Editing Mendelevium (section)

===Chemical===
The chemistry of mendelevium is mostly known only in solution, in which it can take on the +3 or +2 [[oxidation state]]s. The +1 state has also been reported, but has not yet been confirmed.<ref name="Silva16356">Silva, pp. 1635–6</ref>

Before mendelevium's discovery, [[Glenn T. Seaborg|Seaborg]] and Katz predicted that it should be predominantly trivalent in aqueous solution and hence should behave similarly to other tripositive lanthanides and actinides. After the synthesis of mendelevium in 1955, these predictions were confirmed, first in the observation at its discovery that it [[elution|eluted]] just after fermium in the trivalent actinide elution sequence from a cation-exchange column of resin, and later the 1967 observation that mendelevium could form insoluble [[hydroxide]]s and [[fluoride]]s that coprecipitated with trivalent lanthanide salts.<ref name="Silva16356" /> Cation-exchange and solvent extraction studies led to the conclusion that mendelevium was a trivalent actinide with an ionic radius somewhat smaller than that of the previous actinide, fermium.<ref name="Silva16356" /> Mendelevium can form [[coordination complex]]es with 1,2-cyclohexanedinitrilotetraacetic acid (DCTA).<ref name="Silva16356" />

In [[redox|reducing]] conditions, mendelevium(III) can be easily reduced to mendelevium(II), which is stable in aqueous solution.<ref name="Silva16356" /> The [[standard reduction potential]] of the ''E''°(Md<sup>3+</sup>→Md<sup>2+</sup>) couple was variously estimated in 1967 as −0.10&nbsp;V or −0.20&nbsp;V:<ref name="Silva16356" /> later 2013 experiments established the value as {{val|−0.16|0.05|u=V}}.<ref>
{{cite journal |last1=Toyoshima |first1=Atsushi |last2=Li |first2=Zijie |first3=Masato |last3=Asai |first4=Nozomi |last4=Sato |first5=Tetsuya K. |last5=Sato |first6=Takahiro |last6=Kikuchi |first7=Yusuke |last7=Kaneya |first8=Yoshihiro |last8=Kitatsuji |first9=Kazuaki |last9=Tsukada |first10=Yuichiro |last10=Nagame |first11=Matthias |last11=Schädel |first12=Kazuhiro |last12=Ooe |first13=Yoshitaka |last13=Kasamatsu |first14=Atsushi |last14=Shinohara |first15=Hiromitsu |last15=Haba |first16=Julia |last16=Even |date=11 October 2013 |title=Measurement of the Md<sup>3+</sup>/Md<sup>2+</sup> Reduction Potential Studied with Flow Electrolytic Chromatography |journal=Inorganic Chemistry |volume=52 |issue=21 |pages=12311–3 |doi=10.1021/ic401571h|pmid=24116851 }}</ref> In comparison, ''E''°(Md<sup>3+</sup>→Md<sup>0</sup>) should be around −1.74&nbsp;V, and ''E''°(Md<sup>2+</sup>→Md<sup>0</sup>) should be around −2.5&nbsp;V.<ref name="Silva16356" /> Mendelevium(II)'s elution behavior has been compared with that of [[strontium]](II) and [[europium]](II).<ref name="Silva16356" />

In 1973, mendelevium(I) was reported to have been produced by Russian scientists, who obtained it by reducing higher oxidation states of mendelevium with [[samarium]](II). It was found to be stable in neutral water–[[ethanol]] solution and be [[Homologous series|homologous]] to [[caesium]](I). However, later experiments found no evidence for mendelevium(I) and found that mendelevium behaved like divalent elements when reduced, not like the monovalent [[alkali metal]]s.<ref name="Silva16356" /> Nevertheless, the Russian team conducted further studies on the [[thermodynamics]] of cocrystallizing mendelevium with alkali metal [[chloride]]s, and concluded that mendelevium(I) had formed and could form mixed crystals with divalent elements, thus cocrystallizing with them. The status of the +1 oxidation state is still tentative.<ref name="Silva16356" />

The electrode potential ''E''°(Md<sup>4+</sup>→Md<sup>3+</sup>) was predicted in 1975 to be +5.4&nbsp;V; 1967 experiments with the strong oxidizing agent [[sodium bismuthate]] were unable to oxidize mendelevium(III) to mendelevium(IV).<ref name="Silva16356" />