| Chemical Properties | Back Directory | [Definition]
Nonmetallic halogen element of atomic number 53;
group VIIA of the periodic table; the least reactive
of the halogens, aw 126.9045; valences = 1,3,5,7;
no stable isotopes but many artificial radioactive
isotopes. | [Appearance]
Heavy, grayish-black plates or granules having a metallic luster; characteristic odor.
Readily sublimed having a violet vapor.Soluble in alcohol, carbon
disulfide, chloroform, ether, carbon tetrachloride,
glycerol, and alkaline iodide solutions; insoluble | [Dielectric constant]
11.0（Ambient） | [InChI]
InChI=1S/I2/c1-2 | [InChIKey]
PNDPGZBMCMUPRI-UHFFFAOYSA-N | [History]
Discovered by Courtois in 1811. Iodine, a halogen, occurs sparingly in the form of iodides in sea water from which it is assimilated by seaweeds, in Chilean saltpeter and nitrate-bearing earth, known as caliche in brines from old sea deposits, and in brackish waters from oil and salt wells. Ultrapure iodine can be obtained from the reaction of potassium iodide with copper sulfate. Several other methods of isolating the element are known. Iodine is a bluish-black, lustrous solid, volatilizing at ordinary temperatures into a blue-violet gas with an irritating odor; it forms compounds with many elements, but is less active than the other halogens, which displace it from iodides. Iodine exhibits some metallic-like properties. It dissolves readily in chloroform, carbon tetrachloride, or carbon disulfide to form beautiful purple solutions. It is only slightly soluble in water. Iodine compounds are important in organic chemistry and very useful in medicine. Forty-two isotopes and isomers are recognized. Only one stable isotope, 127I, is found in nature. The artificial radioisotope 131I, with a half-life of 8 days, has been used in treating the thyroid gland. The most common compounds are the iodides of sodium and potassium (KI) and the iodates (KIO3). Lack of iodine is the cause of goiter. Iodides and thyroxin, which contains iodine, are used internally in medicine, and a solution of KI and iodine in alcohol is used for external wounds. Potassium iodide finds use in photography. The deep blue color with starch solution is characteristic of the free element. Care should be taken in handling and using iodine, as contact with the skin can cause lesions; iodine vapor is intensely irritating to the eyes and mucous membranes. Elemental iodine costs about 25 to 75￠/g depending on purity and quantity. | [SMILES]
II | [Uses]
Iodine is a halogen element extracted from chilean nitrate-bearing
earth or from seaweed. it functions by its presence in the thyroid
hormones. iodine deficiency is associated with goiter. sources are
potassium and cuprous iodide and potassium and calcium iodate, of
which the iodate form is preferred because of better stability. it is
used as a food supplement. | [CAS DataBase Reference]
12190-71-5 |
| Hazard Information | Back Directory | [Chemical Properties]
Heavy, grayish-black plates or granules having a metallic luster; characteristic odor.
Readily sublimed having a violet vapor.Soluble in alcohol, carbon
disulfide, chloroform, ether, carbon tetrachloride,
glycerol, and alkaline iodide solutions; insoluble | [Hazard]
Toxic by ingestion and inhalation, strong
irritant to eyes and skin. Questionable carcinogen. | [Physical properties]
Iodine in its pure state is a black solid that sublimates (changes from a solid to a gas withoutgoing through a liquid state) at room temperature. It produces a deep purple vapor that is irritatingto the eyes, nose, and throat. Iodine tends to form nonmetallic diatomic molecules (I2).It is the heaviest of the naturally occurring halogens. (Although astatine, the fifth element ingroup 17, is heavier than iodine, it is a synthetic element and does not occur in nature exceptas a very small trace.) Iodine is the least reactive of the five halogens.
Iodine’s melting point is 113.7°C, its boiling point is 184.4°C, and its density is 4.93g/cm3. | [Isotopes]
There are a total of 145 isotopes of iodine. Only one (I-127) is stable andaccounts for 100% of iodine’s natural abundance on Earth. All the other 146 isotopesare radioactive with half-lives ranging from a 150 nanoseconds to 1.57×10+7 | [Origin of Name]
The name originates from the Greek word iodes, meaning “violet-colored,”
which is the color of iodine’s vapor. | [Occurrence]
Iodine is the 64th most abundant element on Earth. It occurs widely over the Earth, butnever in the elemental form and never in high concentrations.
It occurs in seawater where some species of seaweed and kelp accumulate the elementin their cells. It is also recovered from deep brine wells found in Chile, Indonesia, Japan,and Michigan, Arkansas, and Oklahoma in the United States. The iodine is recovered fromcremated ashes of seaweed. The ashes are leached with water to remove the unwanted salts.Finally, manganese dioxide (MnO2) is added to oxidize the iodine ions (I1-) to produceelemental diatomic iodine (I2). The following reaction takes place: 4I1- + MnO2 → MnI2 +I2 + 2O2-.
Chilean saltpeter [potassium nitrate (KNO3)] has a number of impurities, includingsodium and calcium iodate. Iodine is separated from the impurities and, after being treatedchemically, finally produces diatomic iodine. Today, iodine is mostly recovered from sodiumiodate (NaIO3) and sodium periodate (NaIO4) obtained from Chile and Bolivia. | [Characteristics]
Iodine is the least reactive of the elements in the halogen group 17. Most people associateiodine with the dark-brown color of the tincture of iodine used as an antiseptic for minor skinabrasions and cuts. A tincture is a 50% solution of iodine in alcohol. Although it is still used,iodine is no longer the antibiotic of choice for small skin wounds. Since iodine is a poisonthat kills bacteria, iodine tablets are often used by campers and others to purify water that istaken from outdoor streams. | [Industrial uses]
Iodine is a purplish-black, crystalline, poisonouselementary solid, chemical symbol I, bestknown for its use as a strong antiseptic in medicine,but also used in many chemical compoundsand war gases. In tablet form it is usedfor sterilizing drinking water, and has less odorand taste than chlorine for this purpose. It isalso used in cattle feeds. Although poisonousin quantity, iodine is essential to proper cellgrowth in the human body, and is found in everycell in a normal body, with larger concentrationin the thyroid gland.
A wide range of compounds are made forelectronic and chemical uses. Iodine is also achemical reagent, used for reducing vanadiumpentoxide and zirconium oxide into highpuritymetals. |
| Questions And Answer | Back Directory | [Description]
Iodine,I, is a nonmetallic element with an orthorhombic crystal structure, a violet to black color. This poisonous element sublimes readily and is easily purified in this manner. It is insoluble in water,but is soluble in common solvents such as alcohol, ether,and carbon tetrachloride. Iodine is used as a germicide, an antiseptic, in dyes,tinctures, and pharmaceuticals. It is also used in the production of vanadium metal in the McKechnie-Seybolt process, which is the reduction of vanadium pentoxide in the presence of iodine. Iodine is used in a similar manner in the production of high-purity zirconium.
For many years, iodine tincture(3% to 7% dissolved in ethyl alcohol) has been an important antiseptic. The commercial tinctures also usually contain 5% potassium iodide to provide stability. This form produces a mild burning of the skin and stains both skin and fabrics. A milder preparation is available in which about 2% iodine is contained in an oil-water emulsion which also contains lecithin.
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