Editing Mendelevium (section)

==Production and isolation==
The lightest isotopes (<sup>244</sup>Md to <sup>247</sup>Md) are mostly produced through bombardment of [[bismuth]] targets with [[argon]] ions, while slightly heavier ones (<sup>248</sup>Md to <sup>253</sup>Md) are produced by bombarding [[plutonium]] and [[americium]] targets with ions of [[carbon]] and [[nitrogen]]. The most important and most stable isotopes are in the range from <sup>254</sup>Md to <sup>258</sup>Md and are produced through bombardment of [[einsteinium]] with alpha particles: einsteinium-253, −254, and −255 can all be used. <sup>259</sup>Md is produced as a [[decay product|daughter]] of <sup>259</sup>[[nobelium|No]], and <sup>260</sup>Md can be produced in a [[Nuclear reaction#Transfer reactions|transfer reaction]] between einsteinium-254 and [[oxygen-18]].<ref name="Silva16301" /> Typically, the most commonly used isotope <sup>256</sup>Md is produced by bombarding either einsteinium-253 or −254 with alpha particles: einsteinium-254 is preferred when available because it has a longer half-life and therefore can be used as a target for longer.<ref name="Silva16301" /> Using available microgram quantities of einsteinium, [[femtogram]] quantities of mendelevium-256 may be produced.<ref name="Silva16301" />

The recoil [[momentum]] of the produced mendelevium-256 atoms is used to bring them physically far away from the einsteinium target from which they are produced, bringing them onto a thin foil of metal (usually [[beryllium]], [[aluminium]], [[platinum]], or [[gold]]) just behind the target in a vacuum.<ref name="Silva16313">Silva, pp. 1631–3</ref> This eliminates the need for immediate chemical separation, which is both costly and prevents reusing of the expensive einsteinium target.<ref name="Silva16313" /> The mendelevium atoms are then trapped in a gas atmosphere (frequently [[helium]]), and a gas jet from a small opening in the reaction chamber carries the mendelevium along.<ref name="Silva16313" /> Using a long [[capillary tube]], and including [[potassium chloride]] aerosols in the helium gas, the mendelevium atoms can be transported over tens of [[meter]]s to be chemically analyzed and have their quantity determined.<ref name="book2" /><ref name="Silva16313" /> The mendelevium can then be separated from the foil material and other [[fission product]]s by applying acid to the foil and then [[coprecipitation|coprecipitating]] the mendelevium with [[lanthanum fluoride]], then using a [[cation-exchange]] resin column with a 10% [[ethanol]] solution saturated with [[hydrochloric acid]], acting as an [[eluant]]. However, if the foil is made of gold and thin enough, it is enough to simply dissolve the gold in [[aqua regia]] before separating the trivalent actinides from the gold using [[anion-exchange]] [[chromatography]], the eluant being 6&nbsp;M&nbsp;hydrochloric acid.<ref name="Silva16313" />

Mendelevium can finally be separated from the other trivalent actinides using selective elution from a cation-exchange resin column, the eluant being ammonia α-HIB.<ref name="Silva16313" /> Using the gas-jet method often renders the first two steps unnecessary.<ref name="Silva16313" /> The above procedure is the most commonly used one for the separation of transeinsteinium elements.<ref name="Silva16313" />

Another possible way to separate the trivalent actinides is via solvent extraction chromatography using bis-(2-ethylhexyl) phosphoric acid (abbreviated as HDEHP) as the stationary organic phase and [[nitric acid]] as the mobile aqueous phase. The actinide elution sequence is reversed from that of the cation-exchange resin column, so that the heavier actinides elute later. The mendelevium separated by this method has the advantage of being free of organic complexing agent compared to the resin column; the disadvantage is that mendelevium then elutes very late in the elution sequence, after fermium.<ref name="book2" /><ref name="Silva16313" />

Another method to isolate mendelevium exploits the distinct elution properties of Md<sup>2+</sup> from those of Es<sup>3+</sup> and Fm<sup>3+</sup>. The initial steps are the same as above, and employs HDEHP for extraction chromatography, but coprecipitates the mendelevium with terbium fluoride instead of lanthanum fluoride. Then, 50&nbsp;mg of [[chromium]] is added to the mendelevium to reduce it to the +2 state in 0.1&nbsp;M&nbsp;hydrochloric acid with [[zinc]] or [[mercury (element)|mercury]].<ref name="Silva16313" /> The solvent extraction then proceeds, and while the trivalent and tetravalent lanthanides and actinides remain on the column, mendelevium(II) does not and stays in the hydrochloric acid. It is then reoxidized to the +3 state using [[hydrogen peroxide]] and then isolated by selective elution with 2&nbsp;M&nbsp;hydrochloric acid (to remove impurities, including chromium) and finally 6&nbsp;M&nbsp;hydrochloric acid (to remove the mendelevium).<ref name="Silva16313" /> It is also possible to use a column of cationite and zinc amalgam, using 1&nbsp;M&nbsp;hydrochloric acid as an eluant, reducing Md(III) to Md(II) where it behaves like the [[alkaline earth metals]].<ref name="Silva16313" /> Thermochromatographic chemical isolation could be achieved using the volatile mendelevium [[hexafluoroacetylacetonate]]: the analogous fermium compound is also known and is also volatile.<ref name="Silva16313" />