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Symbol Le
Atomic number 154
Pronunciation /'lü•wē•sē•(y)üm/
Named after Gilbert N. Lewis
Name in Saurian Conajaim (Co)
Systematic name Unpentquadium (Upt)
Location on the periodic table
Period 8
Family Erbium family
Series Dumaside series
Coordinate 6f12
Element above Lewisium Fermium
Element left of Lewisium Diracium
Element right of Lewisium Vanthoffium
Atomic properties
Subatomic particles 591
Atomic mass 440.6572 u, 731.7285 yg
Atomic radius 124 pm, 1.24 Å
Covalent radius 133 pm, 1.33 Å
van der Waals radius 179 pm, 1.79 Å
Nuclear properties
Nucleons 437 (154 p+, 283 no)
Nuclear ratio 1.84
Nuclear radius 9.07 fm
Half-life 101.32 ms
Decay mode Spontaneous fission
Decay product Various
Electronic properties
Electron notation 154-8-24
Electron configuration [Og] 5g18 6f11 7d3 8s2 8p2
Electrons per shell 2, 8, 18, 32, 50, 29, 11, 4
Oxidation states 0, +1, +2
(a 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
Physical properties
Bulk properties
Molar mass 440.657 g/mol
Molar volume 31.275 cm3/mol
Density 14.090 g/cm3
Atomic number density 1.37 × 1021 g−1
1.93 × 1022 cm−3
Average atomic separation 373 pm, 3.73 Å
Speed of sound 2087 m/s
Magnetic ordering Paramagnetic
Crystal structure Hexagonal
Color Pale peach
Phase Solid
Thermal properties
Melting point 1744.63 K, 3140.34°R
1471.48°C, 2680.67°F
Boiling point 3100.70 K, 5581.27°R
2827.55°C, 5121.60°F
Liquid range 1356.07 K, 2440.93°R
Liquid ratio 1.78
Triple point 1744.63 K, 3140.34°R
1471.48°C, 2680.67°F
@ 5.5324 Pa, 0.041496 torr
Critical point 7282.94 K, 13109.29°R
7009.79°C, 12649.62°F
@ 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 in the universe
By mass Relative: 7.67 × 10−33
Absolute: 2.57 × 1020 kg
By atom 4.57 × 10−34

Lewisium is the provisional non-systematic name of a theoretical 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 the scientific literature as unpentquadium (Upq), eka-fermium, or simply element 154. Lewisium is the twelfth member of the dumaside series, found in the third row of f-block (below erbium and fermium); this element is located in the periodic table coordinate 6f12.

Atomic properties 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). There are 11 electron occupying the f-orbital and it needs three more to be filled. In addition there are three electrons in the d-orbital one beyond the shell where occupying f-orbital is.

Isotopes Edit

Like every other element heavier than lead, lewisium has no stable isotopes. The longest-lived isotope is 437Le with a half-life of 101.3 milliseconds. It undergoes spontaneous fission, splitting into two or three lighter nuclei plus neutrons like the examples.

Le → 276
Sg + 114
Cd + 47 1
Le → 231
Pa + 114
Cd + 31
P + 61 1

437Le is the only isotope with half-life longer than one millisecond.

Chemical properties and compounds Edit

Lewisium is a noble metal, which means it is a very unreactive metal, even less reactive than gold. It is the least reactive element apart from the noble gases. The most common oxidation states are 0 and +2, while +1 being less common. The lack of reactivity is because lewisium has the highest electronegativity and ionization energy of any metal. The electronegativity on the Pauling scale is 3.18 while the first ionization energy is 13.0 eV, in stark contrast to lighter cogener fermium (6.5 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.

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.

Physical properties 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 and hence 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.

Occurrence Edit

It is almost certain that lewisium 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 lewisium in the universe by mass is 7.67 × 10−33, which amounts to 2.57 × 1020 kilograms.

Synthesis Edit

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 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, 437Le.

Ra + 162
Dy + 49 1
n → 437
Db + 115
In + 50 1
n → 437
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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