Wikipedia:WikiProject Chemicals/Chembox validation/VerifiedDataSandbox and Calcium fluoride: Difference between pages

{{Chembox

| verifiedrevid = 476999594

| ImageSize2 =

| IUPACName =

| OtherNames =

|Section1={{Chembox Identifiers

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| SMILES1 = F[Ca]F

| CASNo_Ref = {{cascite|correct|CAS}}

| EINECS = 232-188-7

| PubChem = 24617

| RTECS = EW1760000

|Section2={{Chembox Properties

| Formula = | Ca=1 | F=2

| Appearance = White crystalline solid (single crystals are transparent)

| Density = 3.18 g/cm³

| MeltingPtC = 1418

| BoilingPtC = 2533

| Solubility = 0.015 g/L (18 °C)<br>0.016 g/L (20 °C)

| SolubilityProduct = 3.9 × 10⁻¹¹ <ref>Pradyot Patnaik. ''Handbook of Inorganic Chemicals''. McGraw-Hill, 2002, {{ISBN|0-07-049439-8}}</ref>

| SolubleOther = insoluble in [[acetone]]<br>slightly soluble in acid

| RefractIndex = 1.4338

| MagSus = -28.0·10⁻⁶ cm³/mol

}}

|Section3={{Chembox Structure

| CrystalStruct = [[cubic crystal system]], [[pearson symbol|''cF12'']]<ref>X-ray Diffraction Investigations of CaF₂ at High Pressure, L. Gerward, J. S. Olsen, S. Steenstrup, M. Malinowski, S. Åsbrink and A. Waskowska, Journal of Applied Crystallography (1992), 25, 578-581 {{doi|10.1107/S0021889892004096}}</ref>

| Coordination = Ca, 8, cubic<br/>F, 4, tetrahedral

| LattConst_a = 5.451 Å

| LattConst_b = 5.451 Å

| LattConst_c = 5.451 Å

| LattConst_alpha = 90

| LattConst_beta =

| LattConst_gamma =

| MolShape =

| OrbitalHybridisation =

| Dipole =

}}

|Section4={{Chembox Hazards

| MainHazards = Reacts with concentrated [[sulfuric acid]] to produce [[hydrofluoric acid]]

| ExternalSDS = [http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc13/icsc1323.htm ICSC 1323]

| NFPA-H = 0

| NFPA-F = 0

| NFPA-R = 0

| NFPA-S =

| FlashPt = Non-flammable

| LDLo = >5000 mg/kg (oral, guinea pig)<br/>4250 mg/kg (oral, rat)<ref>{{IDLH|fluoride|Fluorides (as F)}}</ref>

}}

|Section8={{Chembox Related

| OtherAnions = [[Calcium chloride]]<br/>[[Calcium bromide]]<br/>[[Calcium iodide]]

| OtherCations = [[Beryllium fluoride]]<br/>[[Magnesium fluoride]]<br/>[[Strontium fluoride]]<br/>[[Barium fluoride]]

'''Calcium fluoride''' is the [[inorganic compound]] of the elements [[calcium]] and [[fluorine]] with the [[chemical formula|formula]] CaF₂. It is a white solid that is practically insoluble in water. It occurs as the mineral [[fluorite]] (also called fluorspar), which is often deeply coloured owing to impurities.

==Chemical structure==

{{main|Fluorite structure}}

The compound crystallizes in a cubic motif called the [[fluorite structure]].

[[File:Xtals combined 2 300ppi.png|thumb|left|upright=1.5|Unit cell of CaF₂, known as fluorite structure, from two equivalent perspectives. The second origin is often used when visualising point defects entered on the cation.<ref>{{Cite journal|last1=Burr|first1=P. A.|last2=Cooper|first2=M. W. D.|date=2017-09-15|title=Importance of elastic finite-size effects: Neutral defects in ionic compounds|journal=Physical Review B|volume=96|issue=9|pages=094107|doi=10.1103/PhysRevB.96.094107|arxiv=1709.02037|bibcode=2017PhRvB..96i4107B|s2cid=119056949}}</ref>]]

Ca²⁺ centres are eight-coordinate, being centered in a cube of eight F⁻ centres. Each F⁻ centre is coordinated to four Ca²⁺ centres in the shape of a tetrahedron.<ref>G. L. Miessler and D. A. Tarr "Inorganic Chemistry" 3rd Ed, Pearson/Prentice Hall publisher, {{ISBN|0-13-035471-6}}.</ref> Although perfectly packed crystalline samples are colorless, the mineral is often deeply colored due to the presence of [[F-center]]s.

The same crystal structure is found in numerous ionic compounds with formula AB₂, such as [[ceria|CeO₂]], [[zirconia|cubic ZrO₂]], [[uranium dioxide|UO₂]], [[thorium dioxide|ThO₂]], and [[plutonium dioxide|PuO₂]]. In the corresponding [[anti-structure]], called the antifluorite structure, anions and cations are swapped, such as [[beryllium carbide|Be₂C]].

===Gas phase===

The gas phase is noteworthy for failing the predictions of [[VSEPR theory]]; the {{chem2|CaF2}} molecule is not linear like {{chem2|MgF2}}, but bent with a [[bond angle]] of approximately 145°; the strontium and barium dihalides also have a bent geometry.<ref>{{Greenwood&Earnshaw}}</ref> It has been proposed that this is due to the fluoride [[ligand]]s interacting with the electron core<ref name = "Gillespie&Robinson">{{cite journal | last1 = Gillespie | first1 = R. J. | last2 = Robinson | first2 = E. A. | year = 2005 | title = Models of molecular geometry | journal = [[Chem. Soc. Rev.]] | volume = 34 | issue = 5| pages = 396–407 | doi = 10.1039/b405359c | pmid = 15852152 }}</ref><ref name = "Bytheway&Gillespie">{{cite journal | last1 = Bytheway | first1 = I. | last2 = Gillespie | first2 = R. J. | last3 = Tang | first3 = T. H. | last4 = Bader | first4 = R.F | year = 1995 | title = Core Distortions and Geometries of the Difluorides and Dihydrides of Ca, Sr, and Ba | journal = [[Inorganic Chemistry (journal)|Inorg. Chem.]] | volume = 34 | issue = 9| pages = 2407–2414 | doi = 10.1021/ic00113a023 }}</ref> or the d-subshell<ref>{{cite journal | doi = 10.1063/1.459748 | title = Ab initio model potential study of the equilibrium geometry of alkaline earth dihalides: MX₂ (M=Mg, Ca, Sr, Ba; X=F, Cl, Br, I) | year = 1991 | author = Seijo, Luis | journal = [[J. Chem. Phys.]] | volume = 94 | pages = 3762 | last2 = Barandiarán | first2 = Zoila | last3 = Huzinaga | first3 = Sigeru | issue = 5| bibcode = 1991JChPh..94.3762S | url = https://repositorio.uam.es/bitstream/10486/7315/1/41581_jchemphysseijo_91_jcp_94_3762.pdf | hdl = 10486/7315 | hdl-access = free }}</ref> of the calcium atom.

==Preparation==

The mineral [[fluorite]] is abundant, widespread, and mainly of interest as a precursor to [[hydrofluoric acid|HF]]. Thus, little motivation exists for the industrial production of CaF₂. High purity CaF₂ is produced by treating [[calcium carbonate]] with [[hydrofluoric acid]]:<ref name=Aigueperse>{{Ullmann|doi=10.1002/14356007.a11_307|title=Fluorine Compounds, Inorganic|year=2000|last1=Aigueperse|first1=Jean|last2=Mollard|first2=Paul|last3=Devilliers|first3=Didier|last4=Chemla|first4=Marius|last5=Faron|first5=Robert|last6=Romano|first6=René|last7=Cuer|first7=Jean Pierre|isbn=3527306730}}</ref>

:CaCO₃ + 2 HF → CaF₂ + CO₂ + H₂O

==Applications==

{{Main|Fluorite}}

Naturally occurring CaF₂ is the principal source of [[hydrogen fluoride]], a commodity chemical used to produce a wide range of materials.

Calcium fluoride in the [[fluorite]] state is of significant commercial importance as a fluoride source.<ref>Aigueperse, Jean; Mollard, Paul; Devilliers, Didier; Chemla, Marius; Faron, Robert; Romano, Renée; Cuer, Jean Pierre (2005), "Fluorine Compounds, Inorganic", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, p. 307, doi:10.1002/14356007.a11_307.</ref> Hydrogen fluoride is liberated from the mineral by the action of concentrated [[sulfuric acid]]:<ref>Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. {{ISBN|0-12-352651-5}}.</ref>

:CaF₂ + H₂SO₄ → [[calcium sulfate|CaSO₄]](solid) + 2 HF

===Others===

Calcium fluoride is used to manufacture optical components such as windows and lenses, used in thermal imaging systems, spectroscopy, [[telescope]]s, and [[excimer laser]]s (used for [[photolithography]] in the form of a fused lens). It is transparent over a broad range from ultraviolet (UV) to infrared (IR) frequencies. Its low refractive index reduces the need for [[anti-reflection coating]]s. Its insolubility in water is convenient as well.{{Cn|date=June 2022}} It also allows much smaller wavelengths to pass through.{{Cn|date=June 2022}}

Doped calcium fluoride, like natural fluorite, exhibits [[thermoluminescence]] and is used in [[thermoluminescent dosimeter]]s. It forms when fluorine combines with calcium.{{Cn|date=June 2022}}

==Safety==

CaF₂ is classified as "not dangerous", although reacting it with [[sulfuric acid]] produces [[hydrofluoric acid]], which is highly corrosive and toxic. With regards to inhalation, the [[National Institute for Occupational Safety and Health|NIOSH]]-recommended concentration of fluorine-containing dusts is 2.5&nbsp;mg/m³ in air.<ref name=Aigueperse/>

==See also==

*[[List of laser types]]

*[[Photolithography]]

*[[Skeletal fluorosis]]

==References==

{{Reflist}}

==External links==

*[http://webbook.nist.gov/cgi/cbook.cgi?ID=7789-75-5&Units=SI NIST webbook] thermochemistry data

*[http://www.press.uchicago.edu/Misc/Chicago/284158_townes.html Charles Townes on the history of lasers]

*[https://web.archive.org/web/20060116134617/http://www.npi.gov.au/database/substance-info/profiles/44.html National Pollutant Inventory - Fluoride and compounds fact sheet]

*[http://www.crystran.co.uk/calcium-fluoride-caf2.htm Crystran Material Data] {{Webarchive|url=https://web.archive.org/web/20121110090919/http://www.crystran.co.uk/calcium-fluoride-caf2.htm |date=2012-11-10 }}

*[http://msds.chem.ox.ac.uk/CA/calcium_fluoride.html MSDS] {{Webarchive|url=https://web.archive.org/web/20111121195835/http://msds.chem.ox.ac.uk/CA/calcium_fluoride.html |date=2011-11-21 }} (University of Oxford)

{{Calcium compounds}}

{{Fluorides}}

[[Category:Calcium compounds]]

[[Category:Crystals]]

[[Category:Fluorides]]

[[Category:Fluorite]]

[[Category:Alkaline earth metal halides]]

[[Category:Optical materials]]

[[Category:Fluorite crystal structure]]