|Name in Saurian|| Xunbadaim (Xb)|
|Systematic name|| Unpenthexium (Uph)|
|Location on the periodic table|
|Above element||Rutherfordium (104Rf)|
|Previous element||Vanthoffium (155Vh)|
|Next element||Kelvinium (157Ke)|
|Atomic mass||444.6902 u, 738.4254 yg|
|Atomic radius||134 pm, 1.34 Å|
|Van der Waals radius||200 pm, 2.00 Å|
|Nucleons||441 (156 p+, 285 n0)|
|Nuclear radius||9.10 fm|
|Electron configuration|| [Mc] 5g18 6f14 7d2 8s2 8p2|
2, 8, 18, 32, 50, 32, 10, 4
|Oxidation states|| −2, 0, +2, +3, +4, +6|
(mildly acidic oxide)
|First ionization energy||396.9 kJ/mol, 4.113 eV|
|Electron affinity||21.6 kJ/mol, 0.224 eV|
|Covalent radius||142 pm, 1.42 Å|
|Molar mass||444.690 g/mol|
|Molar volume||17.438 cm3/mol|
|Atomic number density|| 1.35 × 1021 g−1|
3.45 × 1022 cm−3
|Average atomic separation||307 pm, 3.07 Å|
|Speed of sound||3561 m/s|
|Crystal structure||Face centered cubic|
|Melting point|| 1040.32 K, 1872.57°R|
|Boiling point|| 3155.53 K, 5679.95°R|
|Liquid range||2115.21 K, 3807.37°R|
|Triple point|| 1040.28 K, 1872.50°R|
@ 21.345 μPa, 1.6010 × 10−5 torr
|Critical point|| 9344.57 K, 16820.23°R|
@ 399.1525 MPa, 3939.341 atm
|Heat of fusion||9.548 kJ/mol|
|Heat of vaporization||306.519 kJ/mol|
|Heat capacity|| 0.05180 J/(g•K), 0.09324 J/(g•°R)|
23.035 J/(mol•K), 41.464 J/(mol•°R)
|Universe (by mass)|| Relative: 5.86 × 10−37|
Absolute: 1.96 × 1016 kg
Hawkinium is the fabricated name of a hypothetical element with the symbol Hk and atomic number 156. Hawkinium was named in honor of Stephen Hawking (1942–), who made famous contributions to the understanding about black holes, including that black holes emit radiation called Hawking radiation, theoretical cosmology, and quantum gravity. This element is known in the scientific literature as unpenthexium (Uph), dvi-hafnium, or simply element 156. Hawkinium is the heaviest member of the titanium family (below titanium, zirconium, hafnium, and rutherfordium) and is the second member of the vanthoffide series; this element is located in the periodic table coordinate 7d2.
Hawkinium is a ductile, malleable, dense, silvery metal. It is slightly denser than rutherfordium (25.5 g/cm3 vs. 23.4 g/cm3) and the densest known naturally-occurring element (osmium). The atoms form face centered cubic crystal structure and is paramagnetic. The sound travels through the metal at 3561 m/s.
Thermal properties of hawkinium is not similar to lighter homologues hafnium and rutherfordium that its melting point and boiling point are much lower due to closed electron shells. Its melting point is 1040 K, which is a big drop off from 2409 K for rutherfordium and 2506 K for hafnium; its boiling point of 3156 K is also a big drop-off from 5768 K for rutherfordium and 4876 K for hafnium. However, hawkinium has higher liquid ratio (3.03) than rutherfordium (2.39) and hafnium (1.95).
Hawkinium atom masses 444.69 daltons, four times that of tin atom and twice that of radon atom. Almost all of atom's mass is in the tiny center where it contains about three quarters of all component particles. The remaining quarter are electrons orbiting the nucleus, there are 156 total, hence its atomic number. Even though f-block ended two elements ago, this element added the last electron to the f-orbital to complete that orbital, due to spin-orbit coupling. The electron configuration is what the periodic table expects, except for two electrons in the 8p1/2 orbital that extended the g-block series. The atom sizes at 134 pm in radius, similar to zinc. However if atom is a hard sphere, its real size would be 149 pm.
Like every other element heavier than lead, hawkinium has no stable isotopes. The most stable isotope is 441Hk with a half-life of 98⅔ seconds. It undergoes spontaneous fission, splitting into two or three lighter nuclei plus neutrons like the examples.
Like other elements, hawkinium contains several metastable isomers with the longest being 442mHk, whose half-life is 3.31 hours, over 120 times longer than the most stable ordinary isotope.
Due to its completed f-orbital and number of electrons in the d-orbital consistent with what the periodic table expects, hawkinium would have similar chemical properties to lighter cogeners. However during chemical reactions, hawkinium gives up two electrons in the d-orbital instead of two in the s-orbital due to d-orbital having lower partial ionization energy than s-orbital due to relativistic effects. As a result, +2 is the most stable oxidation state, such as in binary chalcides.
Hawkinium chalcides are HkO (sky blue ionic crystals), HkS (peach crystals), HkSe (brown amorphous solid), HkTe (gray amorphous solid), and HkPo (reddish brown amorphous solid). In addition to chalcides, there are halides and pnictides, such as HkF2, HkCl2, HkBr2, HkI2, HkAt2, Hk3N2, Hk3P2, Hk3As2, Hk3Sb2, and Hk3Bi2.
Hawkinium salts include HkSO4, HkCO3, and Hk(NO3)2. Organic compounds of hawkinium (organohawkinium) include hawkinocene ((C5H5)2Hk), which is a blue crystalline solid, which chloridizes to hawkinocene dichloride ((C5H5)2HkCl2, which is a yellow crystalline solid.
Occurrence and synthesis Edit
It is almost certain that hawkinium 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 hawkinium 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 hawkinium in the universe by mass is 5.86 × 10−37, which amounts to 1.96 × 1016 kilograms.
To go along with other such civilizations, humans on Earth may eventually have the capability to synthesize hawkinium. To synthesize most stable isotopes of hawkinium, 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, 441Hk.