Editing Einsteinium (section)

===Physical===
[[File:EinsteiniumGlow.JPG|thumb|left|upright|Glow due to the intense radiation from ~300 μg of {{sup|253}}Es<ref>[[#Haire|Haire]], p. 1580</ref>]]
Einsteinium is a synthetic, silvery, radioactive metal. In the [[periodic table]], it is located to the right of the actinide [[californium]], to the left of the actinide [[fermium]] and below the lanthanide [[holmium]] with which it shares many similarities in physical and chemical properties. Its density of 8.84&nbsp;g/cm{{sup|3}} is lower than that of californium (15.1&nbsp;g/cm{{sup|3}}) and is nearly the same as that of holmium (8.79&nbsp;g/cm{{sup|3}}), despite einsteinium being much heavier per atom than holmium. Einsteinium's melting point (860&nbsp;°C) is also relatively low – below californium (900&nbsp;°C), fermium (1527&nbsp;°C) and holmium (1461&nbsp;°C).<ref name="CRC">Hammond C. R. "The elements" in {{RubberBible86th}}</ref><ref name="HAIRE_1990">Haire, R. G. (1990) "Properties of the Transplutonium Metals (Am-Fm)", in: Metals Handbook, Vol.&nbsp;2, 10th edition, (ASM International, Materials Park, Ohio), pp. 1198–1201.</ref> Einsteinium is a soft metal, with a [[bulk modulus]] of only 15&nbsp;GPa, one of the lowest among non-[[alkali metal]]s.<ref name="h1591">[[#Haire|Haire]], p. 1591</ref>

Unlike the lighter actinides [[californium]], [[berkelium]], [[curium]] and [[americium]], which crystallize in a double [[hexagonal crystal family|hexagonal]] structure at ambient conditions; einsteinium is believed to have a [[Cubic crystal system|face-centered cubic]] (''fcc'') symmetry with the space group ''Fm''{{overline|3}}''m'' and the lattice constant {{nowrap|''a'' {{=}} 575&nbsp;pm}}. However, there is a report of room-temperature hexagonal einsteinium metal with {{nowrap|''a'' {{=}} 398 pm}} and {{nowrap|''c'' {{=}} 650 pm}}, which converted to the ''fcc'' phase upon heating to 300&nbsp;°C.<ref name="ev" />

The self-damage induced by the radioactivity of einsteinium is so strong that it rapidly destroys the crystal lattice,<ref name="g1268" /> and the energy release during this process, 1000 watts per gram of <sup>253</sup>Es, induces a visible glow.<ref name="h1579">[[#Haire|Haire]], p. 1579</ref> These processes may contribute to the relatively low density and melting point of einsteinium.<ref name="ES_METALL">{{cite journal|last1=Haire|first1=R. G.|last2=Baybarz|first2=R. D.|doi=10.1051/jphyscol:1979431|title=Studies of einsteinium metal|date=1979|pages=C4–101|volume=40|journal=Le Journal de Physique|s2cid=98493620 |url=http://hal.archives-ouvertes.fr/docs/00/21/88/27/PDF/ajp-jphyscol197940C431.pdf|access-date=2010-11-24|archive-date=2012-03-07|archive-url=https://web.archive.org/web/20120307233020/http://hal.archives-ouvertes.fr/docs/00/21/88/27/PDF/ajp-jphyscol197940C431.pdf|url-status=live}} [http://www.osti.gov/bridge/servlets/purl/6582609-SrTVod/6582609.pdf draft manuscript] {{Webarchive|url=https://web.archive.org/web/20190710170812/http://www.osti.gov/bridge/servlets/purl/6582609-SrTVod/6582609.pdf |date=2019-07-10 }}</ref> Further, due to the small size of available samples, the melting point of einsteinium was often deduced by observing the sample being heated inside an electron microscope.<ref name="s61">[[#Seaborg|Seaborg]], p. 61</ref> Thus, surface effects in small samples could reduce the melting point.

The metal is trivalent and has a noticeably high volatility.<ref>{{cite journal|last1=Kleinschmidt|first1=Phillip D.|last2=Ward|first2=John W.|last3=Matlack|first3=George M.|last4=Haire|first4=Richard G.|title=Henry's Law vaporization studies and thermodynamics of einsteinium-253 metal dissolved in ytterbium|journal=The Journal of Chemical Physics|volume=81|issue=1|pages=473–477|date=1984|doi=10.1063/1.447328|bibcode = 1984JChPh..81..473K }}</ref> In order to reduce the self-radiation damage, most measurements of solid einsteinium and its compounds are performed right after thermal annealing.<ref name="s52">[[#Seaborg|Seaborg]], p. 52</ref> Also, some compounds are studied under the atmosphere of the reductant gas, for example H{{sub|2}}O+[[hydrogen chloride|HCl]] for EsOCl so that the sample is partly regrown during its decomposition.<ref name="s60" />

Apart from the self-destruction of solid einsteinium and its compounds, other intrinsic difficulties in studying this element include scarcity – the most common {{sup|253}}Es isotope is available only once or twice a year in sub-milligram amounts – and self-contamination due to rapid conversion of einsteinium to berkelium and then to californium at a rate of about 3.3% per day:<ref name="ES_F3" /><ref name="ES2O3" /><ref name="s55">[[#Seaborg|Seaborg]], p. 55</ref>
:<chem>
^{253}_{99}Es ->[\alpha][20 \ce{d}] ^{249}_{97}Bk ->[\beta^-][314 \ce{d}] ^{249}_{98}Cf
</chem>

Thus, most einsteinium samples are contaminated, and their intrinsic properties are often deduced by extrapolating back experimental data accumulated over time. Other experimental techniques to circumvent the contamination problem include selective optical excitation of einsteinium ions by a tunable laser, such as in studying its luminescence properties.<ref name="s76">[[#Seaborg|Seaborg]], p. 76</ref>

Magnetic properties have been studied for einsteinium metal, its oxide and fluoride. All three materials showed [[Curie–Weiss law|Curie–Weiss]] [[paramagnetic]] behavior from [[liquid helium]] to room temperature. The effective magnetic moments were deduced as {{val|10.4|0.3|u=[[Bohr magneton|''μ''{{sub|B}}]]}} for Es{{sub|2}}O{{sub|3}} and {{val|11.4|0.3|u=''μ''{{sub|B}}}} for the EsF{{sub|3}}, which are the highest values among actinides, and the corresponding [[Curie temperature]]s are 53 and 37 K.<ref>{{cite journal|last1=Huray|first1=P.|last2=Nave|first2=S.|last3=Haire|first3=R.|title=Magnetism of the heavy 5f elements|journal=Journal of the Less Common Metals|volume=93|pages=293–300|date=1983|doi=10.1016/0022-5088(83)90175-3|issue=2}}</ref><ref>{{cite journal|last1=Huray|first1=Paul G.|last2=Nave|first2=S. E.|last3=Haire|first3=R. G.|last4=Moore|first4=J. R.|title=Magnetic Properties of Es{{sub|2}}O{{sub|3}} and EsF{{sub|3}}|journal=Inorganica Chimica Acta|volume=94|issue=1–3|pages=120–122|date=1984|doi=10.1016/S0020-1693(00)94587-0}}</ref>