Editing Group 5 element (section)

=== Dubnium ===

[[File:7s electrons dubnium relativistic vs nonrelativistic.svg|thumb|Relativistic (solid line) and nonrelativistic (dashed line) radial distribution of the 7s valence electrons in dubnium.]]
A direct relativistic effect is that as the atomic numbers of elements increase, the innermost electrons begin to revolve faster around the nucleus as a result of an increase of [[electromagnetic attraction]] between an electron and a nucleus. Similar effects have been found for the outermost s [[Atomic orbital|orbitals]] (and p<sub>1/2</sub> ones, though in dubnium they are not occupied): for example, the 7s orbital contracts by 25% in size and is stabilized by 2.6&nbsp;[[electronvolt|eV]].<ref name="Haire" />

A more indirect effect is that the contracted s and p<sub>1/2</sub> orbitals [[shielding effect|shield]] the charge of the nucleus more effectively, leaving less for the outer d and f electrons, which therefore move in larger orbitals. Dubnium is greatly affected by this: unlike the previous group 5 members, its 7s electrons are slightly more difficult to extract than its 6d electrons.<ref name="Haire" />

[[File:Atomic orbitals dubnium.svg|thumb|Relativistic stabilization of the ''n''s orbitals, the destabilization of the {{nobreak|(''n''-1)d}} orbitals and their spin–orbit splitting for the group 5 elements.]]
Another effect is the [[spin–orbit interaction]], particularly spin–orbit splitting, which splits the 6d subshell—the [[azimuthal quantum number]] ℓ of a d&nbsp;shell is 2—into two subshells, with four of the ten orbitals having their ℓ lowered to 3/2 and six raised to 5/2. All ten energy levels are raised; four of them are lower than the other six. (The three 6d electrons normally occupy the lowest energy levels, 6d<sub>3/2</sub>.)<ref name="Haire" />

A single ionized atom of dubnium (Db<sup>+</sup>) should lose a 6d electron compared to a neutral atom; the doubly (Db<sup>2+</sup>) or triply (Db<sup>3+</sup>) ionized atoms of dubnium should eliminate 7s electrons, unlike its lighter homologs. Despite the changes, dubnium is still expected to have five valence electrons; 7p energy levels have not been shown to influence dubnium and its properties. As the 6d orbitals of dubnium are more destabilized than the 5d ones of tantalum, and Db<sup>3+</sup> is expected to have two 6d, rather than 7s, electrons remaining, the resulting +3 oxidation state is expected to be unstable and even rarer than that of tantalum. The ionization potential of dubnium in its maximum +5 oxidation state should be slightly lower than that of tantalum and the ionic radius of dubnium should increase compared to tantalum; this has a significant effect on dubnium's chemistry.<ref name=Haire>{{cite book| title=The Chemistry of the Actinide and Transactinide Elements| editor1-last=Morss|editor1-first=L.R.|editor2-first=N. M.| editor2-last=Edelstein| editor3-last=Fuger|editor3-first=Jean| last1=Hoffman|first1=D. C. |last2=Lee |first2=D. M. |last3=Pershina |first3=V.|chapter=Transactinides and the future elements| publisher= [[Springer Science+Business Media]]| year=2006| isbn=978-1-4020-3555-5| edition=3rd|pages=1652–1752| ref=CITEREFHaire2006}}</ref>

Atoms of dubnium in the solid state should arrange themselves in a [[body-centered cubic]] configuration, like the previous group 5 elements.<ref name="bcc" /> The predicted density of dubnium is 21.6&nbsp;g/cm<sup>3</sup>.<ref name="density" />