|Name in Saurian|| Xocmxeckjaim (Xm)|
|Systematic name|| Unseptnilium (Usn)|
|Location on the periodic table|
|Above element||Livermorium (116Lv)|
|Previous element||Joulium (169Ju)|
|Next element||Bunsenium (171Bs)|
|Family||Oxygen family (Chalcogens)|
|Atomic mass||499.1464 u, 828.8520 yg|
|Atomic radius||141 pm, 1.41 Å|
|Van der Waals radius||187 pm, 1.87 Å|
|Nucleons||495 (170 p+, 325 n0)|
|Nuclear radius||9.45 fm|
|Electron configuration|| [Gb] 8p2 9s2 9p2|
2, 8, 18, 32, 50, 32, 18, 6, 4
|Oxidation states|| +2, +4, +6, +8|
|First ionization energy||896.2 kJ/mol, 9.288 eV|
|Electron affinity||154.2 kJ/mol, 1.598 eV|
|Covalent radius||135 pm, 1.35 Å|
|Molar mass||499.146 g/mol|
|Molar volume||29.441 cm3/mol|
|Atomic number density||2.05 × 1022 cm−3|
|Average atomic separation||366 pm, 3.66 Å|
|Speed of sound||10687 m/s|
|Crystal structure||Base centered monoclinic|
|Melting point|| 672.23 K, 399.08°C|
|Boiling point|| 1331.56 K, 1058.41°C|
|Liquid range||659.33 K/°C, 1186.79°F/°R|
|Triple point|| 672.27 K, 399.12°C|
@ 66.154 Pa, 0.49619 torr
|Critical point|| 2170.90 K, 1897.75°C|
@ 9.4147 MPa, 92.917 atm
|Heat of fusion||7.270 kJ/mol|
|Heat of vaporization||124.117 kJ/mol|
|Heat capacity|| 0.05019 J/g/K, 0.09034 J/g/°R|
25.052 J/mol/K, 45.093 J/mol/°R
|Universe (by mass)|| Relative: 1.29 × 10−45|
Absolute: 4.32 × 107 kg
Helmholtzium is the fabricated name of a hypothetical element with the symbol Hm and atomic number 170. Helmholtzium was named in honor of Hermann von Helmholtz (1821–1894), who worked on the conservation of energy. This element is known in scientific literature as unseptnilium (Usn), dvi-polonium, or simply element 170. Helmholtzium is the heaviest chalcogen and is the fourth member of the kirchoffide series, placing this element at 9p4 coordinate on the periodic table.
Helmholtzium is a soft, brittle black metal that melts to a black, tar-like liquid. But first it got to be heated to 399°C and need to absorb 7.27 kJ/mol of energy in order to become a liquid. Formation of dark gray vapor would require lot more energy, at 124.12 kJ/mol and be heated even more to 1058°C in order for its vapor pressure to equal ambient pressure. If we decrease the ambient pressure, the boiling point would decrease until it reaches the melting point. This point is called triple point. For helmholtzium, it is almost identical to its melting point in temperature but at a pressure of 66.15 Pa, just 1⁄1532 the atmospheric pressure on Earth at sea level and 1⁄10.4 the atmospheric pressure on Mars.
In the solid form, there are two allotropes, black powder and black crystals. It has a base centered monoclinic crystal lattice. Helmholtzium's density is approaching 17 g/cm3 and sound travels through it quite fast, approaching 10700 m/s, nearly three times faster than average speed for an element.
Helmholtzium has couple of allotropes. A black amorphous solid forms upon quick solidifcation, while slow solidification can allow black crystals to form. Not all helmholtzium are black, purple helmholtzium also exist as crystalline solid, amorphous solid, or even a liquid.
After filling first four electrons in the ninth shell, there are two filling in the eighth shell in the 8p3/2 orbital. Helmholtzium contains 170 electrons overall in 26 orbitals surrounding the nucleus, where it contains almost all of atom's mass and where most of the component particles reside. The nucleus contains 495 particles
–– 170 protons and 325 neutrons. Helmholtzium atom masses 499.15 daltons, with 99.98% of it is concentrated in its nucleus.
Like every other elements heavier than lead, helmholtzium has no stable isotopes. The most stable isotope is 495Hm with a brief half-life of 3.1 microseconds. It undergoes spontaneous fission, splitting into three lighter nuclei as well as neutrons like the following example.
As with other elements, helmholtzium has meta states, which are excited states of isotopes. The most stable is 497mHm with a half-life of 470 milliseconds, while the second most stable is 499mHm with a half-life of 334 milliseconds.
Helmholtzium is assumed to behave chemically like livermorium and polonium, but because its electron configuration unique to lighter cogeners due to relativistic effects, it may not behave like lighter cogeners. Based on its electronegativity and first ionization energy, helmholtzium would behave chemically like selenium and tellurium instead, and this element would be placed between Se and Te in the reactivity series. The two electrons in the 8p3/2 orbital and four in the ninth shell participitate well in bonding and its most common oxidation state is +6 (hexavalent), with +2 (divalent), +4 (tetravalent), and +8 (octavalent) being less common. However, when dissolving, it most commonly forms +2 ions (colorless), followed by +4 (pink), +6 (peach), then +8 (maroon).
This element can involve in complex anions, such as HmF6−
5, and HmCl8−
Helmholtzium would slowly react with fluorine to form helmholtzium hexafluoride (HmF6), reacts with chlorine to form helmholtzium hexachloride (HmCl6), bromine to form helmholtzium tetrabromide (HmBr4), and iodine to form helmholtzium tetraiodide (HmI4). Because there are different oxistates, it can form different species of corresponding halides, like HmF8, HmF4, HmCl4, HmCl2, HmBr2, and HmI2.
An extremely strong base helmholtzium hydroxide (Hm(OH)2) forms when molten helmholtzium reacts with steam, helmholtzium oxide (HmO2) is also formed as a byproduct. The byproduct then reacts with steam to form the most common oxide HmO3 according to the following equations.
- 2 Hm + 2 H2O + O2 → Hm(OH)2 + HmO2 + H2
- HmO2 + H2O → HmO3 + H2
Helmholtzium can form compounds besides oxides, hydroxide, and halides. Helmholtzium hexahydride (HmH6) is a colorless gas that has a tar-like smell with a condensation point of −20°C and solidifying at −38°C. Helmholtzium disulfide (HmS2) and trisulfide (HmS3) are both light brown powder, though at a little different hues between the two with HmS2 being slightly darker. Helmholtzium dinitride (HmN2) is a lemon yellow powder. Helmholtzium can even form many species of borides, like HmB2, HmB36, and even HmB126.
This black substance can form organic compounds, called organohelmholtzium. An example is tetraethylhelmholtzium ((C2H5)4Hm), as well as simpler diethylhelmholtzium ((C2H5)2Hm).
Occurrence and synthesis Edit
It is almost certain that helmholtzium doesn't exist on Earth at all, but it is believed to exist somewhere in the universe, at least in very tiny amounts. Since every element heavier than lithium were produced by stars, then helmholtzium 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 heavy element. In the universe, only advanced technological civilizations can produce this element, but barely because it requires so much energy to produce this element, thus it is so unstable. An estimated abundance of helmholtzium in the universe by mass is 1.29 × 10−45, which amounts to 4.32 × 107 kilograms.
To go along with other such civilizations, humans on Earth may eventually have the capability to synthesize helmholtzium. To synthesize most stable isotopes of helmholtzium, 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 vast amounts 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 495Hm.