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Hydrogen atom (center) contains a single proton and a single electron. Removal of the electron gives a cation (left), whereas addition of an electron gives an anion (right). The hydrogen anion, with its loosely held two-electron cloud, has a larger radius than the neutral atom, which in turn is much larger than the bare proton of the cation. Hydrogen forms the only cation that has no electrons, but even cations that (unlike hydrogen) still retain one or more electrons are still smaller than the neutral atoms or molecules from which they are derived.

An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass ("go") between electrodes in a solution, when an electric field is applied. It is the transliteration of the Greek participle ἰόν, ión, "going".

An ion consisting of a single atom is an atomic or monatomic ion; if it consists of two or more atoms, it is a molecular or polyatomic ion.

Anions and cations[link]

An anion (−) ( /ˈæn.aɪ.ən/ AN-eye-ən), from the Greek word ἄνω (ánō), meaning "up", is an ion with more electrons than protons, giving it a net negative charge (since electrons are negatively charged and protons are positively charged).

A cation (+) ( /ˈkæt.aɪ.ən/ KAT-eye-ən), from the Greek word κατά (katá), meaning "down", is an ion with fewer electrons than protons, giving it a positive charge. Since the charge on a proton is equal in magnitude to the charge on an electron, the net charge on an ion is equal to the number of protons in the ion minus the number of electrons.

General[link]

History and discovery[link]

The word ion is the Greek ιον (going), the present participle of ιεναι, ienai, "to go". This term was introduced by English physicist and chemist Michael Faraday in 1834 for the then-unknown species that goes from one electrode to the other through an aqueous medium.^[1][2] Faraday did not know the nature of these species, but he knew that since metals dissolved into and entered solution at one electrode, and new metal came forth from solution at the other electrode, that some kind of substance moved through the solution in a current, conveying matter from one place to the other.

Faraday also introduced the words anion for a negatively charged ion, and cation for a positively charged one. In Faraday's nomenclature, cations were named because they were attracted to the cathode in a galvanic device and anions were named due to their attraction to the anode.

Characteristics[link]

Ions in their gas-like state are highly reactive, and do not occur in large amounts on Earth, except in flames, lightning, electrical sparks, and other plasmas. These gas-like ions rapidly interact with ions of opposite charge to give neutral molecules or ionic salts. Ions are also produced in the liquid or solid state when salts interact with solvents (for example, water) to produce "solvated ions," which are more stable, for reasons involving a combination of energy and entropy changes as the ions move away from each other to interact with the liquid. These stabilized species are more commonly found in the environment at low temperatures. A common example is the ions present in seawater, which are derived from the dissolved salts.

All ions are charged, which means that like all charged objects they are:

• attracted to opposite electric charges (positive to negative, and vice versa),
• repelled by like charges
• when moving, travel in trajectories that are deflected by a magnetic field.

Electrons, due to their smaller mass and thus larger space-filling properties as matter waves, determine the size of atoms and molecules that possess any electrons at all. Thus, anions (negatively charged ions) are larger than the parent molecule or atom, as the excess electron(s) repel each other, and add to the physical size of the ion, because its size is determined by its electron cloud. As such, in general, cations are smaller than the corresponding parent atom or molecule due to the smaller size of its electron cloud. One particular cation (that of hydrogen) contains no electrons, and thus is very much smaller than the parent hydrogen atom.

Natural occurrences[link]

Ions are ubiquitous in nature and are responsible for diverse phenomena from the luminescence of the Sun to the existence of the Earth's ionosphere. Atoms in their ionic state may have a different color from neutral atoms, and thus light absorption by metal ions gives the color of gemstones. In both inorganic and organic chemistry (including biochemistry), the interaction of water and ions is extremely important; an example is the energy that drives breakdown of ATP. The following sections describe contexts in which ions feature prominently; these are arranged in decreasing physical length-scale, from the astronomical to the microscopic.

Astronomical[link]

The remnant of "Tycho's Supernova", a huge ball of expanding plasma. The outer shell shown in blue is X-ray emission by high-speed electrons.

A collection of non-aqueous gas-like ions, or even a gas containing a proportion of charged particles, is called a plasma. Greater than 99.9% of visible matter in the Universe may be in the form of plasmas.^[3] These include our Sun and other stars and the space between planets, as well as the space in between stars. Plasmas are often called the fourth state of matter because their properties are substantially different from those of solids, liquids, and gases. Astrophysical plasmas predominantly contain a mixture of electrons and protons (ionized hydrogen).

Related technology[link]

Ions can be non-chemically prepared using various ion sources, usually involving high voltage or temperature. These are used in a multitude of devices such as mass spectrometers, optical emission spectrometers, particle accelerators, ion implanters, and ion engines.

As reactive charged particles, they are also used in air purification by disrupting microbes, and in household items such as smoke detectors.

As signaling and metabolism in organisms are controlled by a precise ionic gradient across membranes, the disruption of this gradient contributes to cell death. This is a common mechanism exploited by natural and artificial biocides, including the ion channels gramicidin and amphotericin (a fungicide).

Inorganic dissolved ions are a component of total dissolved solids, an indicator of water quality in the world.

Chemistry[link]

Notation[link]

Denoting the charged state[link]

Equivalent notations for an iron atom (Fe) that lost two electrons.

When writing the chemical formula for an ion, its net charge is written in superscript immediately after the chemical structure for the molecule/atom. The net charge is written with the magnitude before the sign; that is, a doubly charged cation is indicated as 2+ instead of +2. However, the magnitude of the charge is omitted for singly charged molecules/atoms; for example, the sodium cation is indicated as Na⁺ and not Na¹⁺.

An alternative (and acceptable) way of showing a molecule/atom with multiple charges is by drawing out the signs multiple times; this is often seen with transition metals. Chemists sometimes circle the sign; this is merely ornamental and does not alter the chemical meaning. All three representations of Fe²⁺ shown in the figure are, thus, equivalent.

Mixed Roman numerals and charge notations for the uranyl ion. The oxidation state of the metal is shown as superscripted Roman numerals, whereas the charge of the entire complex is shown by the angle symbol together with the magnitude and sign of the net charge.

Monatomic ions are sometimes also denoted with Roman numerals; for example, the Fe²⁺ example seen above is occasionally referred to as Fe(II) or Fe^II. The Roman numeral designates the formal oxidation state of an element, whereas the superscripted numerals denotes the net charge. The two notations are, therefore, exchangeable for monatomic ions, but the Roman numerals cannot be applied to polyatomic ions. However, it is possible to mix the notations for the individual metal center with a polyatomic complex, as shown by the uranyl ion example.

Sub-classes[link]

If an ion contains unpaired electrons, it is called a radical ion. Just like uncharged radicals, radical ions are very reactive. Polyatomic ions containing oxygen, such as carbonate and sulfate, are called oxyanions. Molecular ions that contain at least one carbon to hydrogen bond are called organic ions. If the charge in an organic ion is formally centered on a carbon, it is termed a carbocation (if positively charged) or carbanion (if negatively charged).

Formation[link]

Formation of monatomic ions[link]

Monatomic ions are formed by the addition of electrons to the valence shell of the atom, which is the outer-most electron shell in an atom, or the losing of electrons from this shell. The inner shells of an atom are filled with electrons that are tightly bound to the positively charged atomic nucleus, and so do not participate in this kind of chemical interaction. The process of gaining or losing electrons from a neutral atom or molecule is called ionization.

Atoms can be ionized by bombardment with radiation, but the more usual process of ionization encountered in chemistry is the transfer of electrons between atoms or molecules. This transfer is usually driven by the attaining of stable ("closed shell") electronic configurations. Atoms will gain or lose electrons depending on which action takes the least energy.

For example, a sodium atom, Na, has a single electron in its valence shell, surrounding 2 stable, filled inner shells of 2 and 8 electrons. Since these filled shells are very stable, a sodium atom tends to lose its extra electron and attain this stable configuration, becoming a sodium cation in the process

Na → Na⁺ + e−

On the other hand, a chlorine atom, Cl, has 7 electrons in its valence shell, which is one short of the stable, filled shell with 8 electrons. Thus, a chlorine atom tends to gain an extra electron and attain a stable 8-electron configuration, becoming a chloride anion in the process:

Cl + e−
→ Cl⁻

This driving force is what causes sodium and chlorine to undergo a chemical reaction, wherein the "extra" electron is transferred from sodium to chlorine, forming sodium cations and chloride anions. Being oppositely charged, these cations and anions form ionic bonds and combine to form sodium chloride, NaCl, more commonly known as rock salt.

Na⁺ + Cl⁻ → NaCl

Formation of polyatomic and molecular ions[link]

An electrostatic potential map of the nitrate ion (NO−
3). The 3-dimensional shell represents a single arbitrary isopotential.

Polyatomic and molecular ions are often formed by the gaining or losing of elemental ions such as H⁺ in neutral molecules. For example, when ammonia, NH₃, accepts a proton, H⁺, it forms the ammonium ion, NH+
4. Ammonia and ammonium have the same number of electrons in essentially the same electronic configuration, but ammonium has an extra proton that gives it a net positive charge.

Ammonia can also lose an electron to gain a positive charge, forming the ion ·NH+
3. However, this ion is unstable, because it has an incomplete valence shell around the nitrogen atom, making it a very reactive radical ion.

Due to the instability of radical ions, polyatomic and molecular ions are usually formed by gaining or losing elemental ions such as H⁺, rather than gaining or losing electrons. This allows the molecule to preserve its stable electronic configuration while acquiring an electrical charge.

Ionization potential[link]

The energy 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 orbitals is exhausted of electrons. For this reason, ions tend to form in ways that leave them with full orbital blocks. For example, sodium has one valence electron 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 has seven valence electrons, so in ionized form it is commonly found with one gained electron, as Cl⁻. Caesium has the lowest measured ionization energy of all the elements and helium has the greatest.^[4] In general, the ionization energy of metals is much lower than the ionization energy of nonmetals, which is why, in general, metals will lose electrons to form positively charged ions and nonmetals will gain electrons to form negatively charged ions.

Ionic bonding[link]

Ionic bonding is a kind of chemical bonding that arises from the mutual attraction of oppositely charged ions. Since ions of like charge repel each other, they do not usually exist on their own. Instead, many of them may form a crystal lattice, in which ions of opposite charge are bound to each other. The resulting compound is called an ionic compound, and is said to be held together by ionic bonding. In ionic compounds there arise characteristic distances between ion neighbors from which the spatial extension and the ionic radius of individual ions may be derived.

The most common type of ionic bonding is seen in compounds of metals and nonmetals (except noble gases, which rarely form chemical compounds). Metals are characterized by having a small number of electrons in excess of a stable, closed-shell electronic configuration. As such, they have the tendency to lose these extra electrons in order to attain a stable configuration. This property is known as electropositivity. Non-metals, on the other hand, are characterized by having an electron configuration just a few electrons short of a stable configuration. As such, they have the tendency to gain more electrons in order to achieve a stable configuration. This tendency is known as electronegativity. When a highly electropositive metal is combined with a highly electronegative nonmetal, the extra electrons from the metal atoms are transferred to the electron-deficient nonmetal atoms. This reaction produces metal cations and nonmetal anions, which are attracted to each other to form a salt.

Chemical applications[link]

This section requires expansion.

Gas-like ions and solvated ions both have tremendous impact on chemical analysis and synthesis.

Mass spectrometry[link]

Catalysis[link]

Transition metal ions catalysis[link]

This section is empty. You can help by adding to it.

Templated synthesis of organic compounds[link]

This section is empty. You can help by adding to it.

Common ions[link]

See also[link]

• Air ionizer
• Anode
• Cathode
• Ion beam
• Ion source
• Ionic radius
• Auroras
• List of plasma (physics) articles

References[link]

v t e Galvanic cells Non-rechargeable: primary cells Alkaline battery Aluminium battery Bunsen cell Chromic acid cell Clark cell Daniell cell Dry cell Grove cell Leclanché cell Lithium battery Mercury battery Nickel oxyhydroxide battery Silicon–air battery Silver-oxide battery Weston cell Zamboni pile Zinc–air battery Zinc–carbon battery Zinc–chloride battery Rechargeable: secondary cells Automotive battery Lead–acid battery Lead–acid battery (gel) Lithium–air battery Lithium-ion battery Beltway battery Lithium-ion polymer battery Lithium iron phosphate battery Lithium–sulfur battery Lithium–titanate battery Nickel–cadmium battery Nickel–hydrogen battery Nickel–iron battery Nickel–lithium battery Nickel–metal hydride battery Low self-discharge NiMH battery Nickel–zinc battery Potassium-ion battery Rechargeable alkaline battery Sodium-ion battery Sodium–sulfur battery Vanadium redox battery Zinc–bromine battery Zinc–cerium battery Kinds of cells Battery Wet cell Dry cell Concentration cell Flow battery Fuel cell Trough battery Voltaic pile Parts of cells Anode Catalyst Cathode Electrolyte Half-cell Ions Salt bridge Semipermeable membrane

Ali G
F2F
Portrayed by	Sacha Baron Cohen
Duration	1996–1997 (F2F) 1998–2000 (The Eleven O'Clock Show) 2000, 2003–04 (Da Ali G Show) 2002 (Ali G Indahouse)
First appearance	F2F
Created by	Sacha Baron Cohen
Profile
Occupation	Interviewer, Singer, Rapper, Junglist
Residence	Staines
Relationships Parents Tina (mother) Sibling(s) Rory Romances Julie (fiancee) Grandparents Nana Aunts and uncles Jamal Derrick

Ali G (born Alistair Leslie Graham) is a satirical fictional character created and performed by English comedian Sacha Baron Cohen. Originally appearing on Channel 4's Eleven O'Clock show, as the title character of Channel 4's Da Ali G Show in 2000 and on HBO in 2003–2004, he is also the title character of the film Ali G Indahouse. Cohen's character Ali G, along with Borat and Brüno, has been retired.^[1]

Development of the character[link]

The character of Ali G is a stereotype of a white suburban male from Staines (now Staines-upon-Thames) who imitates rap culture as well as urban British and Jamaican culture, particularly through hip hop, reggae, drum and bass and jungle music. Ali G was part of a group called Berkshire Massif, and he ran and grew up in an area of Slough called Langley (both actual locations in the UK). He also lived part of his life in Staines. Baron Cohen has stated that BBC Radio 1 DJ Tim Westwood was an influence on the development of the Ali G character – Westwood hosts Radio 1's Rap Show and speaks in a faux Multicultural London English and Hip-Hop dialect. Ali G's middle class credentials mirror Westwood's: the latter was brought up in Lowestoft, Suffolk as a bishop's son.^[2]

Prior to Ali G's appearance on The Eleven O'Clock Show, Baron Cohen had portrayed a similar character named MC Jocelyn Cheadle-Hume on a show he presented called F2F, which ran on a satellite channel called Talk TV (owned by Granada Television). While chatting to a group of skateboarders, in character, Baron Cohen realised that people could be led to believe the character was real, and filmed a number of segments which were ordered off air by London Weekend Television.^[2]

History and appearances[link]

Ali G, a boorish, uneducated, faux-streetwise poseur with a deeply stereotypical view of the world, first came to prominence on Channel 4's The Eleven O'Clock Show as the "voice of da yoof" in 1998.^[3] He interviewed various public figures in the United Kingdom, always either embarrassing his interviewee by displaying a mixture of uninformed political incorrectness, or getting the interview 'victim' to agree to some breathtaking inaccuracy or insult. His key saying is "booyakasha".

Other examples of his bold interviewing style include getting Lindsay Urwin, the Bishop of Horsham, to admit that God created the Universe, and then asked him, "And since then, [God]'s just chilled?" Ali G asked the Bishop about God's appearance, to which the Bishop replied, "Well, he's sort of Jesus-shaped." During an interview with James Ferman (former director of the British Board of Film Classification), Ali G asks whether his made-up vulgarities would restrict a film to an over-18 audience, and suggests that film censorship be performed by younger persons who understand contemporary slang. In a interview with the Chairman of the Arts Council of England Gerry Robinson Ali G first question was: "Why is it that everything you fund is so crap?"

Ali G was in a series of ads for the 2005–06 NBA season, in which he used his brand of off-kilter journalism to interview various NBA stars. The spots were directed by Spike Lee.

Ali G was also featured in the music video "Music" by Madonna as her limo driver.

Background[link]

Ali G is a fictional gang member of the "West Staines Massif", who currently lives with his grandmother in a semi-detached house at 36 Cherry Blossom Close, in the heart of the "Staines Ghetto". He was educated at what he calls "da Matthew Arnold Skool"; the Matthew Arnold School is a real secondary school. He also has a short stint at Vanguard College Preparatory School.

Staines, a working-class commuter town to the west of London, is far different from the inner city ghetto that Ali G claims. In the same comic vein, he also makes reference to other similar working-class towns in the area, such as Egham, Langley and Englefield Green. Despite the incongruous nature of his home town, he purports to exemplify inner city culture. Ali's "real" name is later revealed to be Alistair Leslie Graham (revealed in the eponymous film).

Ali G speaks a comical patois in keeping with his delusions of being black of Jamaican ancestry and peppered with such catchphrases as "Aight" (alright), "Booyakasha", "Big up Yaself", "Wagwaan", "West Side", "Batty Boy" "Respek" (respect), "For Real", "Poonani", "Check It" and "Keep It Real". His trademark hand gesture closely resembles the "dip snap".

Family[link]

Ali was born on a Council Estate to mother Tina. He has an older sister and an older brother. He has a younger sister and other younger siblings. When Ali was fifteen he went to live with his grandmother when his mother had another baby and there was no room for him and his older brother and sister, who went to live with their father. Ali's baby brothers are called Rory, Jamie and Guy.

Criticisms of the character[link]

Although Baron Cohen has repeatedly stated that the Ali G character is a parody of suburban, privileged youth 'acting black', numerous commentators have opined that the force of the humour is derived from stereotypes of blacks, not poser whites. According to this view of the character, the suburban background written into Ali G's character serves as a false alibi.^[4][5][6]

The comedian Felix Dexter has said that he appreciated the humour of an innocent confronting an expert with neither understanding the other, but that 'I feel that a lot of the humour is laughing at black street culture and it is being celebrated because it allows the liberal middle classes to laugh at that culture in a safe context where they can retain their sense of political correctness.^[7]

Notable people interviewed by Ali G[link]

• Edwin "Buzz" Aldrin, former astronaut, and the second man to walk on the moon. (Ali G also called him "Buzz Lightyear").
• Alex Alonso, author, professor and founder of Streetgangs.com
• David Beckham, football player and his wife Victoria Beckham, a member of the Spice Girls.
• Tony Benn, former British Labour MP, chairman and cabinet minister
• Boutros Boutros-Ghali,^[8] former Secretary General of the United Nations, mistakenly called 'Boutros Boutros Boutros Ghali by Ali-G. Boutros-Ghali clearly went so far as to participate in some of Ali G's notorious word games and providing the epilogue to the episode where, at Ali G's bidding, he tells youth viewers to 'enjoy the music of Bob Marley'. In response to Ali G's perceived ignorance, Boutros-Ghali provides a detailed explanation about why Disneyland is not represented in the United Nations, and reveals which foreign languages sound comical to his ear. The interview appeared on the War episode of the Da Ali G Show.^[9]
• Rhodes Boyson, former British Conservative education minister, who agreed with Ali G that metric system should not be taught in school because 'one deals in quarters and eighths of ounces'
• Pat Buchanan, American political commentator and former presidential candidate who began laughing uncontrollably when he realized he was being fooled
• Noam Chomsky, MIT professor and linguist
• Jarvis Cocker, Pulp singer
• Linda Cohn, ESPN anchor
• Gaz Coombes, Supergrass singer
• Paul Daniels, magician
• James X. Dempsey, privacy guru and Vice President for Public Policy at the Center for Democracy and Technology
• Sam Donaldson, veteran journalist
• Mohamed Al-Fayed, former owner of Harrods and current owner of Fulham FC
• Marlin Fitzwater, former White House Press Secretary, who ended the interview after calling Ali G an idiot.
• Jerome Friedman, MIT Professor of physics and 1990 Nobel Prize winner
• John Kenneth Galbraith, economist and public intellectual
• Daryl Gates, former Los Angeles Police Chief (He was referred to as "Bill Gates" by Ali G).
• Newt Gingrich, former Speaker of the United States House of Representatives
• John Gray, author of Men Are from Mars, Women Are from Venus
• Leanna Heart, adult film star
• Neil Hamilton, former Conservative politician
• Kent Hovind, evangelist and Young Earth creationist
• Glenn Hubbard, former professional baseball player
• Reed Irvine, founder of Accuracy in Media
• Jenna Jameson, adult film star
• Ernie Johnson, Jr., sports broadcaster
• Steve Kerr, former American professional basketball player who, according to Ali G, works on "TMT"; Kerr is a basketball analyst with U.S. cable network TNT.
• C. Everett Koop, former US Surgeon General
• James Lipton, host of Bravo's Inside the Actors Studio
• John McCain, United States Senator from Arizona and 2000/2008 Presidential Candidate
• Ralph Nader, consumer activist and former US presidential candidate for the Green Party
• Thomas J. Pickard, former FBI Director
• Gail Porter, television presenter
• Sue Ramsey, Irish politician, Sinn Féin
• Sally Jessy Raphaël, former talk show host, (who congratulated him for 'being himself')
• Andy Rooney, of the CBS programme 60 Minutes, who furiously ended his interview abruptly
• Charles Schultze, former Chief Economic Advisor to President Jimmy Carter^[10]
• Brent Scowcroft, former National Security Advisor and Air Force General
• Tomasz Starzewski, fashion designer
• Dick Thornburgh, former U.S. Attorney General
• Donald Trump, real estate developer, who walks off dismissively around one minute into the interview
• Stansfield Turner, former Director Central Intelligence Agency
• Lindsay Urwin, the Bishop of Horsham
• Gore Vidal, author and essayist, (whom Ali G mistook for Vidal Sassoon)
• Christine Todd Whitman, former New Jersey governor and United States Environmental Protection Agency‎ administrator
• Kobe Bryant, NBA basketball player (whom he asks about the number of springs in a basketball)
• Sammy Wilson, Northern Irish politician, Democratic Unionist Party
• Naomi Wolf, author and feminist
• Professional basketball players Steve Nash (who was an award winning player "MP3" according to Ali G and unable to speak proper English being Canadian), Ben Wallace (who he accuses of "playa-hating"), Shaquille O'Neal (who he argued with about the meaning of the NBA, Ali thinking it stood for Nationwide Basketball Society), Tim Duncan (who he tried to get a pair of free sneakers from), Robert Horry, Dwyane Wade (who he didn't realise was an NBA player, claiming he had snuck in to "hang with mah man Shaquille O'Neal"), Richard Jefferson (whom he called Thomas Jefferson his son), Charles Barkley, Kenny Smith and Reggie Miller

References[link]

External links[link]

Listen to this article (info/dl)

This audio file was created from a revision of the "Ali G" article dated 2006-04-28, and does not reflect subsequent edits to the article. (Audio help)

More spoken articles

• Channel 4 Ali G website
• Sacha Baron Cohen interview with NPR's Robert Siegel
• An article in the Guardian
• Tricked into Silly interview with Ali G, Alex Alonso, Streetgangs.com, March 12, 2002