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Inorganic Nomenclature

Inorganic nomenclature

The IUPAC nomenclature of inorganic chemistry is a systematic way of naming inorganic chemical compounds as recommended by the International Union of Pure and Applied Chemistry (IUPAC). Ideally, every inorganic compound should have a name from which an unambiguous formula can be determined. There is also a IUPAC nomenclature of organic chemistry. The names "caffeine" and "3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione" both describe the same chemical. The systematic name encodes the structure and composition of the caffeine molecule in some detail, and provides an unambiguous reference to this compound, whereas the name "caffeine" just names it. These advantages make the systematic name far superior to the common name when absolute clarity and precision is required. However, even professional chemists will use the non-systematic name almost all of the time, because caffeine is a well-known common chemical with a unique structure. Similarly, the chemical water is always known as such, never as "dihydrogen monoxide." # Single atom anions are named with an -ide suffix: for example, H^- is hydride. # Compounds with a positive ion (cation), the name of the compound is simply the cation's name (usually the same as the element's), followed by the anion. For example, NaCl is sodium chloride, and CaF₂ is calcium fluoride. # Cations able to take on more than one positive charge are labeled with Roman numerals in parentheses. For example, Cu⁺ is copper(I), Cu²⁺ is copper(II). An older, deprecated notation is to append -ous or -ic to the root of the Latin name to name ions with a lesser or greater charge. Under this naming convention, Cu⁺ is cuprous and Cu²⁺ is cupric. For naming metal complexes see the page on complex (chemistry). # Oxyanions (polyatomic anions containing oxygen) are named with -ite or -ate, for a lesser or greater quantity of oxygen. For example, NO₂^- is nitrite, while NO₃^- is nitrate. If four oxyanions are possible, the prefixes hypo- and per- are used: Hypochlorite is ClO^-, Perchlorate is ClO₄^-, # The prefix bi- is a deprecated way of indicating the presence of a single hydrogen ion, as in "sodium bicarbonate" (NaHCO₃). The modern method specifically names the hydrogen atom. Thus, NaHCO₃ would be pronounced "sodium hydrogen carbonate". Positively charged ions are called cations and negatively charged ions are called anions. The cation is always named first. Ions can be metals or polyatomic ions. Therefore the name of the metal or positive polyatomic ion is followed by the name of the non-metal or negative polyatomic ion. The positive ion retains its element name whereas for a single non-metal anion the ending is changed to -ide. Example: sodium chloride, potassium oxide, or calcium carbonate. When the metal has more than one possible ionic charge or oxidation number the name becomes ambiguous. In these cases the oxidation number of the metal ion is represented by a Roman numeral in parentheses immediately following the metal ion name. For example in uranium(VI) fluoride the oxidation number of uranium is 6. Another example is the iron oxides. FeO is iron(II) oxide and Fe₂O₃ is iron(III) oxide. An older system used prefixes and suffixes to indicate the oxidation number, according to the following scheme:

Oxidation state	Cations and acids	Anions
Lowest	hypo- -ous	hypo- -ite
	-ous	-ite
	-ic	-ate
Highest	per- -ic	per- -ate

Thus the four oxyacids of chlorine are called hypochlorous acid (HOCl), chlorous acid (HOClO), chloric acid (HOClO₂) and perchloric acid (HOClO₃), and their respective conjugate bases are the hypochlorite, chlorite, chlorate and perchlorate ions. This system has partially fallen out of use, but survives in the common names of many chemical compounds: the modern literature contains few references to "ferric chloride" (instead calling it "iron(III) chloride"), but names like "potassium permanganate" (instead of "potassium manganate(VII)") and "sulfuric acid" abound.

Naming simple ionic compounds

An ionic compound is named by its cation followed by its anion. See polyatomic ions for a list of possible ions. For cations that take on multiple charges, the charge is written using Roman numerals in parentheses immediately following the element name) For example, Cu(NO₃)₂ is copper(II) nitrate, because the charge of two nitrate ions is 2 x -1 = -2, and since the net charge of the ionic compound must be zero, the Cu ion has a 2+ charge. This compound is therefore copper(II) nitrate. The Roman numerals in fact show the oxidation number, but in simple ionic compounds (i.e., not metal complexes) this will always equal the ionic charge on the metal. For a simple overview see [http://www.cofc.edu/~deavorj/101/nomenclature.html], for more details see [http://www2.potsdam.edu/walkerma/inorg_naming.pdf selected pages from IUPAC rules for naming inorganic compounds].

List of common ion names

Monatomic anions: :Cl^- chloride :S^2- sulfide :P^3- phosphide Polyatomic ions: :NH₄⁺ ammonium :H₃O⁺ hydronium :NO₃^- nitrate :NO₂^- nitrite :ClO^- hypochlorite :ClO₂^- chlorite :ClO₃^- chlorate :ClO₄^- perchlorate :SO₃^2- sulfite :SO₄^2- sulfate :HSO₃^- hydrogen sulfite (or bisulfate) :HCO₃^- hydrogen carbonate (or bicarbonate) :CO₃^2- carbonate :PO₄^3- phosphate :HPO₄^2- hydrogen phosphate :H₂PO₄^- dihydrogen phosphate :CrO₄^2- chromate :Cr₂O₇^2- dichromate :BO₃^3- orthoborate :AsO₄^3- arsenate :C₂O₄^2- oxalate :CN^- cyanide :MnO₄^- permanganate

Naming hydrates

Hydrates are ionic compounds that have absorbed water. They are named as the ionic compound followed by a numerical prefix and -hydrate. The numerical prefixes used are listed below: # mono- # di- # tri- # tetra- # penta- # hexa- # hepta- # octa- # nona- # deca- For example, CuSO₄ · 5H₂O is "copper(II) sulfate pentahydrate".

Naming molecular compounds

Inorganic molecular compounds are named with a prefix (see list above) before each element. The more electronegative element is written last and with an -ide suffix. For example, CO₂ is carbon dioxide, and CCl₄ is carbon tetrachloride. There are some exceptions to the rule, however. The prefix mono- is not used with the first element; for example, CO₂ is carbon dioxide, not "monocarbon dioxide". Sometimes prefixes are shortened when the ending vowel of the prefix "conflicts" with a starting vowel in the compound. This makes the compound easier to speak; for example, CO is "carbon monoxide" (as opposed to "monooxide").

Naming acids

Acids are named by the anion they form when dissolved in water. If an acid forms an anion named ___ide, it is named hydro___ic acid. For example, hydrochloric acid forms a chloride anion. Secondly, anions with an -ate suffix are formed from acids with an -ic suffix are dissolved -- chloric acid dissociates to chlorate anions in water. Thirdly, anions with an -ite suffix are formed when acids with an -ous suffix are dissolved in water; for example chlorous acid disassociates into chlorite anions.

Compositional nomenclature

Substitutive nomenclature

References

# Nomenclature of Inorganic Chemistry, Recommendations 1990, Oxford:Blackwell Scientific Publications. (1990)

External links

- [http://www.iupac.org/reports/provisional/abstract04/connelly_310804.html IUPAC Provisional Recommendations for the Nomenclature of Inorganic Chemistry (2004)] (online draft of an updated version of the "Red Book")
- [http://www.chem.qmul.ac.uk/iupac/bibliog/inorg.html Bibliography of IUPAC Recommendations on Inorganic Nomenclature] (last updated 2004-02-17)
- [http://dbhs.wvusd.k12.ca.us/webdocs/Nomenclature/Nomenclature.html ChemTeam Highschool Tutorial]
- [http://www2.potsdam.edu/walkerma/inorg_naming.pdf PDF file SUNY Potsdam.edu]
- [http://www.miramar.sdccd.cc.ca.us/faculty/fgarces/ChemComon/Tutorial/ChemNomen/ChemNomenclature.htm Nomenclature Tutorial] Category:Chemical nomenclature Category:Inorganic chemistry

Systematic name

There are millions of possible objects that can be described in science, too many to create common names for every one. As a response, a number of systems of systematic names have been created. These can be as simple as assigning a prefix and a number to each object (in which case they are a sort of catalog reference), or as complex as encoding the complete structure of the object in the name. Many systems combine some information about the named object with an extra sequence number to make it into a unique identifier.
- Systematic names for chemical elements and chemical compounds (administered by the IUPAC)
- Systematic names for biological organisms, initiated by Carolus Linnaeus: see scientific classification and binomial name
- Systematic names for asteroids, comets, stars and other astronomical objects (administered by the International Astronomical Union)
- Systematic names for genes, proteins, and other objects of molecular biology Systematic names often co-exist with earlier common names assigned before the creation of any systematic naming system. For example, many common chemicals are still referred to by their common names, even by chemists.

External links

- [http://www.acdlabs.co.uk/iupac/nomenclature/93/r93_125.htm Naming organic compounds]
- [http://www2.potsdam.edu/walkerma/inorg_naming.pdf Selected pages from IUPAC rules for naming inorganic compounds] Category:Naming conventions

Chemical compound

A chemical compound is a chemical substance formed from two or more elements, with a fixed ratio determining the composition. For example, dihydrogen monoxide (water, ₂) is a compound composed of two hydrogen atoms for every oxygen atom. In general, this fixed ratio must be fixed due to some sort of physical property, rather than an arbitrary man-made selection. This is why materials such as brass, the superconductor YBCO, the semiconductor aluminium gallium arsenide, or chocolate are considered mixtures or alloys rather than compounds. A defining characteristic of a compound is that it has a chemical formula. Formulas describe the ratio of atoms in a substance, and the number of atoms in a single molecule of the substance (thus the formula for ethene is ₂₄ rather than ₂). The formula does not indicate that a compound is composed of molecules; for example, sodium chloride (table salt, ) is an ionic compound. Compounds may have a number of possible phases. Most compounds can exist as solids. Molecular compounds may also exist as liquids or gases. All compounds will decompose to smaller compounds or individual atoms if heated to a certain temperature (called the decomposition temperature). Every chemical compound that has been described in the literature carries a unique numerical identifier, its CAS number.

Types of compounds

- Acids
- Bases
- Ionic compounds
- Salts
- Oxides
- Organic compounds

International Union of Pure and Applied Chemistry

The International Union of Pure and Applied Chemistry (IUPAC) is an international non-governmental organization devoted to the advancement of chemistry. It has as its members national chemistry societies. It is most well known as the recognized authority in developing standards for the naming of the chemical elements and their compounds, through its Interdivisional Committee on Nomenclature and Symbols (IUPAC nomenclature). It is a member of the International Council for Science (ICSU). In addition to nomenclature guidelines, the IUPAC sets standards for international spelling in the event of a dispute; for example, it ruled that aluminium is preferable to the American aluminum and sulfur rather than the British sulphur.

External link

- [http://www.iupac.org/ Official website]
- [http://www.acdlabs.com/download/name.html ACD/ChemSKetch] Freeware allowing generation of IUPAC Names (free version is limited to small structures) Category:Chemistry societies Category:Standards organizations Category:Chemical nomenclature ja:国際純正・応用化学連合

Inorganic compound

An inorganic compound is a chemical compound not containing carbon and hydrogen atoms bonded to each other.

Organic and inorganic

Although the number of inorganic compounds is huge, it is indeed overshadowed by the number of organic compounds — compounds which contain carbon and hydrogen bonded to each other, which comprise the vast majority of all compounds known. The science of chemistry is broadly divided into the two specialized fields of organic amd inorganic chemistry which focus respectively on organic and inorganic compounds.

Inorganic compounds and living organisms

In the past it was believed that organic compounds are found only in organisms, and this was how the initial distinction between the two groups had been made. Today, however, we know that this is far from true: thousands of organic compounds were synthetically formed; they don't come from and don't exist in organisms: drugs and plastics, for example. At the same time, many inorganic compounds exist in organisms, and are essential to life: sodium chloride (common salt), carbonic acid, phosphate ions and many more. The study of metal compounds in living systems is called bioinorganic chemistry.

Inorganic Carbon compounds

Carbon compounds are sometimes erroneously considered to be all organic; many compounds that contain carbon, however, are defined as strictly inorganic: carbon monoxide, carbon dioxide, carbonates, to name but a few. All these compounds have no hydrogen atoms bonded to the carbon.

Types of inorganic compounds

Major branches of inorganic compound groups include:
- Minerals, such as salt, asbestos, silicates, ...
- Metals and their alloys, like iron, copper, aluminium, brass, bronze, ...
- Compounds involving non-metallic elements, like silicon, phosphorus, chlorine, oxygen, for example water
- Metal complexes

Inorganic Chemistry

The field within which inorganic compounds are researched is called inorganic chemistry. Inorganic chemistry is divided into further branches based upon the type of materials and compounds being studied. The fields of organic and inorganic chemistry overlap in many cases particularly in organometallic chemistry.

Chemical formula

A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. It identifies each type of chemical element by its element symbol and identifies the number of atoms of such element to be found in each discrete molecule of that compound. The number of atoms (if greater than one) is indicated as a subscript. For non-molecular substances the subscripts indicate the ratio of elements in the empirical formula. Chemical formula used for a series of compounds that differ from each other by a constant unit is called general formula. Such a series is called the homologous series, while its members are called homologs.

Elements

In organic chemistry most compounds consist of the following five chemical elements:
- C carbon
- H hydrogen
- N nitrogen
- O oxygen
- S sulfur For other element symbols see list of elements by symbol.

Molecular and structural formulas

For example methane, a simple molecule consisting of one carbon atom bonded to four hydrogen atoms has the chemical formula: : CH₄ and glucose with six carbon atoms, twelve hydrogen atoms and six oxygen atoms has the chemical formula: : C₆H₁₂O₆. A chemical formula may also supply information about the types and spatial arrangement of bonds in the chemical, though it does not necessarily specify the exact isomer. For example ethane consists of two carbon atoms single-bonded to each other, each having three hydrogen atoms bonded to it. Its chemical formula can be rendered as CH₃CH₃. If there were a double bond between the carbon atoms (and thus each carbon only had two hydrogens), the chemical formula may be written: CH₂CH₂, and the fact that there is a double bond between the carbons is assumed. However, a more explicit and correct method is to write H₂C:CH₂ or H₂C=CH₂. The two dots or lines indicate that a double bond connects the atoms on either side of them. A triple bond may be expressed with three dots or lines, and if there may be ambiguity, a single dot or line may be used to indicate a single bond. Molecules with multiple functional groups that are the same may be expressed in the following way: (CH₃)₃CH. However, this implies a different structure from other molecules that can be formed using the same atoms (isomers). The formula (CH₃)₃CH implies a chain of three carbon atoms, with the middle carbon atom bonded to another carbon: Carbon chain and the remaining bonds on the carbons all leading to hydrogen atoms. However, the same number of atoms (10 hydrogens and 4 carbons, or C₄H₁₀) may be used to make a straight chain: CH₃CH₂CH₂CH₃. The alkene 2-butene has two isomers which the chemical formula CH₃CH=CHCH₃ does not identify. The relative position of the two methyl groups must be indicated by additional notation denoting whether the methyl groups are on the same side of the double bond (cis or Z) or on the opposite sides from each other.(trans or E)

Polymers

For polymers, parentheses are placed around the repeating unit. For example, a hydrocarbon molecule that is described as: CH₃(CH₂)₅₀CH₃, is a molecule with 50 repeating units. If the number of repeating units is unknown or variable, the letter n may be used to indicate this: CH₃(CH₂)_nCH₃.

Ions

For ions, the charge on a particular atom may be denoted with a right-hand superscript. For example Na⁺, or Cu²⁺. The total charge on a charged molecule or a polyatomic ion may also be shown in this way. For example: hydronium, H₃O⁺ or sulfate, SO₄^2-.

Isotopes

Although isotopes are more relevant to nuclear chemistry or stable isotope chemistry than to conventional chemistry, different isotopes may be indicated with a left-hand superscript in a chemical formula. For example, the phosphate ion containing radioactive phosphorus-32 is ³²PO₄^3-. Also a study involving stable isotope ratios might include ¹⁸O:¹⁶O. A left-hand subscript is sometimes used to indicate redundantly, for convenience, the atomic number.

Empirical formula

In chemistry, the empirical formula of a chemical is a simple expression of the relative number of each type of atom or ratio of the elements in it. Empirical formulas are the standard for ionic compounds, such as CaCl₂, and for macromolecules, such as SiO₂. An empirical formula makes no reference to isomerism, structure, or absolute number of atoms. The term empirical refers to the process of elemental analysis, a technique of analytical chemistry used to determine the relative percent composition of a pure chemical substance by element. For example, hexane could have a chemical formula of CH₃CH₂CH₂CH₂CH₂CH₃, implying that it has a straight chain structure, 6 carbon atoms, and 14 hydrogen atoms. However the empirical formula for the same molecule would be C₃H₇.

IUPAC nomenclature of organic chemistry

The IUPAC nomenclature of organic chemistry is a systematic way of naming organic chemical compounds as recommended by the International Union of Pure and Applied Chemistry (IUPAC). Ideally, every organic compound should have a name from which an unambiguous structural formula can be drawn. There is also a IUPAC nomenclature of inorganic chemistry. In IUPAC nomenclature, a number of prefixes, suffixes and infixes are used to describe the type and position of functional groups in the compound. For many compounds, naming can begin by determining the name of the parent hydrocarbon and by identifying any functional groups in the molecule that distinguish it from the parent hydrocarbon. The numbering of the parent alkane is used, as modified, if necessary, by application of the Cahn Ingold Prelog priority rules in the case that ambiguity remains after consideration of the structure of the parent hydrocarbon alone. The name of the parent hydrocarbon is modified by the application of the highest-priority functional group suffix, with the remaining functional groups indicated by numbered prefixes, appearing in the name in alphabetical order from first to last. In many cases, lack of rigor in applying all such nomenclature rules still yields a name that is intelligible — the aim, of course, being to avoid any ambiguity in terms of what substance is being discussed. For instance, strict application of CIP priority to the naming of the compound NH₂CH₂CH₂OH would render the name as 2-aminoethanol, which is preferred. However, the name 2-hydroxyethanamine unambiguously refers to the same compound. How the name was constructed: #There are two carbons in the main chain; this gives the root name "eth". #Since the carbons are singly-bonded, the suffix begins with "an". #The two functional groups are an alcohol (OH) and an amine (NH₂). The alcohol has the higher atomic number, and takes priority over the amine. The suffix for an alcohol ends in "ol", so that the suffix is "anol". #The amine group is not on the carbon with the OH (the #1 carbon), but one carbon over (the #2 carbon); therefore we indicate its presence with the prefix "2-amino". #Putting together the prefix, the root and the suffix, we get "2-aminoethanol". There is also an older naming system for organic compounds known as common nomenclature, which is often used for simple, well-known compounds, and also for complex compounds whose IUPAC names are too complex for everyday use. Simplified molecular input line entry specification (SMILES) strings are commonly used to describe organic compounds, and as such are a form of 'naming' them.

Alkanes

Straight-chain alkanes take the suffix "-ane" and are prefixed depending on the number of carbon atoms in the chain, as given by the following table: For example, the simplest alkane is CH₄ methane, and the nine-carbon alkane CH₃(CH₂)₇CH₃ is named nonane. Cyclic alkanes are simply prefixed with "cyclo-", for example C₄H₈ is cyclobutane and C₆H₁₂ is cyclohexane.

Iupac-alkane-1.png Iupac-alkane-2.png

Branched alkanes are named as a straight-chain alkane with attached alkyl groups. They are prefixed with a number indicating the carbon the group is attached to, counting from the end of the alkane chain. Infixed is the name of the substituent, as for alkanes in the table above, plus "-yl". For example, (CH₃)₂CHCH₃, commonly known as isobutane, is treated as a propane chain with a methyl group bonded to the middle (2) carbon, and given the systematic name 2-methylpropane. Numbers may be dropped when there is no ambiguity, so 2-methylpropane is just methylpropane. (1-methylpropane would be identical to butane.) If there is ambiguity in the position of the substituent, depending on which end of the alkane chain is counted as "1", then numbering is chosen so that the smallest number is used. For example, (CH₃)₂CHCH₂CH₃ (isopentane) is named 2-methylbutane, not 3-methylbutane. Since this resolves the ambiguity, the number is again dropped in this case.
alkyl If there are multiple side-branches of the same size alkyl group, their positions are separated by commas and the group prefixed with di-, tri-, tetra-, etc., depending on the number of branches (e.g. C(CH₃)₄ 2,2-dimethylpropane). If there are different groups, they are added in alphabetical order, separated by commas or hyphens: 3-ethyl-4-methylhexane. The longest possible main alkane chain is used; therefore 3-ethyl-4-methylhexane instead of 2,3-diethylpentane, even though these describe equivalent structures. The di-, tri- etc. prefixes are ignored for the purpose of alphabetical ordering of side chains (e.g. 3-ethyl-2,4-dimethylpentane, not 2,4-dimethyl-3-ethylpentane). If multiple chains of the longest possible length exist, the chain that has a larger number of branch points is the chain that is used.

Iupac-alkane-4.png

Subsidiary branches off a side-chain are prefixed according to a secondary numbering system specific to that side branch, numbering from the point of attachment to the main chain, and then the whole side-branch is parenthesised and treated as a single substituent. For example, 4-(1-methylethyl)octane is a octane chain with a side chain bonded to the 4th carbon, the side chain consisting of an ethyl group with a methyl group attached to the carbon closest to the main chain.

Alkenes and Alkynes

Alkyne Alkenes are named for their parent alkane chain with the suffix "-ene" and an infixed number indicating the position of the double-bonded carbon in the chain: CH₂=CHCH₂CH₃ is but-1-ene. Ethene (ethylene) and propene (propylene) do not require infixed numbers, since there is no ambiguity in the structures. As before, the lowest number is used. Multiple double bonds take the form -diene, -triene, etc., with the size prefix of the chain taking an extra "a": CH₂=CHCH=CH₂ is buta-1,3-diene. Simple cis and trans isomers are indicated with a prefixed cis- or trans-: cis-but-2-ene, trans-but-2-ene. More complex geometric isomerisations are described using the Cahn Ingold Prelog priority rules. Cahn Ingold Prelog priority rules Alkynes are named using the same system, with the suffix "-yne" indicating a triple bond: ethyne (acetylene), propyne (methylacetylene).

Alcohols

Alcohol Alcohols (R-OH) drop the terminal "e" from the name of the parent alkane, and take the suffix "-ol" with an infix numerical bonding position: CH₃CH₂CH₂OH is propan-1-ol. (Methanol and ethanol are unambiguous and do not require position numbers). The suffixes -diol, -triol, -tetraol, etc., are used for multiple -OH groups: Ethylene glycol CH₂OHCH₂OH is ethane-1,2-diol. Ethylene glycol If higher precedence functional groups are present (see order of precedence, below), the prefix "hydroxy" is used with the bonding position: CH₃CHOHCOOH is 2-hydroxypropanoic acid.

Halogenated compounds

Ethylene glycol Halogen functional groups are prefixed with the bonding position and take the form fluoro-, chloro-, bromo-, iodo-, etc., depending on the halogen. Multiple groups are dichloro-, trichloro-, etc, and disimilar groups are orded alphabetically as before. For example, CHCl₃ (chloroform) is trichloromethane. The anesthetic Halothane (CF₃CHBrCl) is 2-bromo-2-chloro-1,1,1-trifluoroethane.

Ketones

Ketone In general ketones (R-CO-R) take the suffix "-one" (pronounced own, not won) with an infix position number: CH₃CH₂CH₂COCH₃ is pentan-2-one. For common ketones some traditional names such as acetone and benzophenone predominate, and these are [http://www.acdlabs.com/iupac/nomenclature/93/r93_701.htm acceptable IUPAC names], although some introductory chemistry texts use alternative names for acetone such as propan-2-one or propanone (see diagram). If a higher precedence suffix is in use, the prefix "oxo-" is used: CH₃CH₂CH₂COCH₂CHO is 3-oxohexanal.

Aldehydes

Aldehyde Aldehydes (R-CHO) take the suffix "-al". Since they are always at the end of a alkane chain, they do not need a position number: HCHO (formaldehyde) is methanal, CH₃CHO (acetaldehyde) is ethanal. If other functional groups are present, the chain is numbered such that the aldehyde carbon is in the "1" position. If a prefix form is required, "oxo-" is used (as for ketones), with the position number indicating the end of a chain: CHOCH₃COOH is 3-oxopropanoic acid. If the carbon in the carbonyl group cannot be included in the attached chain (for instance in the case of cyclic aldehydes), the prefix "formyl-" or the suffix "-carbaldehyde" is used: C₆H₁₁CHO is cyclohexanecarbaldehyde.

Carboxylic acids

Carboxylic acid In general carboxylic acids are named with the suffix "-anoic acid". As for aldehydes, they take the "1" position on the parent chain, but do not have their position number indicated. For example, CH₃CH₂CH₂CH₂COOH (valeric acid) is named pentanoic acid. For common carboxylic acids some traditional names such as acetic acid are in such widespread use they are considered [http://www.acdlabs.co.uk/iupac/nomenclature/93/r93_705.htm retained IUPAC names], although "systematic" names such as ethanoic acid are also acceptable. For carboxylic acids attached to a benzene ring such as Ph-COOH, these are named as benzoic acid or its derivatives. If there are multiple carboxyl groups on the same parent chain, the suffix "-carboxylic acid" can be used (as -dicarboxylic acid, -tricarboxylic acid, etc.). In these cases, the carbon in the carboxyl group does not count as being part of the main alkane chain. The same is true for the prefix form, "carboxyl-". Citric acid is one example; it is named 2-hydroxy-1,2,3-propanetricarboxylic acid, rather than 2-carboxy, 2-hydroxypentanedioic acid.

Ethers

Ether Ethers (R-O-R) consist of an oxygen atom between the two attached carbon chains. The shorter of the two chains becomes the first part of the name with the -ane suffix changed to -oxy, and the longer alkane chain become the suffix of the name of the ether. Thus CH₃OCH₃ is methoxymethane, and CH₃OCH₂CH₃ is methoxyethane (not ethoxymethane). If the oxygen is not attached to the end of the main alkane chain, then the whole shorter alkyl-plus-ether group is treated as a side-chain and prefixed with its bonding position on the main chain. Thus CH₃OCH(CH₃)₂ is 2-methoxypropane.

Esters

Ester Esters (R-CO-O-R') are named as alkyl derivatives of carboxylic acids. The alkyl (R') group is named first. The R-CO-O part is then named as a separate word based on the carboxylic acid name, with the ending changed from oic acid to oate. For example, CH₃CH₂CH₂CH₂COOCH₃ is methyl pentanoate, and (CH₃)₂CHCH₂CH₂COOCH₂CH₃ is ethyl 4-methylpentanoate. For esters such as ethyl acetate (CH₃COOCH₂CH₃), ethyl formate (HCOOCH₂CH₃) or dimethyl phthalate that are based on common acids, IUPAC recommends use of these established names, called [http://www.acdlabs.co.uk/iupac/nomenclature/93/r93_511.htm retained names]. Some simple examples, named both ways, are shown in the figure above. ethyl formate If the alkyl group is not attached at the end of the chain, the bond position to the ester group is infixed before "-yl": CH₃CH₂CH(CH₃)OOCCH₂CH₃ may be called but-2-yl propanoate or but-2-yl propionate.

Amines and Amides

Amide Amines (R-NH₂) are named for the attached alkane chain with the suffix "-amine" (e.g. CH₃NH₂ methanamine). If necessary, the bonding position is infixed: CH₃CH₂CH₂NH₂ propan-1-amine, CH₃CHNH₂CH₃ propan-2-amine. The prefix form is "amino-". For secondary amines (of the form R-NH-R), the longest carbon chain attached to the nitrogen atom becomes the primary name of the amine; the other chain is prefixed as an alkyl group with location prefix given as an italic N: CH₃NHCH₂CH₃ is N-methylethanamine. Tertiary amines (R-NR-R) are treated similarly: CH₃CH2₂N(CH₃)CH₂CH₂CH₃ is N-methyl-N-ethylpropanamine. Amide Amides (R-CO-NH₂) take the suffix "-amide". There is no prefix form, and no location number is required since they always terminate a carbon chain, e.g. CH₃CONH₂ (acetamide) is named ethanamide. Secondary and tertiary amides are treated similarly to the case of amines: alkane chains bonded to the nitrogen atom are treated as substituents with the location prefix N: HCON(CH₃)₂ is N,N-dimethylmethanamide.

Cyclic compounds

acetamide Cycloalkanes and aromatic compounds can be treated as the main parent chain of the compound, in which case the position of substituents are numbered around the ring structure. For example, the three isomers of xylene CH₃C₆H₄CH₃, commonly the ortho-, meta-, and para- forms, are 1,2-dimethylbenzene, 1,3-dimethylbenzene, and 1,4-dimethylbenzene. The cyclic structures can also be treated as functional groups themselves, in which case they take the prefix "cycloalkyl-" (e.g. "cyclohexyl-") or for benzene, "phenyl-". The IUPAC nomenclature scheme becomes rapidly more elaborate for more complex cyclic structures, with notation for compounds containing conjoined rings, and many common names such as phenol, furan, indole, etc. being accepted as base names for compounds derived from them.

Order of precedence of groups

When compounds contain more than one functional group, the order of precedence determines which groups are named with prefix or suffix forms. The highest precedence group takes the suffix, with all others taking the prefix form. However, double and triple bonds only take suffix form (-en and -yn) and are used with other suffixes. Prefixed substituents are ordered alphabetically (excluding any modifiers such as di-, tri-, etc.), e.g. chlorofluoromethane, not fluorochloromethane. If there are multiple functional groups of the same type, either prefixed or suffixed, the position numbers are ordered numerically (thus ethane-1,2-diol, not ethane-2,1-diol.) The N position indicator for amines and amides comes before "1", e.g. CH₃CH(CH₃)CH₂NH(CH₃) is N,2-dimethylpropanamine.
- Note: These suffixes, in which the carbon atom is counted as part of the preceding chain, are the most commonly used. See individual functional group articles for more details.

Common nomenclature

Common nomenclature is an older system of naming organic compounds.

Ketones

Common names for ketones can be derived by naming the two alkyl or aryl groups bonded to the carbonyl group as separate words followed by the word ketone.
- Acetone
- Acetophenone
- Benzophenone
- Ethyl isopropyl ketone
- Diethyl ketone The first three of the names shown above are still considered to be [http://www.acdlabs.com/iupac/nomenclature/93/r93_701.htm acceptable IUPAC names].

Aldehydes

The common name for an aldehyde is derived from the common name of the corresponding carboxylic acid by dropping the word acid and changing the suffix from -ic or -oic to -aldehyde.
- Formaldehyde
- Acetaldehyde

Ions

The IUPAC nomenclature also provides rules for naming ions.

Hydron

Hydron is a generic term for hydrogen cation; protons, deuterons and tritons are all hydrons.

Parent hydride cations

Simple cations formed by adding a hydron to a hydride of a halogen, chalcogen or nitrogen-family element are named by adding the suffix "-onium" to the element's root: H₄N⁺ is ammonium, H₃O⁺ is oxonium, and H₂F⁺ is fluoronium. Ammonium was adopted instead of nitronium, which commonly refers to NO₂⁺. If the cationic center of the hydride is not a halogen, chalcogen or nitrogen-family element then the suffix "-ium" is added to the name of the neutral hydride after dropping any final 'e'. H₅C⁺ is methanium, HO-O⁺H₂ is dioxidanium (HO-OH is dioxidane), and H₂N-N⁺H₃ is diazanium (H₂N-NH₂ is diazane).

Cations and substitution

The above cations except for methanium are not, strictly speaking, organic, since they do not contain carbon. However, many organic cations are obtained by substituting another element or some functional group for a hydrogen. The name of each substitution is prepended to the hydride cation name. If many substitutions by the same functional group occur, then the number is indicated by prepending "di-", "tri-" as with halogenation. (CH₃)₃O⁺ is trimethyloxonium. CH₃F₃N⁺ is trifluoromethylammonium.

References

# Nomenclature of Organic Chemistry, Oxford:Pergamon Press, 1979; A Guide to IUPAC Nomenclature of Organic Compounds, Recommendations 1993, Oxford:Blackwell Scientific Publications, 1993.

External links

- [http://www.acdlabs.com/iupac/nomenclature/ IUPAC Nomenclature of Organic Chemistry] (online version of the "Blue Book")
- [http://www.chem.qmul.ac.uk/iupac/ IUPAC Recommendations on Organic & Biochemical Nomenclature, Symbols, Terminology, etc.] (includes IUBMB Recommendations for biochemistry)
- [http://www.chem.qmul.ac.uk/iupac/bibliog/cnoc.html Bibliography of IUPAC Recommendations on Organic Nomenclature] (last updated 2003-04-11) Category:Chemical nomenclature Category:Organic chemistry Category:Encodings ja:IUPAC命名法

Caffeine

Caffeine, also known as trimethylxanthine, coffeine, theine, mateine, guaranine, methyltheobromine and 1,3,7-trimethylxanthine, is a xanthine alkaloid found naturally in such foods as coffee beans, tea, kola nuts, Yerba mate, guarana berries, and (in small amounts) cacao beans and Yaupon Holly. For the plant, caffeine acts as a natural pesticide since it paralyzes and kills some of the insects that attempt to feed on the plant. Caffeine-containing beverages, such as coffee, enjoy great popularity. Additionally, it is occasionally used medically in the formulation of some analgesics. Caffeine's main pharmacological properties are: a stimulant action on the central nervous system with psychotropic effects and stimulation of respiration, a stimulation of the heart rate, and a mild diuretic effect.

Chemical properties

Caffeine is an alkaloid of the methylxanthine family, which also includes the similar compounds theophylline and theobromine. In its pure state it is an intensely bitter white powder. Its chemical formula is C₈H₁₀N₄O₂, its systematic name is 1,3,7-trimethyl xanthine or 3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione, and its structure is shown above. Its International Chemical Identifier is InChI=1/C8H10N4O2/c1-10-4-9-6-5(10)7(13)12(3)8(14)11(6)2/h4H,1-3H3.

Physical properties

Pure caffeine occurs as odorless, white, fleecy masses, glistening needles or powder.
- Melting point: 238 °C
- Boiling point: 178 °C (sublimes)
- Density: 1.2 g/cm³
- Volatility: 0.5%
- Vapor pressure: 101 kPa @ 178 °C
- pH: 6.9 (1% solution)
- Solubility in water: 2.17%
- Vapor density: 6.7 g/m³
- Molecular weight: 194.19 g/mol

Caffeine extraction

It is very difficult to know the exact amount of caffeine in a particular drink that is not automatically prepared. The amount of caffeine in a single serving of coffee varies considerably due to many variables. Concentration can vary from bean to bean within a given bush; preparation of the raw bean will affect concentration, as well as multiple variables involved in brewing. To extract caffeine takes some time (about two hours) and requires chemicals unavailable for everyday use and a nice system of distillation and sublimation. To extract caffeine, one must take the beverage one wants to extract the caffeine from and mix it with a solvent with a finer affiliation to the caffeine and a different density. Chloroform is known to possess both these properties. Caffeine will go in the solvent it is the most soluble in, and it is more soluble in chloroform than water. Using a separating funnel, one should take about 30 ml of chloroform and 200 ml of the beverage one wants to extract the caffeine from and agitate for about two minutes. The bottom phase will be the chloroform and the caffeine, so one will keep this phase. Repeating this step about five times should ensure extraction of most of the caffeine. The next step is a distillation using a standard distillation column where one gets rid of most of the chloroform. Finally, one has to sublimate the caffeine under vacuum. If the result is a fine white powder, one's extraction has succeeded.

Sources

One common source of caffeine is the coffee plant, the beans of which are used to make coffee. Caffeine content varies substantially between Arabica and Robusta species and to a lesser degree between varieties of each species. One 'shot' of coffee contains about 40 mg of caffeine. Thus, a "double shot" espresso contains about 80 mg. A single serving (6 fl oz / 150 ml) of strong drip coffee or one-half caffeine tablet would deliver about 100 mg. However, there is a large variation in the amount of caffeine per serve, ranging from about 40 mg to 120 mg. Such variability was shown to be even higher in a study conducted in 2005 by Ben Desbrow, a dietitian of Griffith University. His survey of 99 short blacks found caffeine content ranging from 25 mg to 214 mg. Generally, dark roast coffee has less caffeine than lighter roasts since the roasting process reduces caffeine content of the bean. Tea is another common source of caffeine in many cultures. Tea contains somewhat less caffeine per serving than coffee, (usually about half as much, depending on the strength of the brew), though certain types of tea, such as black and oolong, contain more caffeine. Caffeine is also common in soft drinks such as cola. Such drinks typically contain about 15 mg to 40 mg of caffeine per serving. Most energy drinks such as Red Bull contain 80 mg. Mateine and guaranine are other names for caffeine. The names come from yerba maté and guarana respectively, caffeine-containing plants used for tea and other things. Many yerba maté enthusiasts insist that mateine is a stereoisomer of caffeine and thus a different substance altogether. However, this is impossible; caffeine is an achiral molecule with no stereogenic centers (also known as a chiral centers), and therefore has no stereoisomers. Similar claims are sometimes made of guaranine. Caffeine is sometimes called theine when it is found in tea, as the caffeine in tea was once thought to be a separate compound to the caffeine found in coffee. But tea does contain another xanthine, theophylline whose chemical formula is C₇H₈N₄O₂ compared to caffeine's C₈H₁₀N₄O₂.

Coffee

All fluid ounces are U.S. fluid ounces.
- Coffee, brewed (drip) - 4 to 20 mg/floz (130 to 680 mg/litre) (20 to 100 mg/5 floz)
- Coffee, decaffeinated - 0.4 to 0.6 mg/floz (13 to 20 mg/litre)
- Coffee, instant - 4 to 12 mg/floz (130 to 400 mg/litre)
- Espresso Arabica - ~40 mg/floz (1.36 g/litre)
- Espresso Robusta - ~100 mg/floz (3.4 g/litre)

Teas and other infusions

- Black tea, brewed (USA) - 2.5 to 11 mg/floz (85 to 370 mg per litre)
- Black tea, brewed (other) - 3 to 14 mg/floz (100 to 470 mg/litre)
- Black tea, canned iced - 2 to 3 mg/floz (70 to 100 mg/litre)
- Black tea, instant - 3.5 mg/floz (120 mg/litre)
- Oolong, 3.75 mg/floz (120 mg per litre) (12 to 55 mg per tea bag, i.e. one serving)
- Green tea, 2.5 mg/floz (85 mg/litre) (8 to 30 mg per tea bag, i.e. one serving)
- White tea, 2.0 mg/floz (68 mg/litre) (6 to 25 mg per tea bag, i.e. one serving)
- Decaf, 0.5 mg/oz (17 mg/litre) (1 to 4 mg per tea bag, i.e. one serving)
- Tisanes (i.e. Herbal teas) - caffeine content depends on the herb, e.g. Chamomile and Rooibos "teas" have no caffeine while Yerba mate and Guarana do contain varying quantities. Many tea drinkers characterise herbal tea simply as that which, unlike black or green tea, contains no caffeine.

Chocolate

Chocolate is a weak stimulant due to content of theobromine, theophylline, and caffeine.[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15549276] However, chocolate contains too little of these compounds for a reasonable serving to create effects in humans that are on par with coffee.

Other sources

- Energy drink - 10 mg/floz (340 mg/litre). Some countries limit the caffeine content at 135 mg/litre.
- Soft drink (caffeinated) - 3 to 8 mg/floz (100 to 270 mg/litre, some countries limit the caffeine content in cola drinks to 200 mg/l)
- Pill (caffeine) - 200 mg (100 mg in Canada and many countries within EU)
- Buckfast Tonic Wine - 375 mg/litre (0.05% of caffeine by weight)
- Jolt Gum - 45 mg/piece
- Bawls - 67mg per 10oz, 80 per 12oz

Equivalents to 200 mg of caffeine

- One caffeine pill (Two in some countries where these are 100 mg)
- ~2 shots of espresso from robusta beans (2 floz)
- ~2 "5 floz containers" of regular coffee (10 floz)
- ~1.3 L soft drink (these can vary widely in content)
- ~5 cups (8 floz) of black tea or ~10 cups (8 floz) of green tea
- ~5 cans of soda (these can vary widely in content) In the European Union, a warning must be placed on packaging if the caffeine content of any beverage exceeds 150 mg per litre. This includes caffeine from any source (including guarana, which is often found in energy drinks). In many countries, caffeine is classified as a flavouring.

History

Although tea consumption in China began thousands of years ago, the first documented use of caffeine in a beverage for its pharmacological effect was by the sufis of Yemen, who used coffee to stay awake during prayers in the 15th century. In the 16th century there were coffeehouses in Cairo and Mecca. Coffeehouses opened in Europe in the 17th century. Caffeine was isolated by the German chemist Friedrich Ferdinand Runge in 1819. According to the legend, he did this at the instigation of Johann Wolfgang von Goethe (Weinberg & Bealer 2001).

Mechanism of Action

Caffeine is thought to act by blocking adenosine receptors on the surface of cells. This thereby blocks a pathway leading to breakdown of cyclic adenosine monophosphate (cAMP). The usual effect of adenosine in nerve cells is to inhibit nerve conduction by inhibiting post-synaptic potentials. The caffeine molecule, being structurally similar to adenosine, binds to the same receptors but does not stimulate them, thereby decreasing the adenosine action. The resulting increased nerve activity causes the release of the hormone epinephrine (adrenaline), which in turn leads to several effects such as higher heart rate, increased blood pressure, increased blood flow to muscles, decreased blood flow to the skin and inner organs, and release of glucose by the liver. It also increases the levels of the neurotransmitter dopamine in the brain, similar to amphetamines. Other purported mechanisms of action of caffeine include mobilisation of intracellular calcium and inhibition of specific phosphodiesterases, however these only occur at high non-physiological concentrations.

Metabolism and toxicology

Caffeine is completely absorbed from the stomach and small intestine, within 45 minutes of ingestion. It is widely distributed in total body water and is eliminated by apparent first-order kinetics that can be described by a one-compartment open-model system. Caffeine is metabolized in the liver by the cytochrome P-450 enzyme system. The first metabolic products of caffeine are three dimethylxanthines: paraxanthine (84%), theobromine (12%) and theophylline (4%). Paraxanthine increases lipolysis, leading to elevated glycerol and free fatty acid levels in the blood plasma. Theobromine, the principal alkaloid in cocoa (chocolate), can dilate blood vessels and increase urine volume. Theophylline relaxes smooth muscles of the bronchi and is used to treat asthma. However, the therapeutic dose is many time greater than the levels achieved from caffeine metabolism. Each of these metabolites is further metabolised and then excreted in the urine. Caffeine is quickly and completely removed from the brain, and, unlike other CNS stimulants or alcohol, its effects are short-lived. In many people, caffeine does not negatively affect concentration or higher mental functions, and hence caffeinated drinks are often consumed in the course of work. Continued consumption of caffeine can lead to tolerance. Upon withdrawal, the body becomes oversensitive to adenosine, causing the blood pressure to drop dramatically, leading to headache and other symptoms. Any accumulated sleep debt will be fully felt on withdrawal as well. Intravenous caffeine (in the form of caffeine benzoate 500 mg over 1 hour) is occasionally used medically to treat post-lumbar puncture ("spinal tap") headache[http://www.emedicine.com/neuro/topic557.htm]. Although caffeine solutions are often used as a chemical standard for bitterness, caffeine is added to some soft drinks such as colas, Irn-Bru and Mountain Dew ostensibly for its taste. Mountain Dew While safe for humans, caffeine and its related compounds theobromine and theophylline are considerably more toxic to some other animals such as dogs, horses and parrots due to a much poorer ability to metabolize these compounds. Caffeine does more damage to spiders than most drugs.

Toxicity

Too much caffeine can lead to caffeine intoxication. The symptoms of this disorder are restlessness, nervousness, excitement, insomnia, flushed face, diuresis, gastrointestinal complaints, even hallucinations. They can occur in some people after as little as 250 mg per day. More than 1,000 mg per day may result in muscle twitching, rambling flow of thought and speech, cardiac arrhythmia or tachycardia, and psychomotor agitation. Caffeine intoxication can lead to symptoms similar to those of panic disorder and generalized anxiety disorder. The minimum lethal dose ever reported is 3,200 mg, intravenously. The LD₅₀ of caffeine is estimated between 13 and 19 grams for oral administration for an average adult. The LD₅₀ of caffeine is dependent on weight and estimated to be about 150 to 200 mg per kg of body mass, roughly 140 to 180 cups of coffee for an average adult taken within a limited timeframe that is dependent on half-life. The half-life, or time it takes for the amount of caffeine in the blood to decrease by 50%, ranges from 3.5 to 10 hours. In adults the half-life is generally around 5 hours. However contraceptive pills increase this to around 12 hours, and, for women over 3 months pregnant, it varies from 10 to 18 hours. In infants and young children, the half-life may be longer than in adults. With common coffee and a very rare half-life of 100 hours, it would require 3 cups of coffee every hour for 100 hours just to reach LD₅₀. Though achieving lethal dose with coffee would be exceptionally difficult, there have been many reported deaths from intentional overdosing on caffeine pills. Studies in humans have shown that caffeine may cause miscarriage or may slow the growth of a developing fetus when given in doses greater than 300 mg (an amount equal to three cups of coffee) a day. In addition, use of large amounts of caffeine by the mother during pregnancy may cause problems with the heart rhythm of the fetus. Excessive ingestion of caffeine can result in increased blood pressure and pulse, increased urine production, vasoconstriction (tightening or constricting of superficial blood vessels) sometimes resulting in cold hands or fingers, increased amounts of fatty acids in the blood, and increased production of gastric acid. Those suffering from overdose should seek medical attention. If medical care is not possible, they should find a quiet place to rest. Within an hour after the effects first arise, peak influence on the body should occur, with a 15-30 minute plateau, after which the effects should abate and the sufferer can return to normal activity.

Withdrawal

Caffeine withdrawal usually manifests itself in long drawn-out headaches. A feeling of "pressure" is created and the sufferer has difficulty concentrating and maintaining a train of thought. Unless the user can identify the fact that they are going into caffeine withdrawal, usually they regard it as a common or garden headache. The feeling is sometimes described as similar to dehydration, but can be recognized by the fact that from soon after they get up (assuming morning usage) the feeling slowly comes on then stays steady. Although painkillers such as asprin can relieve symptoms, often a small dose of caffeine does the best job. A cup of white or black tea relieves the symptoms quite well and almost instantly.

Abuse

Caffeine, in its many forms, has been used for its stimulating effects. In modern times, though, the substance can be produced in much higher quantities, and has found its way into many products. Purer forms, such as those in caffeine pills, are easily available. These pills are sometimes used by college students and shift workers to last an entire night without sleep. Caffeine pills have been under media fire for recent and past deaths of students, usually take on the form of a caffeine overdose. One such example of this was the death of a North Carolina student, Jason Allen. He swallowed most of a bottle of 90 such pills [http://www.collegepublisher.com/media/paper87/DFPArchive/science/1103981.html]. This was the equivalent of about 250 cups of coffee (or, alternatively, a gallon and a half (5 liters) of espresso, or 22 gallons (~85 liters) of caffeinated Mountain Dew (this soft drink is not available in caffeinated form in all areas). Allen probably ingested about 18 grams of caffeine, since caffeine pills are restricted to 200 milligrams or less in the U.S., and most manufacturers make them in that size. A few other deaths by caffeine overdose have been known, almost always in the case of massive pill consumption. Long periods of abuse can lead to detrimental effects on the esophagus; persons who consume high amounts of caffeine may have a risk for higher incidents of peptic ulcers, erosive esophagitis, and gastroesophageal reflux disease. They may also have heart problems, insomnia, chronic muscle tension, and nervousness. The term caffeinism has been coined to mean addiction to (or debilitating dependence on) caffeine.

References

- Weinberg BA, Bealer BK. The world of caffeine. New York & London: Routledge, 2001. ISBN 0-415-92722-6.
- Noever, R., J. Cronise, and R. A. Relwani. 1995. Using spider-web patterns to determine toxicity. NASA Tech Briefs 19(4):82. Published in New Scientist magazine, 27 April 1995.

External links

- [http://www.nlm.nih.gov/medlineplus/druginfo/uspdi/202105.html US National Library of Medicine: MedlinePlus® Drug Information: Caffeine]
- [http://www.erowid.org/chemicals/caffeine/caffeine.shtml Erowid Caffeine Vault]
- [http://www.mrkland.com/fun/xocoatl/caffeine.htm Caffeine in chocolate?]
- [http://chemistry.about.com/od/moleculescompounds/a/caffeine.htm Caffeine Chemistry]
- [http://www.CaffeineWeb.com Site dedicated to "Caffeinism's Mimicry of Mental Illness"]
- [http://www.thenakedscientists.com/html/columnists/dalyacolumn2.htm Why do plants make caffeine?]
- [http://www.cspinet.org/new/cafchart.htm Caffeine Content of Foods]
- [http://www.benbest.com/health/caffeine.html Is Caffeine a Health Hazard?]
- [http://www.coffeefaq.com/caffaq.html The Caffeine FAQ]
- [http://www.compchemwiki.org/index.php?title=Caffeine Computational Chemistry Wiki]
- [http://www.energyfiend.com/death-by-caffeine/ Death by Caffeine Calculator (humor)]
- [http://www.energyfiend.com/the-caffeine-database/ Caffeine content of drinks, mints, chocolates, and pills]
- [http://www.nescafe.com/ Nescafe - Coffee company] Category:Xanthines Category:Coffee ms:Kafeina ja:カフェイン simple:Caffeine th:คาเฟอีน

Ion

: This article is about the electrically charged particle. For other uses of this word, see ion (disambiguation). An ion is an atom or group of atoms with a net electric charge. A negatively charged ion, which has more electrons in its electron shell than it has protons in its nucleus, is known as an anion, for it is attracted to anodes, and a positively charged ion, which has fewer electrons than protons, is known as a cation (pronounced cat-eye-on), for it is attracted to cathodes. The process of converting into ions and the state of being ionized is called ionization. The recombining of ions and electrons to form neutral atoms is called recombination. Polyatomic anions which contain oxygen are sometimes known as oxyanion. Atomic and polyatomic ions are denoted by a superscript with the sign of the net electric charge and the number of electrons lost or gained, if more than one. For example: H⁺, S O₃²⁻. A collection of non-aqueous ions, or even a gas containing a proportion of charged particles, is called a plasma, which is called the fourth state of matter because its properties are quite different from solids, liquids, and gases.

Ionization potential

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⁻. Francium has the lowest ionization energy of all the elements and fluorine has the greatest.

Other ions

A dianion is a species which has two negative charges on it. For example, the dianion of pentalene is aromatic. A zwitterion is an ion with a net charge of zero, but has both a positive and negative charge on it.

History

Ions were first theorized by Michael Faraday around 1830, to describe the portions of molecules that travel either to an anode or to a cathode. However, the mechanism by which this was achieved was not described until 1884 by Svante August Arrhenius in his doctoral dissertation to the University of Uppsala. His theory was initially not accepted but his dissertation won the Nobel Prize in Chemistry in 1903.

Etymology

The word ion is a name given by Michael Faraday, from Greek , neutral present participle of , "to go", thus "a goer". So, anion, , and cation, κ, mean "(a thing) going up" and "(a thing) going down", respectively, and anode, , and cathode, κ, mean "a going up" and "a going down", respectively, from , "way".

Applications

Ions are essential to life. Sodium, potassium, calcium and other ions play an important role in the cells of living organisms, particularly in cell membranes. They have many practical, everyday applications in items such as smoke detectors and are also finding use in unconventional technologies such as ion engines and ion cannons. Category:Physical chemistry ko:이온 ms:Ion ja:イオン simple:Ion th:ไอออน

Roman numerals

The system of Roman numerals is a numeral system originating in ancient Rome, and was adapted from Etruscan numerals. The system used in antiquity was slightly modified in the Middle Ages to produce the system we use today. It is based on certain letters which are given values as numerals: :I or i for one, :V or v for five, :X or x for ten, :L or l for fifty, :C or c for one hundred (centum), :D or d for five hundred, :M or m for one thousand (mille). For larger numbers (five thousand and above), a bar is placed above a base numeral to indicate multiplication by 1000. : for five thousand : for ten thousand : for fifty thousand : for one hundred thousand : for five hundred thousand : for one million Roman numerals are commonly used today in numbered lists (in outline format), clockfaces, pages preceding the main body of a book, chord triads in music analysis, the numbering of movie sequels, and the numbering of some sport events, like the Super Bowls or Olympic Games. For arithmetics involving Roman numerals, see Roman arithmetic and Roman abacus.

Origins

Although the Roman numerals are now written with letters of the Roman alphabet, they were originally separate symbols. The Etruscans, for example, used I Λ X ⋔ 8 ⊕ for I V X L C M. They appear to derive from notches on tally sticks, such as those used by Italian and Dalmatian shepherds into the 19^th century. Thus, the I descends from a notch scored across the stick. Every fifth notch was double cut (⋀, ⋁, ⋋, ⋌, etc.), and every tenth was cross cut (X), much like European tally marks today. This produced a positional system: Eight on a counting stick was eight tallies, IIIIΛIII, but this could be written ΛIII (or VIII), as the Λ implies the four prior notches. Likewise, number four on the stick was the I-notch that could be felt just before the cut of the V, so it could be written as either IIII or IV. Thus the system was neither additive nor subtractive in its conception, but ordinal. When the tallies were later transfered to writing, the marks were easily identified with the existing Roman letters I, V, X. (A folk etymology has it that the V represented a hand, and that the X was made by placing two Vs on top of each other, one inverted.) The tenth V or X along the stick received an extra stroke. Thus 50 was written variously as N, И, K, Ψ, ⋔, etc., but perhaps most often as a chicken-track shape like a superimposed V and I. This had flattened to ⊥ (an inverted T) by the time of Augustus, and soon thereafter became identified with the graphically similar letter L. Likewise, 100 was variously Ж, ⋉, ⋈, H, or as any of the symbols for 50 above plus an extra stroke. The form Ж (that is, a superimposed X and I) came to predominate, was written variously as >I< or ƆIC, was then shortened to Ɔ or C, with C finally winning out because, as a letter, it stood for centum (Latin for 'hundred'). The hundredth V or X was marked with a box or circle. Thus 500 was like a Ɔ superposed on a ⋌ or ⊢ (that is, like a Þ with a cross bar), becoming a struck-through D or a Ð by the time of Augustus, under the graphic influence of the letter D. It was later identified as the letter D. Meanwhile, 1000 was a circled X: Ⓧ, ⊗, ⊕, and by Augustinian times was partially identified with the Greek letter Φ. It then evolved along several independent routes. Some variants, such as Ψ and CD (more accurately a reversed D adjacent to a regular D), were historical dead ends (although folk etymology later identified D for 500 as half of Φ for 1000 because of the CD variant), while two variants of ↀ survive to this day. One, CIƆ, lead to the convention of using parentheses to indicate multiplication by 1000 (later extended to double parentheses as in ↁ, ↂ, etc.); in the other, ↀ became ∞ and ⋈, eventually changing to M under the influence of the word mille ('thousand').

Zero

In general, the number zero did not have its own Roman numeral, but the concept of zero as a number was well known by all medieval computists (responsible for calculating the date of Easter). They included zero (via the Latin word nulla meaning nothing) as one of nineteen epacts, or the age of the moon on March 22. The first three epacts were nullae, xi, and xxii (written in minuscule or lower case). The first known computist to use zero was Dionysius Exiguus in 525, but the concept of zero was no doubt well known earlier. Only one instance of a Roman numeral for zero is known. About 725, Bede or one of his colleagues used the letter N, the initial of nullae, in a table of epacts, all written in Roman numerals. A notation for the value zero is quite distinct from the role of the digit zero in a positional notation system. The lack of a zero digit prevented Roman numerals from developing into a positional notation, and led to their gradual replacement by Arabic numerals in the early second millennium.

IIII or IV?

The notation of Roman numerals has varied through the centuries. Originally, it was common to use IIII to represent "four", because IV represented the god Jove (and later YHWH). The subtractive notation (which uses IV instead of IIII) has become universally used only in modern times. For example, Forme of Cury, a manuscript from 1390, uses IX for "nine", but IIII for "four". Another document in the same manuscript, from 1381, uses IV and IX. A third document in the same manuscript uses both IIII and IV, and IX. Constructions such as IIX for "eight" have also been discovered. In many cases, there seems to have been a certain reluctance in the use of the less intuitive subtractive notation. Its use increased the complexity of performing Roman arithmetic, without conveying the benefits of a full positional notation system.

Calendars and clocks

Clock faces that are labelled using Roman numerals conventionally show IIII for 4 o'clock and IX for 9 o'clock, using the subtractive principle in one case and not in the other. There are several suggested explanations for this, several of which may be true:
- The four-character form IIII creates a visual symmetry with the VIII on the other side, which IV would not.
- The number of symbols on the clock totals twenty I's, four V's, and four X's, so clock makers need only a single mold with five I's, a V, and an X in order to make the correct number of numerals for the clocks, cast four times for each clock: :: V IIII IX :: VI II IIX :: VII III X :: VIII I IX :IIX and one of the IX's can be rearranged or inverted to form XI and XII. The alternative uses seventeen I's, five V's, and four X's, possibly requiring the clock maker to have several different molds.
- IIII was the preferred way for the ancient Romans to write 4, since they to a large extent avoided subtraction.
- It has been suggested that since IV is the first two letters of IVPITER, the main god of the Romans, it was not appropriate to use.
- The I symbol would be the only symbol in the first 4 hours of the clock, the V symbol would only appear in the next 4 hours, and the X symbol only in the last 4 hours. This would add to the clock's radial symmetry.
- IV is difficult to read upside down and on an angle, particularly at that location on the clock.
- Louis XIV, king of France, preferred IIII over IV, ordered his clockmakers to produce clocks with IIII and not IV, and thus it has remained.

XCIX or IC?

Rules regarding Roman numerals often state that a symbol representing 10^x may not precede any symbol larger than 10^x+1. For example, C cannot be preceded by I or V, only by X (or, of course, by a symbol representing a value larger than C). Thus, one should represent the number "ninety-nine" as XCIX, not as the "shortcut" IC. However, these rules are not universally followed. This 'problem' manifested in questions as to why 1999 was not written simply IMM or MIM.

Year in Roman numerals

In seventeenth century Europe, using Roman numerals for the year of publication for books was standard; there were many other places it was used as well. Publishers attempted to make the number easier to read by those more accustomed to Arabic positional numerals. On British title pages, there were often spaces between the groups of digits: M DCC LXI is one example. This may have come from the French, who separated the groups of digits with periods, as: M.DCC.LXI. or M. DCC. LXI. Notice the period at the end of the sequence; many foreign countries did this for Roman numerals in general, but not necessarily Britain. (Periods were also common on each side of numerals in running text, as in "commonet .iij. viros illos".) These practices faded from general use before the start of the twentieth century, though the cornerstones of major buildings still occasionally use them. Roman numerals are today still used on building faces for dates: 2005 can be represented as MMV. The film industry has used them perhaps since its inception to denote the year a film was made, so that it could be redistributed later, either locally or to a foreign country, without making it immediately clear to viewers what the actual date was. This became more useful when films were broadcast on television to partially conceal the age of films. From this came the policy of the broadcasting industry, including the BBC, to use them to denote the year in which a television program was made (the Australian Broadcasting Corporation has largely stopped this practice but still occasionally lapses).

Other modern usage by English-speaking peoples

Roman numerals remained in common use until about the 14th century, when they were replaced by Arabic numerals (thought to have been introduced to Europe from al-Andalus, by way of Arab traders and arithmetic treatises, around the 11th century). The use of Roman numerals today is mostly restricted to ordinal numbers, such as volumes or chapters in a book or the numbers identifying monarchs or popes (e.g. Elizabeth II, Benedict XVI, etc.). Sometimes the numerals are written using lower-case letters (thus: i, ii, iii, iv, etc.), particularly if numbering paragraphs or sections within chapters, or for the pagination of the front matter of a book. Undergraduate degrees at British universities are generally graded using I, IIi, IIii, III for first, upper second (often pronounced "two one"), lower second (often pronounced "two two") and third class respectively. Modern English usage also employs Roman numerals in many books (especially anthologies), movies (e.g., Star Wars), sporting events (e.g., the Super Bowl), and historic events (e.g., World War I, World War II ). The common unifying theme seems to be stories or events that are episodic or annual in nature, with the use of classical numbering suggesting importance or timelessness. In chemistry, Roman numerals were used to denote the group in the periodic table of the elements. But there was not international agreement as to whether the group of metals which dissolve in water should be called Group IA or IB, for example, so although references may use them, the international norm has recently switched to Arabic numerals. In music theory a scale degrees or diatonic functions are often identified by Roman numerals (as in chord symbols) as follows:

Modern non-English speaking usage

The above uses are customary for English-speaking countries. Although many of them are also maintained in other countries, those countries have additional uses for Roman numerals which are unknown in English-speaking regions. The French, the Portuguese, and the Spanish use capital Roman numerals to denote centuries. For example, 'XVIII' refers to the eighteenth century, so as to avoid confusion between the '18^th century' and the '1800s'. (The Italians take the opposite approach, basing names of centuries on the digits of the years; quattrocento for example is the Italian name for the fifteenth century.) Some scholars in English-speaking countries have adopted the French method, among them Lyon Sprague de Camp. In Germany, Poland, and Russia, mixed Roman numerals are used to record dates. Just as an old clock recorded the hour by Roman numerals while the minutes were measured in Arabic numerals, the month is written in Roman numerals while the day is in Arabic numerals: 14-VI-1789 is June the fourteenth, 1789. This is how dates are inscribed on the walls of the Kremlin, for example. This method has the advantage that days and months are not confused in rapid note-taking, and that any range of days or months can be expressed without confusion. For instance, V-VIII is May to August, while 1-V-31-VIII is May first to August thirty-first. In Eastern Europe, especially the Baltic nations, Roman numerals are used to represent the days of the week in hours-of-operation signs displayed in windows or on doors of businesses. Monday is represented by I, which is the initial day of the week. Sunday is represented by VII, which is the final day of the week. The hours of operation signs are tables composed of two columns where the left column is the day of the week in Roman numerals and the right column is a range of hours of operation from starting time to closing time. The following example hours-of-operation table would be for a business whose hours of operation are 9:30AM to 5:30PM on Mondays, Wednesdays, and Thursdays; 9:30AM to 7:00PM on Tuesdays and Fridays; and 9:30AM to 1:00PM on Saturdays; and which is closed on Sundays. Since the French use capital Roman numerals to refer to the quarters of the year ('III' is the third quarter), and this has become the norm in some European standards organisation, the mixed Roman-Arabic method of recording the date has switched to lowercase Roman numerals in many circles, as '4-viii-1961'. (ISO has since specified that dates should be given in all Arabic numerals, in ISO 8601 formats.) In Romania, Roman numerals are used for floor numbering.

Alternate forms

In the Middle Ages, Latin writers used a horizontal line above a particular numeral to represent one thousand times that numeral, and additional vertical lines on both sides of the numeral to denote one hundred times the number, as in these examples: : for one thousand : for five thousand : || for one hundred thousand : || for five hundred thousand The same overline was also used with a different meaning, to clarify that the characters were numerals. Sometimes both underline and overline were used, e. g. , and in certain font-faces, particularly Times New Roman, the capital letters when used without spaces simulates the appearance of the under/over bar, e.g. MCMLXVII, which is often exagerated when written by hand. Sometimes 500, usually D, was written as I followed by an apostrophus, resembling a backwards C (Ɔ), while 1,000, usually M, was written as CIƆ. This is believed to be a system of encasing numbers to denote thousands (imagine the Cs as parentheses). This system has its origins from Etruscan numeral usage. The D and M symbols to represent 500 and 1,000 were most likely derived from IƆ and CIƆ, respectively. An extra Ɔ denoted 500, and multiple extra Ɔs are used to denote 5,000, 50,000, etc. For example: Sometimes CIƆ was reduced to an lemniscate symbol (

\infty

) for denoting 1,000. John Wallis is often credited for introducing this symbol to represent infinity, and one conjecture is that he based it off of this usage, since 1,000 was hyperbolically used to represent very large numbers. In medieval times, before the letter j emerged as a distinct letter, a series of letters i in Roman numerals was commonly ended with a flourish; hence they actually looked like ij, iij, iiij, etc. This proved useful in preventing fraud, as it was impossible, for example, to add another i to vij to get viij. This practice is now merely an antiquarian's note; it is never used. (It did, however, lead to the Dutch diphthong IJ.)

Table of Roman numerals

The "modern" Roman numerals, post-Victorian era, are shown below: An accurate way to write large numbers in Roman numerals is to handle first the thousands, then hundreds, then tens, then units.
Example: the number 1988.
One thousand is M, nine hundred is CM, eighty is LXXX, eight is VIII.
Put it together: MCMLXXXVIII (ⅯⅭⅯⅬⅩⅩⅩⅤⅠⅠⅠ). Unicode has a number of characters specifically designated as Roman numerals, as part of the Number Forms range from U+2160 to U+2183. For example, MCMLXXXVIII could alternatively be written as ⅯⅭⅯⅬⅩⅩⅩⅧ. This range includes both upper- and lowercase numerals, as well as pre-combined glyphs for numbers up to 12 (Ⅻ or XII), mainly intended for the clock faces for compatibility with non–West-European encodings. The pre-combined glyphs should only be used to represent the individual numbers where the use of individual glyphs is not wanted, and not to replace compounded numbers. Similarly precombined glyphs for 5000 and 10000 exist. The Unicode characters are present only for compatibility with other character standards which provide these characters; for ordinary uses, the regular Latin letters are preferred. Displaying these characters requires a user agent that can handle Unicode and a font that contains appropriate glyphs for them.

Games

After the Renaissance, the Roman system could also be used to write chronograms. It was common to put in the first page of a book some phrase, so that when adding the I, V, X, L, C, D, M present in the phrase, the reader would obtain a number, usually the year of publication. The phrase was often (but not always) in Latin, as chronograms can be rendered in any language that utilises the Roman alphabet.

References

External links

- [http://ostermiller.org/calc/roman.html Roman Numeral Conversion Calculator and Self Test]
- [http://www.ubr.com/clocks/faq/iiii.html FAQ: Roman IIII vs. IV on Clock Dials]
- [http://www.straightdope.com/classics/a2_153 Why do clocks with Roman numerals use "IIII" instead of "IV"?] (from The Straight Dope)
- [http://web.archive.org/web/20041119032330/http://www.wilkiecollins.demon.co.uk/roman/front.htm Roman Numerals listing from Archive.org]
- [http://alanwood.net/unicode/number_forms.html Roman numbers in Unicode] Category:Ancient Rome ko:로마 숫자 ja:ローマ数字 th:เลขโรมัน

Oxyanion

Definition

An oxyanion is a polyatomic ion with a negative charge that contains oxygen.

Examples

- nitrate ion, NO₃^-
- sulfate ion, SO₄^2-
- perchlorate ion, ClO₄^-
- aluminate ion, Al₂O₄^2-
- iodate ion, IO₃^- See category for a bigger list. Category:Anions

Inorganic nomenclature

Naming simple ionic compounds

List of common ion names

Naming hydrates

Naming molecular compounds

Naming acids

Compositional nomenclature

Substitutive nomenclature

See also

References

External links

Systematic name

See also

External links

Chemical compound

Types of compounds

See also

International Union of Pure and Applied Chemistry

See also

External link

Inorganic compound

Organic and inorganic

Inorganic compounds and living organisms

Inorganic Carbon compounds

Types of inorganic compounds

Inorganic Chemistry

See also

Chemical formula

Elements

Molecular and structural formulas

Polymers

Ions

Isotopes

Empirical formula

See also

IUPAC nomenclature of organic chemistry

Alkanes

Alkenes and Alkynes

Alcohols

Halogenated compounds

Ketones

Aldehydes

Carboxylic acids

Ethers

Esters

Amines and Amides

Cyclic compounds

Order of precedence of groups

Common nomenclature

Ketones

Aldehydes

Ions

Hydron

Parent hydride cations

Cations and substitution

See also

References

External links

Caffeine

Chemical properties

Physical properties

Caffeine extraction

Sources

Coffee

Teas and other infusions

Chocolate

Other sources

Equivalents to 200 mg of caffeine

History

Mechanism of Action

Metabolism and toxicology

Toxicity

Withdrawal

Abuse

References

External links

Ion

Ionization potential

Other ions

History