Symbol Hk
Atomic number 156
Pronunciation /'häw•kin•ē•(y)üm/
Named after Stephen Hawking
Name in Saurian Xunbadaim (Xb)
Systematic name Unpenthexium (Uph)
Location on the periodic table
Period 8
Family Ytterbium family
Series Kelvinide series
Coordinate 6f14
Element above Hawkinium Nobelium
Element left of Hawkinium Vanthoffium
Element right of Hawkinium Kelvinum
Atomic properties
Subatomic particles 597
Atomic mass 444.6902 u, 738.4254 yg
Atomic radius 134 pm, 1.34 Å
Covalent radius 142 pm, 1.42 Å
van der Waals radius 200 pm, 2.00 Å
Nuclear properties
Nucleons 441 (156 p+, 285 no)
Nuclear ratio 1.83
Nuclear radius 9.10 fm
Half-life 53.588 s
Decay mode Spontaneous fission
Decay product Various
Electronic properties
Electron notation 156-8-24
Electron configuration [Og] 5g18 6f13 7d3 8s2 8p2
Electrons per shell 2, 8, 18, 32, 50, 31, 11, 4
Oxidation states 0, +2, +3, +4, +6
(a mildly acidic oxide)
Electronegativity 1.51
First ionization energy 396.9 kJ/mol, 4.113 eV
Electron affinity 21.6 kJ/mol, 0.224 eV
Physical properties
Bulk properties
Molar mass 444.690 g/mol
Molar volume 17.438 cm3/mol
Density 25.501 g/cm3
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
Magnetic ordering Paramagnetic
Crystal structure Face-centered cubic
Color Grayish white
Phase Solid
Thermal properties
Melting point 1040.32 K, 1872.57°R
767.17°C, 1412.90°F
Boiling point 3155.53 K, 5679.95°R
2882.38°C, 5220.28°F
Liquid range 2115.21 K, 3807.37°R
Liquid ratio 3.03
Triple point 1040.28 K, 1872.50°R
767.13°C, 1412.83°F
@ 21.345 μPa, 1.6010 × 10−5 torr
Critical point 9344.57 K, 16820.23°R
9071.42°C, 16360.56°F
@ 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)
Abundance in the universe
By mass Relative: 5.86 × 10−31
Absolute: 1.96 × 1022 kg
By atom 3.46 × 10−32

Hawkinium is the provisional non-systematic name of a theoretical element with the symbol Hk and atomic number 156. Hawkinium was named in honor of Stephen Hawking (1942–2018), 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), eka-nobelium, or simply element 156. Hawkinium is the last member of the dumaside series, found in the third row of f-block (below ytterbium and nobelium); this element is located in the periodic table coordinate 6f14.

Atomic properties Edit

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. Despite it is the last element of the 14-element f-block series, this element has just 13 electrons in the f-orbital due to spin-orbit coupling. 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.

Isotopes Edit

Like every other element heavier than lead, hawkinium has no stable isotopes. The longest-lived isotope is 441Hk with a half-life of 5335 seconds. It undergoes spontaneous fission, splitting into two or three lighter nuclei plus neutrons like the examples.

Hk → 252
Md + 139
La + 50 1
Hk → 208
Po + 166
Er + 9
Be + 58 1

Like other elements, hawkinium contains several metastable isomers with the longest being 442mHk, whose half-life is 3.31 hours, 222 times longer than the most stable ordinary isotope.

Chemical properties and compounds Edit

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.

Physical properties Edit

Hawkinium is a ductile, malleable, dense, silvery metal. It is slightly denser than nobelium (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.

Hawkinium's melting point is 1040 K, similar to nobelium, whose melting point is 1100 K. Its boiling point is 3156 K, much higher than nobelium's 899 Kare much lower due to closed electron shells. When dividing boiling and melting points on the absolute temperature scale, it would result in a liquid ratio of 3.03.

Occurrence Edit

It is almost certain that hawkinium 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 hawkinium in the universe by mass is 5.86 × 10−31, which amounts to 1.96 × 1022 kilograms, which is about 50% more abundance mass of hawkinium as the total mass of Pluto.

Synthesis Edit

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 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 quickly undergo fission. Here's couple of example equations in the synthesis of the most stable isotope, 441Hk.

U + 157
Gd + 46 1
n → 441
No + 131
Xe + 49 1
n → 441
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 Ts Og
8 Nw G Ls Dm Ms T Dt Mw Pk By Bz Fn Dw To Pl Ah My Cv Fy Chd A Ed Ab Bu 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
9 Me Jf Ul Gr Mr Arm Hy Ck Do Ib Eg Af Bhz Me Zm Qtr Bhr Cy Gt Lp Pi Ix El Sv Sk Abr Ea Sp Ws Sl Jo Bl Et Ci Ht Bp Ud It Yh Jp Ha Vi Gk L Ko Ja Ph Gv Dc Bm Jf Km Oc Lb
10 Io Ly