Editing Nobelium (section)

===Atomic===
A nobelium atom has 102 electrons. They are expected to be arranged in the configuration [Rn]5f<sup>14</sup>7s<sup>2</sup> (ground state [[term symbol]] <sup>1</sup>S<sub>0</sub>), although experimental verification of this electron configuration had not yet been made as of 2006. The sixteen electrons in the 5f and 7s subshells are [[valence electron]]s.<ref name="Silva1639" /> In forming compounds, three valence electrons may be lost, leaving behind a [Rn]5f<sup>13</sup> core: this conforms to the trend set by the other actinides with their [Rn]5f<sup>''n''</sup> electron configurations in the tripositive state. Nevertheless, it is more likely that only two valence electrons are lost, leaving behind a stable [Rn]5f<sup>14</sup> core with a filled 5f<sup>14</sup> shell. The first [[ionization potential]] of nobelium was measured to be at most (6.65&nbsp;±&nbsp;0.07)&nbsp;[[electronvolt|eV]] in 1974, based on the assumption that the 7s electrons would ionize before the 5f ones;<ref name="NIST">{{cite journal |first1=William C. |last1=Martin |first2=Lucy |last2=Hagan |first3=Joseph |last3=Reader |first4=Jack |last4=Sugar |s2cid=97945150 |date=1974 |title=Ground Levels and Ionization Potentials for Lanthanide and Actinide Atoms and Ions |journal=[[Journal of Physical and Chemical Reference Data]] |volume=3 |issue=3 |pages=771–9 |doi=10.1063/1.3253147 |bibcode=1974JPCRD...3..771M |url=https://pdfs.semanticscholar.org/9618/febdd51cee0e84ff7af88767be47cfcd4818.pdf |archive-url=https://web.archive.org/web/20200215124722/https://pdfs.semanticscholar.org/9618/febdd51cee0e84ff7af88767be47cfcd4818.pdf |url-status=dead |archive-date=2020-02-15 }}</ref> this value has not yet been refined further due to nobelium's scarcity and high radioactivity.<ref>Lide, David R. (editor), ''CRC Handbook of Chemistry and Physics, 84th Edition'', CRC Press, Boca Raton (FL), 2003, section 10, ''Atomic, Molecular, and Optical Physics; Ionization Potentials of Atoms and Atomic Ions''</ref> The ionic radius of [[coordination number|hexacoordinate]] and octacoordinate No<sup>3+</sup> had been preliminarily estimated in 1978 to be around 90 and 102&nbsp;pm respectively;<ref name="Silva163941" /> the ionic radius of No<sup>2+</sup> has been experimentally found to be 100&nbsp;pm to two [[significant figure]]s.<ref name="Silva1639" /> The [[enthalpy of hydration]] of No<sup>2+</sup> has been calculated as 1486&nbsp;kJ/mol.<ref name="Silva163941" />