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An ion is an atom
Atom

|-! bgcolor=gray | Properties|-||}The atom is a basic unit of matter consisting of a dense, central atomic nucleus surrounded by a electron cloud of electric charge electrons....
 or molecule
Molecule

In chemistry, a molecule is defined as a sufficiently stable, electric charge neutral group of at least two atoms in a definite arrangement held together by very strong chemical bonds....
 which has lost or gained one or more electron
Electron

The electron is a subatomic particle that carries a negative electric charge. It has elementary particle and is believed to be a point particle....
s, giving it a positive or negative electrical charge. According to the Model of Bohr
Bohr model

In atomic physics, the Bohr model created by Niels Bohr depicts the atom as a small, positively charged atomic nucleus surrounded by electrons that travel in circular orbits around the nucleus—similar in structure to the solar system, but with electrostatic forces providing attraction, rather than gravity....
 this will be from or in the outer shield 'n'. A negatively charged ion, which has more electron
Electron

The electron is a subatomic particle that carries a negative electric charge. It has elementary particle and is believed to be a point particle....
s than it has proton
Proton

The proton is a subatomic particle with an electric charge of +1 elementary charge. It is found in the nucleus of each atom but is also stable by itself and has a second identity as the hydrogen ion, H+....
s, is known as an anion (??? ana: Greek 'up') (; an-eye-on).






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Encyclopedia


Nitrate Ion Elpot
An ion is an atom
Atom

|-! bgcolor=gray | Properties|-||}The atom is a basic unit of matter consisting of a dense, central atomic nucleus surrounded by a electron cloud of electric charge electrons....
 or molecule
Molecule

In chemistry, a molecule is defined as a sufficiently stable, electric charge neutral group of at least two atoms in a definite arrangement held together by very strong chemical bonds....
 which has lost or gained one or more electron
Electron

The electron is a subatomic particle that carries a negative electric charge. It has elementary particle and is believed to be a point particle....
s, giving it a positive or negative electrical charge. According to the Model of Bohr
Bohr model

In atomic physics, the Bohr model created by Niels Bohr depicts the atom as a small, positively charged atomic nucleus surrounded by electrons that travel in circular orbits around the nucleus—similar in structure to the solar system, but with electrostatic forces providing attraction, rather than gravity....
 this will be from or in the outer shield 'n'. A negatively charged ion, which has more electron
Electron

The electron is a subatomic particle that carries a negative electric charge. It has elementary particle and is believed to be a point particle....
s than it has proton
Proton

The proton is a subatomic particle with an electric charge of +1 elementary charge. It is found in the nucleus of each atom but is also stable by itself and has a second identity as the hydrogen ion, H+....
s, is known as an anion (??? ana: Greek 'up') (; an-eye-on). Conversely, a positively-charged ion, which has fewer electrons than protons, is known as a cation (?at? kata: Greek 'down') (; cat-eye-on).

An ion consisting of a single atom is called a monatomic ion
Monatomic ion

A monatomic ion is an ion consisting of many ions of the same atoms. A type I binary ionic compound contains a metal that forms only one type of ion....
, but if it consists of two or more atoms, it is a polyatomic ion
Polyatomic ion

A polyatomic ion, also known as a molecular ion, is a charged species composed of two or more atoms Covalent bond or of a complex that can be considered as acting as a single unit in the context of acid and Base chemistry or in the formation of salt ....
. Polyatomic ions containing oxygen
Oxygen

Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]...
, such as carbonate
Carbonate

In chemistry, a carbonate is a salt or ester of carbonic acid....
 and sulfate
Sulfate

In inorganic chemistry, a sulfate is a salt of sulfuric acid....
, are called oxyanion
Oxyanion

An oxyanion or oxoanion is a chemical compound with the generic formula AxOyz-. . Oxyanions are formed by a large majority of the chemical elements....
s.

Ions are denoted in the same way as electrically neutral atoms and molecules except for the presence of a superscript indicating the sign of the net electric charge and the number of electrons lost or gained, if more than one. For example: H
Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the chemical symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly combustion and explosive Diatomic molecule gas with the molecular formula H2....
+ and SO
Sulfur oxide

Sulphur oxide refers to one or more of the following:* Lower sulphur oxides * Sulphur monoxide * Sulphur dioxide * Sulphur trioxide *Higher sulphur oxides ...
42-.

Formation


Formation of polyatomic and molecular ions

Polyatomic and molecular ions are often formed by the combination of elemental ions such as H+ with neutral molecules or by the gain of such elemental ions from neutral molecules. A simple example of this is the ammonium ion NH4+ which can be formed by ammonia NH3 accepting a proton, H+. Ammonia and ammonium have the same number of electrons in essentially the same electronic configuration but differ in protons. The charge has been added by the addition of a proton (H+) not the addition or removal of electrons. The distinction between this and the removal of an electron from the whole molecule is important in large systems because it usually results in much more stable ions with complete electron shells. For example NH3·+ is not stable because of an incomplete valence shell around nitrogen and is in fact a radical
Radical (chemistry)

In chemistry, radicals are atoms, molecules or ions with unpaired electrons on an otherwise open shell configuration. These unpaired electrons are usually highly chemical reaction, so radicals are likely to take part in chemical reactions....
 ion.

Ionization potential

The energy
Energy

In physics, energy is a scalar physical quantity that describes the amount of Work_ that can be performed by a force. Energy is an attribute of objects and systems that is subject to a conservation law....
 required to detach an electron in its lowest energy state from an atom or molecule of a gas with less net electric charge is called the ionization potential, or ionization energy. The nth ionization energy of an atom is the energy required to detach its nth electron after the first n - 1 electrons have already been detached.

Each successive ionization energy is markedly greater than the last. Particularly great increases occur after any given block of atomic orbital
Atomic orbital

An atomic orbital is a mathematical function that describes the wave-like behavior of an electron in an atom. This function can be used to calculate the probability of finding any electron of an atom in any specific region around the atom's nucleus....
s is exhausted of electrons. For this reason, ions tend to form in ways that leave them with full orbital blocks. For example, sodium
Sodium

Sodium is an element which has the symbol Na , atomic number 11, atomic mass 23 amu , and a common oxidation number +1. Sodium is a soft, silvery white, highly reactive element and is a member of the alkali metals within "group 1" ....
 has one valence electron
Valence electron

In science, valence electrons are the electrons contained in the outermost, or valence, electron shell of an atom. Valence electrons are important in determining how an chemical element reacts chemically with other elements: The fewer valence electrons an atom holds, the less reactivity it becomes and the more likely it is to chemical rea...
, in its outermost shell, so in ionized form it is commonly found with one lost electron, as Na+. On the other side of the periodic table, chlorine
Chlorine

Chlorine...
 has seven valence electrons, so in ionized form it is commonly found with one gained electron, as Cl-. Francium
Francium

Francium , formerly known as Mendeleev's predicted elements-caesium and actinium K, is a chemical element that has the symbol Fr and atomic number 87....
 has the lowest ionization energy of all the elements and fluorine
Fluorine

Fluorine is the chemical element with the symbol F and atomic number 9. Fluorine forms a single bond with itself in elemental form, resulting in the diatomic F2 molecule....
 has the greatest. The ionization energy of metals is generally much lower than the ionization energy of nonmetals, which is why metals will generally lose electrons to form positively-charged ions while nonmetals will generally gain electrons to form negatively-charged ions

A neutral atom contains an equal number of Z protons in the nucleus and Z electrons in the electron shell. The electrons' negative charges thus exactly cancel the protons' positive charges. In the simple view of the Free electron model
Free electron model

In solid-state physics, the free electron model is a simple model for the behaviour of valence electrons in a crystal structure of a metallic solid....
, a passing electron is therefore not attracted to a neutral atom and cannot bind to it. In reality, however, the atomic electrons form a cloud into which the additional electron penetrates, thus being exposed to a net positive charge part of the time. Furthermore, the additional charge displaces the original electrons and all of the Z + 1 electrons rearrange into a new configuration.

Ions


  • Anions are negatively charged ions, formed when an atom gains electrons in a reaction. Anions are negatively charged because there are more electrons associated with them than there are protons in their nuclei.


  • Cations are positively charged ions, formed when an atom loses electrons in a reaction, forming an 'electron hole
    Electron hole

    An electron hole is the conceptual and mathematical opposite of an electron, useful in the study of physics and chemistry. The concept describes the lack of an electron....
    '. Cations are the opposite of anions, since cations have fewer electrons than protons.


  • Radicals or radical ions
    Radical (chemistry)

    In chemistry, radicals are atoms, molecules or ions with unpaired electrons on an otherwise open shell configuration. These unpaired electrons are usually highly chemical reaction, so radicals are likely to take part in chemical reactions....
     are atom groups that contain unpaired electrons and are highly reactive.


Plasma

A collection of non-aqueous
Aqueous solution

An aqueous solution is a solution in which the solvent is water. It is usually shown in chemical equations by appending to the relevant formula....
 gas-like ions, or even a gas containing a proportion of charged particles, is called a plasma, often called the fourth state of matter because its properties are quite different from solid
Solid

A solid object is in the states of matter characterized by resistance to deformation and changes of volume. In other words, it has high values both of Young's modulus and of shear modulus; this contrasts e.g....
s, liquid
Liquid

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 its bulk material....
s, and gas
Gas

In physics, a gas is a state of matter, consisting of a collection of particles without a definite shape or volume that are in more or less random motion....
es. Astrophysical plasmas containing predominantly a mixture of electrons and protons, may make up as much as 99.9% of visible matter in the universe.

Applications

Ions are essential to life
Life

Life is a characteristic of organisms that exhibit certain biological processes such as chemical reactions or other events that results in a transformation....
. Sodium
Sodium

Sodium is an element which has the symbol Na , atomic number 11, atomic mass 23 amu , and a common oxidation number +1. Sodium is a soft, silvery white, highly reactive element and is a member of the alkali metals within "group 1" ....
, potassium
Potassium

Potassium is a chemical element. It has the symbol K , atomic number 19, and atomic mass 39.0983. Potassium was first isolated from potash, hence the name....
, calcium
Calcium

Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft grey alkaline earth metal, and is the fifth most abundant element by mass in the earth's Crust ....
 and other ions play an important role in the cell
Cell (biology)

The cell is the structural and functional unit of all known Life organisms. It is the smallest unit of an organism that is classified as living, and is often called the building bricks of life....
s of living organisms, particularly in cell membrane
Cell membrane

The cell membrane is the interface between the cellular machinery inside the cell and the fluid outside.It is a semipermeable lipid bilayer found in all cell ....
s. They have many practical, everyday applications in items such as smoke detector
Smoke detector

A smoke detector is a device that detects smoke and issues a signal to a fire alarm system, or issues a local audible and/or visual alarm from the detector itself....
s, and are also finding use in unconventional technologies such as ion engines. Inorganic dissolved ions are a component of total dissolved solids
Total dissolved solids

Total Dissolved Solids is an expression for the combined content of all inorganic and organic compound substances contained in a liquid which are present in a molecular, ionized or micro-granular suspended form....
, an indicator of water quality
Water quality

Water quality is the physical, chemical and biological characteristics of water. It is most frequently used by reference to a set of standards against which compliance can be assessed....
 in the world.

Common ions

Common Cations
Common NameFormulaHistoric Name
Simple Cations
AluminiumAl3+alumen
BariumBa2+Baryta
BerylliumBe2+beryl
CadmiumCd2+cadmia
CaesiumCs+caesius
CalciumCa2+calx
Chromium(II)Cr2+Chromous
Chromium(III)Cr3+Chromic
Chromium(VI)Cr6+Chromyl
Cobalt(II)Co2+Cobaltous
Cobalt(III)Co3+Cobaltic
Copper(I)Cu+Cuprous
Copper(II)Cu2+Cupric
Copper(III)Cu3+cuprum
Gallium Ga3+Gallia
Gold (I) Au+ 
Gold (III)Au3+ 
HeliumHe2+(Alpha particle)
HydrogenH+(Proton)
Iron(II)Fe2+Ferrous
Iron(III)Fe3+Ferric
Lead(II)Pb2+Plumbous
Lead(IV)Pb4+Plumbic
LithiumLi+lithos
MagnesiumMg2+Magnesia
Manganese(II)Mn2+Manganous
Manganese(III)Mn3+Manganic
Manganese(IV)Mn4+ 
Manganese(VII)Mn7+ 
Mercury(II)Hg2+Mercuric
Nickel(II)Ni2+Nickelous
Nickel(III)Ni3+Nickelic
Potassium K+potash
SilverAg+siolfur
SodiumNa+soda
StrontiumSr2+Strontian
Thallium (I)Tl+ 
Thallium (III)Tl3+ 
Tin(II)Sn2+Stannous
Tin(IV)Sn4+Stannic
ZincZn2+zink
Polyatomic Cations
AmmoniumNH4+ 
HydroniumH3O+ 
NitroniumNO2+ 
UranylUO22+ 
VanadylVO2+ 
Mercury(I)Hg22+Mercurous
Common Anions
Formal NameFormulaAlt. Name
Simple Anions
ArsenideAs3- 
AzideN3- 
BromideBr- 
ChlorideCl- 
FluorideF- 
HydrideH- 
IodideI- 
NitrideN3- 
OxideO2- 
PhosphideP3- 
SulfideS2- 
PeroxideO22- 
Oxoanions
ArsenateAsO43- 
ArseniteAsO33- 
BorateBO33- 
BromateBrO3- 
HypobromiteBrO- 
CarbonateCO32- 
Hydrogen carbonateHCO3-Bicarbonate
HydroxideOH- 
ChlorateClO3- 
PerchlorateClO4- 
ChloriteClO2- 
HypochloriteClO- 
ChromateCrO42- 
DichromateCr2O72- 
IodateIO3- 
NitrateNO3- 
NitriteNO2- 
PhosphatePO43- 
Hydrogen phosphateHPO42- 
Dihydrogen phosphateH2PO4- 
PermanganateMnO4- 
PhosphitePO33- 
SulfateSO42- 
ThiosulfateS2O32- 
Hydrogen sulfateHSO4-Bisulfate
SulfiteSO32- 
Hydrogen sulfiteHSO3-Bisulfite
Anions from Organic Acids
AcetateC2H3O2- 
FormateHCO2- 
OxalateC2O42- 
Hydrogen oxalateHC2O4-Binoxalate
Other Anions
hydrosulfideHS-Bisulfide
TellurideTe2- 
AmideNH2- 
CyanateOCN- 
ThiocyanateSCN- 
CyanideCN- 


See also

  • Air ionizer
  • Cathode
    Cathode

    A cathode is an electrode through which electric charge flows out of a polarized electrical device. Mnemonic: CCD .From an electrochemical point of view, positively charged ion invariably move toward the cathode and/or negatively charged ion move away from it to balance the electrons arriving from external circuitry....
  • Anode
    Anode

    An anode is an electrode through which electric charge flows into a polarized electrical device. Mnemonic: ACID . Electrons flow in the opposite direction to the positive electric current....


External links

  • Department of Education, Newfoundland and Labrador-Canada "'". A Periodic table reporting ionic charges for every chemical element.