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==History== |
==History== |
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Elements beyond the |
Elements beyond the were first proposed to exist as early as 1895, when Danish chemist [[Hans Peter Jørgen Julius Thomsen]] predicted that [[thorium]] and [[uranium]] formed part of a 32-element period which would end at a chemically inactive element with atomic weight 292 (not far from the 294 for the only known isotope of [[oganesson]]). In 1913, Swedish physicist [[Johannes Rydberg]] similarly predicted that the next noble gas after [[radon]] would have atomic number 118, and purely formally derived even heavier congeners of radon at ''Z'' = 168, 218, 290, 362, and 460, exactly where the [[Aufbau principle]] would predict them to be. [[Niels Bohr]] predicted in 1922 the electronic structure of this next [[noble gas]] at ''Z'' = 118, and suggested that the reason why elements beyond uranium were not seen in nature was because they were too unstable. The German physicist and engineer Richard Swinne published a review paper in 1926 containing predictions on the [[transuranic element]]s (he may have coined the term) in which he anticipated modern predictions of an [[island of stability]]: he first hypothesised in 1914 that half-lives should not decrease strictly with atomic number, but suggested instead that there might be some longer-lived elements at ''Z'' = 98–102 and ''Z'' = 108–110, and speculated that such elements might exist in the [[Earth's core]], in [[iron meteorites]], or in the [[Greenland ice sheet|ice caps of Greenland]] where they had been locked up from their supposed cosmic origin.<ref>{{cite book |last=Kragh |first=Helge |date=2018 |title=From Transuranic to Superheavy Elements: A Story of Dispute and Creation |publisher=Springer |pages=6–10 |isbn=9783319758138}}</ref> By 1955, these elements were called ''superheavy'' elements.<ref name=Transuraniumppl /> |
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The first predictions on properties of undiscovered superheavy elements were made in 1957, when the concept of [[nuclear shell model|nuclear shells]] was first explored and an island of stability was theorized to exist around element 126.<ref name=fossilfission /> In 1967, more rigorous calculations were performed, and the island of stability was theorized to be centered at the then-undiscovered [[flerovium]] (element 114); this and other subsequent studies motivated many researchers to search for superheavy elements in nature or attempt to [[synthetic element|synthesize]] them at accelerators.<ref name=Transuraniumppl /> Many searches for superheavy elements were conducted in the 1970s, all with negative results. {{As of|2022|4}}, synthesis has been attempted for every element up to and including unbiseptium (''Z'' = 127), except unbitrium (''Z'' = 123),<ref name="emsley" /><ref name=beyonduranium /><ref name=superlourds /> with the heaviest successfully synthesized element being [[oganesson]] in 2002 and the most recent discovery being that of [[tennessine]] in 2010.<ref name="emsley" /> |
The first predictions on properties of undiscovered superheavy elements were made in 1957, when the concept of [[nuclear shell model|nuclear shells]] was first explored and an island of stability was theorized to exist around element 126.<ref name=fossilfission /> In 1967, more rigorous calculations were performed, and the island of stability was theorized to be centered at the then-undiscovered [[flerovium]] (element 114); this and other subsequent studies motivated many researchers to search for superheavy elements in nature or attempt to [[synthetic element|synthesize]] them at accelerators.<ref name=Transuraniumppl /> Many searches for superheavy elements were conducted in the 1970s, all with negative results. {{As of|2022|4}}, synthesis has been attempted for every element up to and including unbiseptium (''Z'' = 127), except unbitrium (''Z'' = 123),<ref name="emsley" /><ref name=beyonduranium /><ref name=superlourds /> with the heaviest successfully synthesized element being [[oganesson]] in 2002 and the most recent discovery being that of [[tennessine]] in 2010.<ref name="emsley" /> |
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Fricke et al.'s format is more focused on formal electron configurations than likely chemical behaviour. They place elements 156–164 in groups 4–12 because formally their configurations should be 7d<sup>2</sup> through 7d<sup>10</sup>. However, they differ from the previous d-elements in that the 8s shell is not available for chemical bonding: instead, the 9s shell is. Thus element 164 with 7d<sup>10</sup>9s<sup>0</sup> is noted by Fricke et al. to be analogous to palladium with 4d<sup>10</sup>5s<sup>0</sup>, and they consider elements 157–172 to have chemical analogies to groups 3–18 (though they are ambivalent on whether elements 165 and 166 are more like group 1 and 2 elements or more like group 11 and 12 elements, respectively). Thus, elements 157–164 are placed in their table in a group that the authors do not think is chemically most analogous.<ref name=actrev>{{cite journal |last1=Fricke |first1=Burkhard |last2=Waber |first2=J. T. |date=1971 |title=Theoretical Predictions of the Chemistry of Superheavy Elements: Continuation of the Periodic Table up to Z{{=}}184 |url=https://kobra.uni-kassel.de/bitstream/handle/123456789/2008100124269/Fricke_theoretical_1971.pdf |journal=Actinides Reviews |volume=1 |issue= |pages=433–485 |doi= |access-date=5 January 2024}}</ref> |
Fricke et al.'s format is more focused on formal electron configurations than likely chemical behaviour. They place elements 156–164 in groups 4–12 because formally their configurations should be 7d<sup>2</sup> through 7d<sup>10</sup>. However, they differ from the previous d-elements in that the 8s shell is not available for chemical bonding: instead, the 9s shell is. Thus element 164 with 7d<sup>10</sup>9s<sup>0</sup> is noted by Fricke et al. to be analogous to palladium with 4d<sup>10</sup>5s<sup>0</sup>, and they consider elements 157–172 to have chemical analogies to groups 3–18 (though they are ambivalent on whether elements 165 and 166 are more like group 1 and 2 elements or more like group 11 and 12 elements, respectively). Thus, elements 157–164 are placed in their table in a group that the authors do not think is chemically most analogous.<ref name=actrev>{{cite journal |last1=Fricke |first1=Burkhard |last2=Waber |first2=J. T. |date=1971 |title=Theoretical Predictions of the Chemistry of Superheavy Elements: Continuation of the Periodic Table up to Z{{=}}184 |url=https://kobra.uni-kassel.de/bitstream/handle/123456789/2008100124269/Fricke_theoretical_1971.pdf |journal=Actinides Reviews |volume=1 |issue= |pages=433–485 |doi= |access-date=5 January 2024}}</ref> |
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Nefedov |
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{{ill|Vadim Nefedov|lt=Nefedov|ru|Нефёдов, Вадим Иванович}}, Trzhaskovskaya, and Yarzhemskii carried out calculations up to 164 (results published in 2006). They considered elements 158 through 164 to be homologues of groups 4 through 10, and not 6 through 12, noting similarities of electron configurations to the period 5 transition metals (e.g. element 159 7d<sup>4</sup>9s<sup>1</sup> vs Nb 4d<sup>4</sup>5s<sup>1</sup>, element 160 7d<sup>5</sup>9s<sup>1</sup> vs Mo 4d<sup>5</sup>5s<sup>1</sup>, element 162 7d<sup>7</sup>9s<sup>1</sup> vs Ru 4d<sup>7</sup>5s<sup>1</sup>, element 163 7d<sup>8</sup>9s<sup>1</sup> vs Rh 4d<sup>8</sup>5s<sup>1</sup>, element 164 7d<sup>10</sup>9s<sup>0</sup> vs Pd 4d<sup>10</sup>5s<sup>0</sup>). They thus agree with Fricke et al. on the chemically most analogous groups, but differ from them in that Nefedov et al. actually place elements in the chemically most analogous groups. Rg and Cn are given an asterisk to reflect differing configurations from Au and Hg (in the original publication they are drawn as being displaced in the third dimension). In fact Cn probably has an analogous configuration to Hg, and the difference in configuration between Pt and Ds is not marked.<ref name=nefedov/> |
{{ill|Vadim Nefedov|lt=Nefedov|ru|Нефёдов, Вадим Иванович}}, Trzhaskovskaya, and Yarzhemskii carried out calculations up to 164 (results published in 2006). They considered elements 158 through 164 to be homologues of groups 4 through 10, and not 6 through 12, noting similarities of electron configurations to the period 5 transition metals (e.g. element 159 7d<sup>4</sup>9s<sup>1</sup> vs Nb 4d<sup>4</sup>5s<sup>1</sup>, element 160 7d<sup>5</sup>9s<sup>1</sup> vs Mo 4d<sup>5</sup>5s<sup>1</sup>, element 162 7d<sup>7</sup>9s<sup>1</sup> vs Ru 4d<sup>7</sup>5s<sup>1</sup>, element 163 7d<sup>8</sup>9s<sup>1</sup> vs Rh 4d<sup>8</sup>5s<sup>1</sup>, element 164 7d<sup>10</sup>9s<sup>0</sup> vs Pd 4d<sup>10</sup>5s<sup>0</sup>). They thus agree with Fricke et al. on the chemically most analogous groups, but differ from them in that Nefedov et al. actually place elements in the chemically most analogous groups. Rg and Cn are given an asterisk to reflect differing configurations from Au and Hg (in the original publication they are drawn as being displaced in the third dimension). In fact Cn probably has an analogous configuration to Hg, and the difference in configuration between Pt and Ds is not marked.<ref name=nefedov/> |
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Greek: Ά ά Έ έ Ή ή Ί ί Ό ό Ύ ύ Ώ ώ Α α Β β Γ γ Δ δ Ε ε Ζ ζ Η η Θ θ Ι ι Κ κ Λ λ Μ μ Ν ν Ξ ξ Ο ο Π π Ρ ρ Σ σ ς Τ τ Υ υ Φ φ Χ χ Ψ ψ Ω ω {{Polytonic|}}
Cyrillic: А а Б б В в Г г Ґ ґ Ѓ ѓ Д д Ђ ђ Е е Ё ё Є є Ж ж З з Ѕ ѕ И и І і Ї ї Й й Ј ј К к Ќ ќ Л л Љ љ М м Н н Њ њ О о П п Р р С с Т т Ћ ћ У у Ў ў Ф ф Х х Ц ц Ч ч Џ џ Ш ш Щ щ Ъ ъ Ы ы Ь ь Э э Ю ю Я я ́
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