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Lewisium

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Lewisium (154Le)
Nomenclature
Pronunciation /'lü•wē•sē•(y)üm/
Name in Saurian Conajaim (Co)
/'cō•näsh•ām/
Systematic name Unpentquadium (Upt)
/'ün•pent•kwo•dē•(y)üm/
Location on the periodic table
Period 8
Coordinate 6f14
Above element Nobelium (102No)
Below element ––
Previous element Diracium (153Dr)
Next element Vanthoffium (155Vh)
Family Ytterbium family
Series Dumaside series
Atomic properties
Atomic mass 440.6572 u, 731.7285 yg
Atomic radius 124 pm, 1.24 Å
Van der Waals radius 179 pm, 1.79 Å
Subatomic particles 591
Nuclear properties
Nucleons 437 (154 p+, 283 n0)
Nuclear ratio 1.84
Nuclear radius 9.07 fm
Half-life 53.588 s
Electronic properties
Electron notation 154-8-24
Electron configuration [Mc] 5g18 6f12 7d2 8s2 8p2
2, 8, 18, 32, 50, 30, 10, 4
Oxidation states 0, +1, +2
(mildly basic oxide)
Electronegativity 3.18
First ionization energy 1257.8 kJ/mol, 13.036 eV
Electron affinity 8.5 kJ/mol, 0.088 eV
Covalent radius 133 pm, 1.33 Å
Physical properties
Bulk properties
Molar mass 440.657 g/mol
Molar volume 31.275 cm3/mol
Density 14.090 g/cm3
Atomic number density 1.93 × 1022 cm−3
Average atomic separation 373 pm, 3.73 Å
Speed of sound 2087 m/s
Magnetic ordering Paramagnetic
Crystal structure Simple hexagonal
Color Pale peach
Phase Solid
Thermodynamics
Melting point 1744.63 K, 1471.48°C
2680.67°F, 3140.34°R
Boiling point 3100.70 K, 2827.55°C
5121.60°F, 5581.27°R
Liquid range 1356.07 K/°C, 2440.93°F/°R
Liquid ratio 1.78
Triple point 1744.63 K, 1471.48°C
2680.67°F, 3140.34°R
@ 5.5324 Pa, 0.041496 torr
Critical point 7282.94 K, 7009.79°C
12649.62°F, 13109.29°R
@ 177.9524 MPa, 1756.259 atm
Heat of fusion 18.441 kJ/mol
Heat of vaporization 301.193 kJ/mol
Heat capacity 0.05048 J/g/K, 0.09087 J/g/°R
22.245 J/mol/K, 40.041 J/mol/°R
Abundance
Universe (by mass) Relative: 7.67 × 10−37
Absolute: 2.57 × 1016 kg

Lewisium is the fabricated name of a hypothetical element with the symbol Le and atomic number 154. Lewisium was named in honor of Gilbert N. Lewis (1875–1946), who discovered covalent bond, reformulate chemical dynamics, and developed theory of Lewis acids and bases; he also coined "photon" and explained phosphorescence. This element is known in scientific literature as unpentquadium (Upq), eka-nobelium, or simply element 154. Lewisium 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 periodic table coordinate 6f14.

Properties Edit

Physical Edit

Lewisium is a shiny pale peach metal that does not darken when exposed to air; it is ductile and malleable twice as dense as zinc with a value of over 14 g/cm3. Lewisium atoms together form hexagonal crystal lattices that upon heating it transforms to face centered cubic at 479°C and to body centered cubic at 901°C. Atoms that make up lattices are separated by an average of 373 pm from each other.

Lewisium liquifies at 1471°C (heat of fusion: 18.44 kJ/mol) and vaporizes at 2828°C (heat of vaporization: 301.19 kJ/mol). Its corresponding liquid range is 1.78, obtained by dividing these two values but they have to be converted to kelvins by adding 273 to each number first since Celsius scale is not the absolute temperature scale. Because the boiling point depends on pressure, different pressure would result in different boiling point so is liquid ratio. If ambient pressure is lower, its boiling point would correspondingly be lower. If pressure is low enough, boiling point would equal its melting point, called its triple point, this occurs at a pressure of 5.53 Pa, only 118300 of that of Earth's sea level pressure and 0.87% the atmospheric pressure on Mars. The critical point is on the opposite corner of the phase diagram as its triple point; for lewisium, this occurs at 7010°C under a 178 MPa pressure, 1756 times greater than Earth's and 19 times the surface pressure on Venus.

Atomic Edit

Lewisium atom has 24 orbitals in 8 shells of 154 electrons surrounding the nucleus containing 437 nucleons and a 1.84 ratio (154 protons, 283 neutrons). Since lewisium marks the last element of the f-block series, the f-orbital should be filled with 14 electrons, but due to spin-orbit coupling due to relativistic effects, there are just 12 and it needs two more. Instead there are two in the d-orbital one beyond the shell where occupying f-orbital is.

Isotopes Edit

Like every other elements heavier than lead, lewisium has no stable isotopes. The most stable isotope is 437Le with a half-life of 53.6 seconds. It undergoes spontaneous fission, splitting into two or three lighter nuclei as well as neutrons like the following examples.

437
154
Le → 276
106
Sg + 114
48
Cd + 47 1
0
n
437
154
Le → 231
91
Pa + 114
48
Cd + 31
15
P + 61 1
0
n

437Le is the only isotope with half-life longer than one second as every other isotope have half-lives less than 400 milliseconds.

Chemical Edit

Lewisium is a noble metal, which means it is a very unreactive metal, even less reactive than gold. It is considered the least reactive element. The most common oxidation state is obviously zero, while +1 and +2 are less common. The lack of reactivity is due to filled g- and f-orbitals as well as full p1/2 orbital. The electronegativity on the Pauling scale is 2.98 while the first ionization energy is 13.4 eV, much higher than lighter cogener nobelium (6.65 eV). Such a high electronegativity means it can accept electrons from other atoms but it can't because of the energy shielding effect caused by incompleted f-orbital. It can form metal-nonmetal covalent bonds like is typical of internonmetallic compounds, instead of polar or ionic bonds typical of metal-nonmetal compounds.

Compounds Edit

There are interesting compounds of lewisium, such as lewisium(II) oxide (LeO), which is a dark yellow crystalline substance, and lewisium(II) carbide (Le2C), which has the melting point of 5318°C (9604°F), just below the surface temperature of our Sun. Lewisium halides include LeF, LeF2, LeCl, and LeCl2, all of which are white ionic solids except for LeCl2, which is pale yellow.

Occurrence and synthesis Edit

It is almost certain that lewisium 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 lewisium 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. Instead, this element virtually can only be made by advanced technological civilizations. An estimated abundance of lewisium in the universe by mass is 7.67 × 10−37, which amounts to 2.57 × 1016 kilograms.

To go along with other such civilizations, humans on Earth may eventually have the capability to synthesize lewisium. To synthesize most stable isotopes of lewisium, 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 437Le.

226
88
Ra + 162
66
Dy + 49 1
0
n → 437
154
Le
272
105
Db + 115
49
In + 50 1
0
n → 437
154
Le
Periodic table
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 Bc Fl Lz Lv J Mc
8 Nw Gl * Du Bu Ab Sh Hi Da Bo Fa Av So Hr Wt Dr Le Vh Hk Ke Ap Vw Hu Fh Ma Kp Gb
9 Ps Hb Kf Bn Ju Hm Bs Rs
* Ls Dm Ms Ts Dt Mw Pk By Bz Fk Dw To Pl Ah My Cv Fy Ch An Ed
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