|Name in Saurian|| Bahsxevvaim (Bv)|
|Systematic name|| Unhexseptium (Uhs)|
|Location on the periodic table|
|Above element||Nihonium (113Nh)|
|Previous element||Hubbium (166Hb)|
|Next element||Bornium (168Bn)|
|Family||Boron family (Icosagens)|
|483.0102 u, 802.0573 yg|
|Atomic radius||158 pm, 1.58 Å|
|Van der Waals radius||208 pm, 2.08 Å|
|s||479 (167 p+, 312 n0)|
|Electron configuration|| [Gb] 9s2 9p1|
2, 8, 18, 32, 50, 32, 18, 4, 3
|Oxidation states|| +1, +3, +5|
(mildly basic oxide)
|First ionization energy||621.7 kJ/mol, 6.443 eV|
|Electron affinity||65.9 kJ/mol, 0.683 eV|
|Covalent radius||163 pm, 1.63 Å|
|Molar mass||483.010 g/mol|
|Molar volume||28.6458 cm3/mol|
|Atomic number density|| 1.25 × 1021 g−1|
2.10 × 1022 cm−3
|Average atomic separation||362 pm, 3.62 Å|
|Crystal structure||Face centered cubic|
|Melting point|| 1403.63 K, 2526.53°R|
|Boiling point|| 1345.14 K, 2421.25°R|
|Liquid range||−58.49 , −105.28|
|Triple point|| 1403.62 K, 2526.52°R|
@ 750.31 kPa, 5627.8 torr
|Critical point|| 3175.30 K, 5715.53°R|
@ 177.2426 MPa, 1749.254 atm
|Heat of fusion||15.270 kJ/mol|
|Heat of vaporization||143.388 kJ/mol|
|Heat capacity|| 0.04740 J/(g• ), 0.08532 J/(g• )|
22.896 J/(mol• ), 41.212 J/(mol• )
|Universe (by mass)|| Relative: 2.89 × 10−45|
Absolute: 9.68 × 107 kg
Kirchoffium is the fabricated name of a hypothetical element with the symbol Kf and atomic number 167. Kirchoffium was named in honor of Gustav Kirchoff (1824–1887), who contributed to the fundamental understanding of electrical circuits, spectroscopy, and the emission of black-body radiation by heated objects. This element is known in the scientific literature as unhexseptium (Uhs), dvi-thallium, or simply element 167. Kirchoffium is the heaviest icosagen and is the first member of the namesake kirchoffide series, placing this element at 9p1 coordinate on the periodic table.
Kirchoffium is diamagnetic, meaning that its magnetic field is activated when externally applied. It is an indigo metal with density approaching 20 g/cm3. The reason why this metal is indigo instead of gray-white typical of most metals is because the energy gap between ground states and lowest excited states is very narrow due to relativistic effects. It is so narrow that electrons oscillate in the indigo region of the visible spectrum.
The element sublimates at 1072°C (2421°R), which means at that temperature kirchoffium goes directly from solid to gas or back without becoming a liquid first. Liquid kirchoffium is nonexistent because our atmospheric pressure is not enough. Its liquid state exists at pressure at least 750 kPa, and our atmospheric pressure is just 101 kPa. At 750 kPa, its boiling point would be identical to its melting point at 1130°C (2527°R).
Its electronegativity is 1.71 and has five valence electrons. After completing the 9s orbital, the electrons are filling the 9p orbital as if skipping all the blocks between s and p. In the nucleus, there are 479 particles (167 protons, 312 neutrons), corresponding to its mass number.
Like every other element heavier than lead, kirchoffium has no stable isotopes. The most stable isotope is 479Kf with a brief half-life of about 16¾ microseconds. It undergoes spontaneous fission, splitting into three lighter nuclei plus neutrons like the example.
Kirchoffium has meta states, several are much longer lived than the most stable ground state isotope. The longest lived meta state is 474mKf with a half-life of 21 seconds, more than a million times longer than the most stable ground state isotope.
Kirchoffium should have chemical properties similar to thallium and nihonium according to the periodic trend. However, due to the outermost valence not similar to other boron family members, then its chemical properties can deviate from other members. Still, oxidation states of kirchoffium is not much different from other members. Like all other members except for the lighter cogener becquerelium, +3 is the most stable oxistate with +1 and +5 being less common. Kf3+ has a electron configuration of gibbium while Kf+ has an electron configuration of hubbium. Kirchoffium has similar first ionization energy to thallium (6.44 eV vs. 6.11 eV), but it is the most electropositive boron member. As a result, kirchoffium would behave chemically like a boron group. Like all other lighter cogeners, Kf can easily form binary pnictides, such as KfN, as well as polyicosagen pnictides like KfTlAs and KfBcTlN.
Kirchoffium(III) nitride (KfN) is a white crystalline solid which melts at 1170°C (2598°R), kirchoffium(III) phosphide (KfP) is a yellow crystalline solid, and kirchoffium(III) arsenide is an aqua green solid. It can form intericosagen compounds with kirchoffium, such as KfB, KfAl, and KfGa.
Kirchoffium don't just form pnictides and icosides, but also chalcides and halides, such as Kf2O3, Kf2Se, KfF5, KfCl3, and KfI.
Occurrence and synthesis Edit
It is almost certain that kirchoffium doesn't exist on Earth at all, but it is believe to exist somewhere in the universe, at least barely. Since every element heavier than lithium were produced by stars, then kirchoffium must be produced in stars, and then thrown out into space by exploding stars. But it is theoretically impossible for even the most powerful supernovae or most violent neutron star collisions to produce this element through r-process because there's not enough energy available or not enough neutrons, respectively, to produce this hyperheavy element. Instead, this element virtually can only be made by advanced technological civilizations. An estimated abundance of Kirchoffium in the universe by mass is 2.89 × 10−45, which amounts to 9.68 × 107 kilograms or about the mass of the world's heaviest train.
To go along with other such civilizations, humans on Earth may eventually have the capability to synthesize kirchoffium. To synthesize most stable isotopes of kirchoffium, nuclei of a couple lighter elements must be fused together, and right amount of neutrons must be seeded. This operation would be extremely difficult since it requires a vast amount of energy and even if nuclei of this element were produced would immediately decay due to its brief half-life. Here's couple of example equations in the production of the most stable isotope, 479Kf.