical formula A chemical formula is a way of presenting information about the chemical proportions of atom An atom is the smallest unit of ordinary matter In classical physics and general che ...
(OH) or
oxide An oxide () is a chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) composed of atoms from more than one chemical element, element held together by che ...
(O2−) are classified as bases. Ionic compounds without these ions are also known as
salts In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behavior and the changes they undergo during ...
and can be formed by acid–base reactions. Ionic compounds can also be produced from their constituent ions by
evaporation Evaporation is a type of that occurs on the of a as it changes into the gas phase. The surrounding gas must not be saturated with the evaporating substance. When the molecules of the liquid collide, they transfer energy to each other bas ...

evaporation
of their
solvent A solvent (from the Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the ...

solvent
,
precipitation In meteorology Meteorology is a branch of the (which include and ), with a major focus on . The study of meteorology dates back , though significant progress in meteorology did not begin until the 18th century. The 19th century saw mod ...
,
freezing Freezing is a phase transition where a liquid turns into a solid when its temperature is lowered below its freezing point. In accordance with the internationally established definition, freezing means the solidification phase change of a liquid o ...

freezing
, a solid-state reaction, or the
electron transfer Electron transfer (ET) occurs when an electron The electron is a subatomic particle In physical sciences, subatomic particles are smaller than atom An atom is the smallest unit of ordinary matter In classical physics and genera ...
reaction of
reactive Reactive may refer to: *Generally, capable of having a reaction (disambiguation) *An adjective abbreviation denoting a Bowling ball#Coverstock technology, bowling ball coverstock made of reactive resin *Reactivity (chemistry) *Reactive mind *Reacti ...
metals with reactive non-metals, such as
halogen The halogens () are a group A group is a number A number is a mathematical object used to counting, count, measurement, measure, and nominal number, label. The original examples are the natural numbers 1, 2, 3, 4, and so forth. Numbers can b ...

halogen
gases. Ionic compounds typically have high
melting Melting, or Enthalpy of fusion, fusion, is a physical process that results in the phase transition of a chemical substance, substance from a solid to a liquid. This occurs when the internal energy of the solid increases, typically by the applic ...

melting
and
boiling point The boiling point of a substance is the temperature at which the vapor pressure 280px, The ''pistol test tube'' experiment. The tube contains alcohol and is closed with a piece of cork. By heating the alcohol, the vapors fill in the space, inc ...
s, and are hard and
brittle tensile testpieces A material is brittle if, when subjected to stress (physics), stress, it fracture Fracture is the separation of an object or material into two or more pieces under the action of stress. The fracture of a solid usually ...
. As solids they are almost always electrically insulating, but when or dissolved they become highly
conductive In physics Physics is the that studies , its , its and behavior through , and the related entities of and . "Physical science is that department of knowledge which relates to the order of nature, or, in other words, to the regular s ...
, because the ions are mobilized.


Intermetallic compounds

An intermetallic compound is a type of
metallic Metallic may be a reference to: *Metal A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts El ...

metallic
alloy An alloy is an admixture of metal A metal (from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in ...
that forms an ordered solid-state compound between two or more metallic elements. Intermetallics are generally hard and brittle, with good high-temperature mechanical properties. They can be classified as stoichiometric or nonstoichiometic intermetallic compounds.


Complexes

A coordination complex consists of a central atom or ion, which is usually
metal A metal (from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is appro ...

metal
lic and is called the ''coordination centre'', and a surrounding array of bound molecules or ions, that are in turn known as ''
ligand In coordination chemistry A coordination complex consists of a central atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by havi ...
s'' or complexing agents. Many metal-containing compounds, especially those of
transition metal In chemistry, the term transition metal (or transition element) has three possible definitions: * The IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations tha ...
s, are coordination complexes. A coordination complex whose centre is a metal atom is called a metal complex of d block element.


Bonding and forces

Compounds are held together through a variety of different types of bonding and forces. The differences in the types of bonds in compounds differ based on the types of elements present in the compound. London dispersion forces are the weakest force of all
intermolecular forces An intermolecular force (IMF) (or secondary force) is the force that mediates interaction between molecules, including the electromagnetic forces of attraction or repulsion which act between atoms and other types of neighboring particles, e.g. atom ...
. They are temporary attractive forces that form when the
electrons The electron is a subatomic particle In physical sciences, subatomic particles are smaller than atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has m ...
in two adjacent atoms are positioned so that they create a temporary
dipole In electromagnetism Electromagnetism is a branch of physics involving the study of the electromagnetic force, a type of physical interaction that occurs between electric charge, electrically charged particles. The electromagnetic force is c ...

dipole
. Additionally, London dispersion forces are responsible for condensing non polar substances to liquids, and to further freeze to a solid state dependent on how low the temperature of the environment is. A
covalent bond A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs, and the stable balance of attractive and repulsive forces between atoms, when they s ...
, also known as a molecular bond, involves the sharing of electrons between two atoms. Primarily, this type of bond occurs between elements that fall close to each other on the
periodic table of elements The periodic table, also known as the periodic table of elements, is a tabular display of the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry ...

periodic table of elements
, yet it is observed between some metals and nonmetals. This is due to the mechanism of this type of bond. Elements that fall close to each other on the periodic table tend to have similar
electronegativities Electronegativity, symbolized as '' χ'', is the tendency of an atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. ...

electronegativities
, which means they have a similar affinity for electrons. Since neither element has a stronger affinity to donate or gain electrons, it causes the elements to share electrons so both elements have a more stable
octet Octet may refer to: Music * Octet (music) In music, an octet is a musical ensemble consisting of eight Musical instrument, instruments or voices, or a musical composition written for such an ensemble. Octets in classical music Octets in Europea ...
.
Ionic bonding Ionic bonding is a type of chemical bond A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. The bond may result from the Coulomb's law, electrostatic force of attraction be ...

Ionic bonding
occurs when
valence electrons In chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they under ...
are completely transferred between elements. Opposite to covalent bonding, this chemical bond creates two oppositely charged ions. The metals in ionic bonding usually lose their valence electrons, becoming a positively charged
cation An ion () is an atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are u ...
. The nonmetal will gain the electrons from the metal, making the nonmetal a negatively charged
anion An ion () is an atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ...
. As outlined, ionic bonds occur between an electron donor, usually a metal, and an electron acceptor, which tends to be a nonmetal.
Hydrogen bonding A hydrogen bond (or H-bond) is a primarily Electrostatics, electrostatic force of attraction between a hydrogen Hydrogen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of ...
occurs when a
hydrogen atom A hydrogen atom is an atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touch ...

hydrogen atom
bonded to an electronegative atom forms an
electrostatic Electrostatics is a branch of physics Physics is the that studies , its , its and behavior through , and the related entities of and . "Physical science is that department of knowledge which relates to the order of nature, or, in oth ...
connection with another electronegative atom through interacting dipoles or charges.


Reactions

A compound can be converted to a different chemical composition by interaction with a second chemical compound via a
chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and t ...

chemical reaction
. In this process, bonds between atoms are broken in both of the interacting compounds, and then bonds are reformed so that new associations are made between atoms. Schematically, this reaction could be described as , where A, B, C, and D are each unique atoms; and AB, AD, CD, and CB are each unique compounds.


See also

*
Chemical structure A chemical structure determination includes a chemist A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a scientist A scientist is a person who conducts Scientific method, scientific re ...
*
IUPAC nomenclature The International Union of Pure and Applied Chemistry The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations that represents chemists in individual countries. It is a mem ...
*
Dictionary of chemical formulas This is a list of common chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) composed of atoms from more than one chemical element, element held together ...
* List of compounds


References


Further reading

* {{Authority control Chemistry