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Symbol Kf
Atomic number 167
Pronunciation /'kərsh•uf•ē•(y)üm/
Named after Gustav Kirchhoff
Name in Saurian Bahsxevvaim (Bv)
Systematic name Unhexseptium (Uhs)
Location on the periodic table
Group 13
Period 8
Family Boron family (Icosagens)
Series Kirchoffide series
Coordinate 8p1
Element above Kirchoffium Nihonium
Element left of Kirchoffium Higgsium
Element right of Kirchoffium Bornium
Atomic properties
Subatomic particles 646
Atomic mass 483.0102 u, 802.0573 yg
Atomic radius 158 pm, 1.58 Å
Covalent radius 163 pm, 1.63 Å
van der Waals radius 208 pm, 2.08 Å
Nuclear properties
Nucleons 479 (167 p+, 312 no)
Nuclear ratio 1.87
Nuclear radius 9.35 fm
Half-life 880.38 μs
Decay mode Spontaneous fission
Decay product Various
Electronic properties
Electron notation 167-9-26
Electron configuration [Og] 5g18 6f14 7d10 8s2 8p2 9s2 9p1
Electrons per shell 2, 8, 18, 32, 50, 32, 18, 4, 3
Oxidation states +1, +3, +5
(a mildly basic oxide)
Electronegativity 1.31
First ionization energy 621.7 kJ/mol, 6.443 eV
Electron affinity 65.9 kJ/mol, 0.683 eV
Physical properties
Bulk properties
Molar mass 483.010 g/mol
Molar volume 28.6458 cm3/mol
Density 16.862 g/cm3
Atomic number density 1.25 × 1021 g−1
2.10 × 1022 cm−3
Average atomic separation 362 pm, 3.62 Å
Speed of sound 3577 m/s
Magnetic ordering Diamagnetic
Crystal structure Face-centered cubic
Color Indigo
Phase Solid
Thermal properties
Melting point 1403.63 K, 2526.53°R
1130.48°C, 2066.86°F
Boiling point 1345.14 K, 2421.25°R
1071.99°C, 1961.58°F
Liquid range −58.49 K, −105.28°R
Liquid ratio 0.96
Triple point 1403.62 K, 2526.52°R
1130.47°C, 2066.85°F
@ 750.31 kPa, 5627.8 torr
Critical point 3175.30 K, 5715.53°R
2902.15°C, 5255.86°F
@ 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•K), 0.08532 J/(g•°R)
22.896 J/(mol•K), 41.212 J/(mol•°R)
Abundance in the universe
By mass Relative: 2.89 × 10−35
Absolute: 9.68 × 1017 kg
By atom 1.57 × 10−36

Kirchoffium is the provisional non-systematic name of a theoretical element with the symbol Kf and atomic number 167. Kirchoffium was named in honor of Gustav Kirchhoff (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 8p1 coordinate on the periodic table.

Atomic properties Edit

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.

Isotopes Edit

Like every other element heavier than lead, kirchoffium has no stable isotopes. The longest-lived isotope is 479Kf with a brief half-life of about 880.4 microseconds. It undergoes spontaneous fission, splitting into three lighter nuclei plus neutrons like the example.

Kf → 205
Tl + 133
Cs + 69
Ga + 72 1

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, a little less than 250,000 times longer than the most stable ground state isotope 479Kf.

Chemical properties and compounds Edit

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 gibbsium while Kf+ has an electron configuration of higgsium. 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 KfNhTlN.

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.

Physical properties Edit

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).

Kirchoffium has a face-centered cubic crystal lattice.

Occurrence Edit

It is almost certain that kirchoffium doesn't exist on Earth at all, but it is believe to barely exist somewhere in the universe due to its brief lifetime. Every element heavier than iron can only naturally be produced by exploding stars. But it is likely 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 can only be produced by advanced technological civilizations, virtually accounting for all of its abundance in the universe. An estimated abundance of Kirchoffium in the universe by mass is 2.89 × 10−35, which amounts to 9.68 × 1017 kilograms or about six times the mass of Saturn's moon Prometheus available in the universe.

Synthesis Edit

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 impossible using current technology since it requires a tremendous amount of energy, thus its cross section would be so low that it is beyond the technological limit. Even if synthesis succeeds, this resulting element would immediately undergo fission. Here's couple of example equations in the synthesis of the most stable isotope, 479Kf.

Bk + 174
Yb + 58 1
n → 479
Db + 152
Sm + 55 1
n → 479
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
1 H He
2 Li Be B C N O F Ne
3 Na Mg Al Si P S Cl Ar
4 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
5 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
6 Cs Ba La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
7 Fr Ra Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Tn Og
8 Nw G * Du Sh Hb Da Bo Fa Av So Hr Wt Dr Le Vh Hk Ke Ap Vw Hu Fh Ma Kp Gb Bc Hi Kf Bn J Hm Bs Rs
* Ls Dm Ms Ts Dt Mw Pk By Bz Fn Dw To Pl Ah My Cv Fy Ch A Ed Ab Bu

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