View source for Sodium iodide

{{Redirect|NaI|other uses|Nai (disambiguation){{!}}Nai}}
{{chembox
| Verifiedfields = changed
| verifiedrevid = 464402019
| ImageFileL1 = Sodium iodide.jpg
| ImageSizeL1 = 150px
| ImageNameL1 = Sodium iodide
| ImageFileR1 = Sodium-iodide-3D-ionic.png
| ImageSizeR1 = 120px
| ImageNameR1 = Sodium iodide
|  ImageFile2 =NaI-Tl-crystals.jpg
| ImageSize2= 270px
|  ImageCaption2 =NaI(Tl) scintillators
|Section1={{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 5048
| ChEMBL_Ref = {{ebicite|changed|EBI}}
| ChEMBL = 1644695
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = F5WR8N145C
| InChI = 1/HI.Na/h1H;/q;+1/p-1
| InChIKey = FVAUCKIRQBBSSJ-REWHXWOFAL
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 33167
| SMILES = [Na+].[I-]
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/HI.Na/h1H;/q;+1/p-1
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = FVAUCKIRQBBSSJ-UHFFFAOYSA-M
| CASNo = 7681-82-5
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo1 = 13517-06-1
| CASNo1_Comment = (dihydrate)
| CASNo1_Ref = {{cascite|changed|CAS}}
| PubChem = 5238
| RTECS = WB6475000
  }}
|Section2={{Chembox Properties
| Formula = NaI
| MolarMass = 149.894<ref name=crc>Haynes, p. 4.86</ref>
| Appearance = white solid <br> [[deliquescent]]<ref name=crc/>
| Odor = odorless
| Density = 3.67&nbsp;g&nbsp;cm<sup>−3</sup><ref name=crc/>
| Solubility = 1587&nbsp;g/L (0&nbsp;°C) <br> 1842&nbsp;g/L (25&nbsp;°C) <br> 2278&nbsp;g/L (50&nbsp;°C) <br> 2940&nbsp;g/L (70&nbsp;°C) <br> 3020&nbsp;g/L (100&nbsp;°C)<ref>{{cite book|last = Seidell|first = Atherton|title = Solubilities of inorganic and organic compounds c. 2|publisher = [[D. Van Nostrand Company]]|year = 1919|page = [https://archive.org/details/solubilitiesino01seidgoog/page/n680 655]|url = https://archive.org/details/solubilitiesino01seidgoog}}</ref><ref>Haynes, p. 5.171</ref>
| SolubleOther =ethanol, acetone<ref name=crc/>
| MeltingPtC = 661
| BoilingPtC = 1304
| MeltingPt_ref = <ref name=crc/>
| BoilingPt_ref = <ref name=crc/>
| RefractIndex = 1.93 (300 nm)<br>1.774 (589 nm)<br>1.71 (10 μm)<ref>Haynes, p. 10.250</ref>
| BandGap =  5.89 eV<ref>{{cite journal|doi=10.1143/JPSJ.27.266|title=Exciton Structure of NaI and NaBr|journal=Journal of the Physical Society of Japan|volume=27|issue=1|pages=266|year=1969|last1=Miyata|first1=Takeo|bibcode=1969JPSJ...27..266M}}</ref><ref>{{cite journal|doi=10.1103/PhysRevB.15.5921|title=Optical properties and electronic structure of alkali halides by thermoreflectivity|journal=Physical Review B|volume=15|issue=12|pages=5921–5926|year=1977|last1=Guizzetti|first1=G.|last2=Nosenzo|first2=L.|last3=Reguzzoni|first3=E.|bibcode=1977PhRvB..15.5921G}}</ref>
| MagSus = −57×10<sup>−6</sup>&nbsp;cm<sup>3</sup>&nbsp;mol<sup>−1</sup><ref>Haynes, p. 4.130</ref>
  }}
|Section3={{Chembox Structure
| Coordination = [[Octahedron|Octahedral]]
| CrystalStruct = [[Sodium chloride|Halite]], [[Pearson symbol|''cF8'']]
| SpaceGroup = Fm{{overline|3}}m, No. 225
| LattConst_a = 0.6462 nm
| UnitCellFormulas = 4
| Structure_ref=<ref>{{cite journal|doi=10.1103/PhysRev.21.143|title=Precision Measurements of Crystals of the Alkali Halides|journal=Physical Review|volume=21|issue=2|pages=143–161|year=1923|last1=Davey|first1=Wheeler P.|bibcode=1923PhRv...21..143D}}</ref>
  }}
|Section4={{Chembox Thermochemistry
| Thermochemistry_ref =<ref>Haynes, p. 5.36</ref>
| DeltaHf = −287.8&nbsp;kJ&nbsp;mol<sup>−1</sup>
| DeltaGfree =−286.1&nbsp;kJ&nbsp;mol<sup>−1</sup>
| HeatCapacity = 52.1&nbsp;J&nbsp;mol<sup>−1</sup>&nbsp;K<sup>−1</sup>
| Entropy = 98.5&nbsp;J&nbsp;mol<sup>−1</sup>&nbsp;K<sup>−1</sup>
 }}
|Section7={{Chembox Hazards
| ExternalSDS = [https://www.fishersci.com/content/dam/fishersci/en_US/documents/programs/education/regulatory-documents/sds/chemicals/chemicals-s/s25554.pdf]
| MainHazards = Irritant, can harm the unborn child
| GHSPictograms = {{GHS07}}{{GHS09}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|315|319|400}}
| PPhrases = {{P-phrases|273|305+351+338}}<ref>{{cite web|url=https://www.sigmaaldrich.com/catalog/product/sigald/383112?lang=en&region=US|title=Sodium iodide 383112|website=Sigma Aldrich}}</ref>
| NFPA-H = 1
| NFPA-F = 0
| NFPA-R = 1
| FlashPt = Non-flammable
  }}
|Section8={{Chembox Related
| OtherAnions = [[Sodium fluoride]]<br />[[Sodium chloride]]<br />[[Sodium bromide]]<br />[[Sodium astatide]]
| OtherCations = [[Lithium iodide]]<br />[[Potassium iodide]]<br />[[Rubidium iodide]]<br />[[Caesium iodide]]<br />[[Francium iodide]]
  }}
}}

'''Sodium iodide''' ([[chemical formula]] '''NaI''') is an [[ionic compound]] formed from the [[chemical reaction]] of [[sodium]] metal and [[iodine]]. Under standard conditions, it is a white, water-soluble [[solid]] comprising a 1:1 mix of sodium [[cation]]s (Na<sup>+</sup>) and [[iodide]] [[anion]]s (I<sup>−</sup>) in a [[crystal lattice]]. It is used mainly as a nutritional supplement and in [[organic chemistry]]. It is produced industrially as the [[salt (chemistry)|salt]] formed when acidic iodides react with [[sodium hydroxide]].<ref name=Ullmann/> It is a [[chaotropic agent|chaotropic salt]].

==Uses==
===Food supplement===
Sodium iodide, as well as [[potassium iodide]], is commonly used to treat and prevent [[iodine deficiency]].  Iodized table salt contains 10&nbsp;[[parts per million|ppm]] [[iodide]].<ref name=Ullmann>{{Ullmann|last = Lyday|first = Phyllis A.|year = 2005|title = Iodine and Iodine Compounds|pages = 382–390|doi = 10.1002/14356007.a14_381}}</ref>

===Organic synthesis===
[[File:NaI@DWNT.png|thumb|left|Monatomic NaI chains grown inside double-wall [[carbon nanotube]]s.<ref name=chains>{{cite journal|doi = 10.1038/ncomms8943|pmid = 26228378|pmc = 4532884|title = Single-atom electron energy loss spectroscopy of light elements|journal = [[Nature Communications]]|volume = 6|page = 7943|year = 2015|last1 = Senga|first1 = Ryosuke|last2 = Suenaga|first2 = Kazu|bibcode = 2015NatCo...6.7943S}}</ref>]]
Sodium iodide is used for conversion of [[alkyl chloride]]s into [[alkyl iodide]]s.  This method, the [[Finkelstein reaction]],<ref>{{cite journal|first = Hank|last = Finkelstein|author-link = Hans Finkelstein|journal = [[Ber. Dtsch. Chem. Ges.]]|year = 1910|volume = 43|issue = 2|pages = 1528–1532|title = Darstellung organischer Jodide aus den entsprechenden Bromiden und Chloriden|language = de|doi = 10.1002/cber.19100430257|url = https://zenodo.org/record/1426411}}</ref> relies on the insolubility of [[sodium chloride]] in [[acetone]] to drive the reaction:<ref>{{cite journal|title = Solvolytic Displacement Reactions At Saturated Carbon Atoms|first = Andrew|last = Streitwieser|author-link = Andrew Streitwieser|journal = [[Chemical Reviews]]|year = 1956|volume = 56|issue = 4|pages = 571–752|doi = 10.1021/cr50010a001}}</ref>

::R–Cl + NaI → R–I + NaCl

===Nuclear medicine===
Some radioactive iodide salts of sodium, including Na[[iodine-125|<sup>125</sup>I]] and Na[[iodine-131|<sup>131</sup>I]], have [[radiopharmaceutical]] uses for [[thyroid cancer]] and [[hyperthyroidism]] or as [[radioactive tracer]] in imaging (see [[Isotopes of iodine#Radioiodines 123I, 124I, 125I, and 131I in medicine and biology|Isotopes of iodine > Radioiodines I-123, I-124, I-125, and I-131 in medicine and biology]]).

===Thallium-doped NaI(Tl) scintillators===
Sodium iodide [[activator (phosphor)|activated]] with [[thallium]], NaI(Tl), when subjected to [[ionizing radiation]], emits [[photon]]s (i.e., [[scintillation (physics)|scintillate]]) and is used in [[scintillation detector]]s, traditionally in [[nuclear medicine]], [[geophysics]], [[nuclear physics]], and environmental measurements. NaI(Tl) is the most widely used scintillation material. The crystals are usually coupled with a [[photomultiplier tube]], in a [[hermetically sealed]] assembly, as sodium iodide is [[hygroscopic]]. Fine-tuning of some parameters (i.e., [[radiation hardness]], [[Gamma-ray burst#Afterglow|afterglow]], [[transparency and translucency|transparency]]) can be achieved by varying the conditions of the [[crystal growth]]. Crystals with a higher level of [[Dopant|doping]] are used in [[X-ray]] detectors with high spectrometric quality. Sodium iodide can be used both as [[single crystal]]s and as [[polycrystals]] for this purpose. The wavelength of maximum emission is 415&nbsp;nm.<ref>{{cite web|publisher = [[Saint-Gobain|Saint-Gobain Crystals]]|url = http://www.crystals.saint-gobain.com/sites/imdf.crystals.com/files/documents/sgc-scintillation-materials-and-assemblies.pdf|title = Scintillation Materials and Assemblies|year = 2016|access-date = June 21, 2017|archive-date = October 31, 2017|archive-url = https://web.archive.org/web/20171031153652/http://www.crystals.saint-gobain.com/sites/imdf.crystals.com/files/documents/sgc-scintillation-materials-and-assemblies.pdf|url-status = dead}}</ref>

===Radiocontrast===
[[António Egas Moniz]] searched for a [[radiocontrast]] agent for [[cerebral angiography]].<ref name="jama"/> After experiments on [[rabbit]]s and [[dog]]s he settled upon sodium iodide as the best medium.<ref name="jama">{{cite journal|issue=2|date=1968|volume=206|publisher=[[American Medical Association]] (AMA)|journal=JAMA: The Journal of the American Medical Association|issn=0098-7484|title=Antonio Egas Moniz (1874-1955) Portuguese Neurologist|pages=368–369 |doi=10.1001/jama.1968.03150020084021|pmid=4877763 }}</ref>

==Solubility data==
Sodium iodide exhibits high solubility in some organic solvents, unlike sodium chloride or even bromide:
{| class="toccolours" border="1" style="margin: 1em; border-collapse: collapse;"
!Solvent
!Solubility of NaI (g&nbsp;NaI/kg of solvent at 25&nbsp;°C)<ref>{{cite book|last = Burgess|first = John|title = Metal Ions in Solution|series = Ellis Horwood Series in Chemical Sciences|publisher = Ellis Horwood|location = New York|year = 1978|isbn = 9780470262931}}</ref>
|-
| [[Water (molecule)|H<sub>2</sub>O]] || 1842
|-
| [[Ammonia|Liquid ammonia]] || 1620
|-
| [[Sulfur dioxide|Liquid sulfur dioxide]] || 150
|-
| [[Methanol]] || 625–830
|-
| [[Formic acid]] || 618
|-
| [[Acetonitrile]] || 249
|-
| [[Acetone]] || 504<ref>{{cite journal |last1=Kowalczyk |first1=James J. |title=Sodium Iodide |journal=Encyclopedia of Reagents for Organic Synthesis |date=15 April 2001 |doi=10.1002/047084289X.rs087|isbn=0-471-93623-5 }}</ref>
|-
| [[Formamide]] || 570–850
|-
| [[Acetamide]] || 323 (41.5&nbsp;°C)
|-
| [[Dimethylformamide]] || 37–64
|-
| [[Dichloromethane]] || 0.09<ref>{{cite journal|doi = 10.1039/F19898502705|title = Transfer and partition free energies of 1:1 electrolytes in the water–dichloromethane solvent system at 298.15 K|journal = [[Journal of the Chemical Society, Faraday Transactions 1]]|volume = 85|issue = 9|pages = 2705–2712|year = 1989|last1 = De Namor|first1 = Angela F. Danil|last2 = Traboulssi|first2 = Rafic|last3 = Salazar|first3 = Franz Fernández|last4 = De Acosta|first4 = Vilma Dianderas|last5 = De Vizcardo|first5 = Yboni Fernández|last6 = Portugal|first6 = Jaime Munoz}}</ref>
|}

==Stability==
Iodides (including sodium iodide) are detectably oxidized by atmospheric [[oxygen]] (O<sub>2</sub>) to molecular [[iodine]] (I<sub>2</sub>). I<sub>2</sub> and I<sup>−</sup> complex to form the [[triiodide]] complex, which has a yellow color, unlike the white color of sodium iodide. Water accelerates the oxidation process, and iodide can also produce I<sub>2</sub> by photooxidation, therefore for maximum stability sodium iodide should be stored under dark, low temperature, low humidity  conditions.

==See also==
* [[Gamma spectroscopy]]
* [[Scintillation counter]]
* [[Teratology]]

==References==
{{reflist}}

==Cited sources==
* {{cite book | editor= Haynes, William M. | date = 2016| title = CRC Handbook of Chemistry and Physics | edition = 97th | publisher = [[CRC Press]] | isbn = 9781498754293|page=4.49| title-link = CRC Handbook of Chemistry and Physics}}

==External links==
{{Commons category|Sodium iodide}}
* {{cite web|url = http://www.inchem.org/documents/icsc/icsc/eics1009.htm|publisher = [[International Chemical Safety Card]]|title = ICSC 1009 – Sodium Iodide (Anhydrous)|date = April 20, 2005|access-date = June 21, 2017}}
* {{cite web|url = http://www.sciencelab.com/msds.php?msdsId=9927270|title = Material Safety Data Sheet (MSDS) – Safety data for sodium iodide|website = ScienceLab.com|date = May 21, 2013|access-date = June 21, 2017|archive-date = June 3, 2018|archive-url = https://web.archive.org/web/20180603000442/http://www.sciencelab.com/msds.php?msdsId=9927270|url-status = dead}}
* {{cite web|url = https://www.drugs.com/cons/sodium-iodide-oral-injection-intravenous.html|title = Sodium iodide (Oral route, Injection route, Intravenous route)|year = 2017|website = [[Drugs.com]]|access-date = June 21, 2017}}
* {{cite web|title = Safety Data Sheet – Sodium iodide |publisher = Global Safety Management|date = January 23, 2015|url = https://www.fishersci.com/content/dam/fishersci/en_US/documents/programs/education/regulatory-documents/sds/chemicals/chemicals-s/s25554.pdf|access-date = October 16, 2019}}

{{Sodium compounds}}
{{iodides}}
{{Molecules detected in outer space}}

[[Category:Alkali metal iodides]]
[[Category:Inorganic compounds]]
[[Category:Iodides]]
[[Category:Ionising radiation detectors|*]]
[[Category:Metal halides]]
[[Category:Phosphors and scintillators]]
[[Category:Sodium compounds]]
[[Category:Chaotropic agents]]
[[Category:Rock salt crystal structure]]