# Chemical elements of the eighth period

The eighth period of the extended periodic table of the elements contains all chemical elements that have exactly eight electron shells in the atom . This period is a currently still theoretical continuation of the periods of the periodic table. There is currently no proven chemical element from this period. Theoretically, the innermost (first) electron shell is fully occupied and has two electrons . The second electron shell with eight electrons, the third electron shell with 18 electrons and the fourth electron shell with 32 electrons are also fully occupied. The fifth electron shell has at least 32 electrons and can hold a maximum of 50 electrons. The sixth electron shell has at least 18 electrons and can hold a maximum of 32 electrons. The seventh electron shell has at least 8 electrons and can hold a maximum of 18 electrons. The outermost (eighth) electron shell, also known as the valence shell , can hold between one and eight electrons. Thus there are theoretically a total of 50 chemical elements in the eighth period. According to Glenn T. Seaborg , the chemical elements 122 to 153 are combined to the superactinoids and represent a special group within this period. A special feature of this period is the occupation of the g-orbital with electrons, a g-orbital only occurs in the ground state configuration from this onwards Period on.

## Extract from the extended periodic table

 group 1 2 3 4th 5 6th 7th 8th 9 10 11 12 13 14th 15th 16 17th 18th I. II III IV V VI VII VIII Atomic number  symbol 119 uue 120 Ubn 121 Ubu 122-153 154 Upq 155 Upp 156 Uph 157 oops 158 Upo 159 Upe 160 uhn 161 eagle owl 162 Uhb 163 Uht 164 Uhq 165 Uhp 166 Uhh 167 Uhs 168 Uho Superactinoids ${\ displaystyle {\ Biggl \ {}}$ 122 Ubb 123 Ubt 124 Ubq 125 Ubp 126 Ubh 127 Ubs 128 Ubo 129 exercises 130 Utn 131 Utu 132 sub 133 Utt 134 Utq 135 Utp 136 Uth 137 Uts 138 Uto 139 Ute 140 Uqn 141 equ 142 Uqb 143 Uqt 144 Uqq 145 Uqp 146 Uqh 147 Uqs 148 Uqo 149 Uqe 150 rpn 151 Upu 152 Upb 153 Upt Color legend Unknown Superactinoids

## Chemical and physical properties

The elements of this period are likely to have half-lives in the range of a few nanoseconds. Therefore, the assumed lifespan of an 8th period element is too short to undergo a chemical reaction. In this respect, the elements of the 8th period should not have any defined chemical properties. For the same reason, there should also be no binding forces between the same atoms. From a physical point of view , the period 8 elements would then be gases .

## Magic number

At least two of the period 8 elements, namely 120 ( unbinilium ) and 126 ( unbihexium ) have a magical atomic number . This means that the proton shells in the atom are fully occupied. Since such atoms are energetically more favorable than those with incompletely occupied shells, it is assumed that some isotopes, especially Unbinilium-304 and Unbihexium-310, form islands of stability and therefore have longer half-lives than comparable isotopes of other elements. These two isotopes are doubly magic, which means that in addition to the number of protons, the number of neutrons is also a magic number.

## Number of electrons in the electron shells

The following information is currently still pure theory and can change at any time due to new findings; therefore, they should be treated with extreme caution.

### Superactinoids and the following

Analogous to the 14 transition elements of the 4f block in the sixth period (i.e. Ce - Lu ) and the 14 transition elements of the 5f block in the seventh period (i.e. Th - Lr ) in the eighth period there are a total of 32 transition elements for the 5g - and expect the 6f block. Glenn T. Seaborg coined the term superactinide for these 32 elements, which he assumed to be the ordinal numbers 122–153 , which in German usage is usually represented as superactinoide .

However, the range given by Seaborg should be treated with caution: The electronic configurations of the ground states of the elements 119–164 are e.g. B. in the publication by Nefedov et al. listed. It is noticeable that in 121 and 122 an 8p electron and then a 7d electron are occupied before the first 6f electron is filled in 123 and the first 5g electron in 125. With the alternating filling of 8p, 7d, 6f and 5g, all eighteen 5g electrons are occupied first with element 145 and only then with element 157 all fourteen 6f electrons. Nefedov et al. therefore write "Elements 121–157 can be classified as the period of 5g and 6f electrons."   The term "superactinoids" could thus also be extended to these 37 elements, although the publication mentioned does not use the term superactinoids at any point.

In the case of the other elements of the eighth period, it should be noted that, according to Nefedov, the first 9s electron is already occupied in element 159 in the ground state. In the model by Fricke et al., Which is based on the relativistic Hartree-Fock-Slater calculations. (1971), and the model by Pyykkö (2011), which is based on Dirac-Fock calculations, as in Nefedov, the eighth period ends only with element 172, to which these authors attribute noble gas behavior, but which then already has two 9s and two 9p electrons are occupied.

### Overview

The table below shows with an orange background which electron orbitals should be filled in the eighth period according to the structure principle . The column "Total" indicates the number of electrons that can be found in this shell, even if these are not yet filled in the electronic configuration of the ground state of the elements of the eighth period. This includes in particular the higher orbitals (h, i and j orbital).

The numbers highlighted in green indicate how many electrons of the respective shell are filled in the eighth period, but not the sequence within the period: the expected filling sequence begins with the two electrons from 8s, followed by an 8p (and probably) one 7p, before the next 6f and then 5g electrons are filled. See the electron configurations in the list of elements of the eighth period below.

Electron
shell
Number of electrons comment
s orbital p orbital d orbital f orbital g orbital All in all up to the 7th period 8th period
1 2 - - - - 2 2 2 innermost electron shell
2 2 6th - - - 8th 8th 8th
3 2 6th 10 * - - 18th 18th 18th * the 3d orbital is only filled in the 4th period with the transition metals .
4th 2 6th 10 14 ** - 32 32 32 ** the 4f orbital is only filled in the 6th period with the lanthanides .
5 2 6th 10 14th 0 to 18+ 50 32 32 to 50+ + the 5g orbital is filled with the super actionoids
6th 2 6th 10 0 to 14 ++ - 72 18th 18 to 32 ++ ++ the 6f orbital is filled with the super actionoids
7th 2 6th 0 to 10 - - 98 8th 8 to 18
8th 1 to 2 0 to 6 - - - 118 - 1 to 8 outermost electron shell, valence shell of the eighth period

## list

Since there is still no proven chemical element of the 8th period, all names and symbols are only preliminary. They correspond to the IUPAC rules for systematic element names . The following information is currently still pure theory and can change at any time due to new findings, so they should be treated with extreme caution.

Atomic number symbol Surname Electron configuration
in the ground state
119 Uue Ununennium [ Og ] 8s 1
120 Ubn Unbinilium [Og] 8s 2
121 Ubu Unbiunium [Og] 8p 1 8s 2
122 Ubb Unbibium [Og] 7d 1 8p 1 8s 2
123 Practices Unbitrium [Og] 6f 2 8p 1 8s 2 or
[Og] 6f 1 7d 1 8p 1 8s 2
124 Ubq Unbiquadium [Og] 6f 2 8p 2 8s 2 or
[Og] 6f 3 8p 1 8s 2
125 Ubp Unbipentium [Og] 5g 1 6f 3 8p 1 8s 2
126 Ubh Unbihexium [Og] 5g 2 6f 2 7d 1 8p 1 8s 2
127 Ubs Unbiseptium [Og] 5g 3 6f 2 8p 2 8s 2
128 Ubo Unbioctium [Og] 5g 4 6f 2 8p 2 8s 2
129 Ube Unbiennium [Og] 5g 4 6f 3 7d 1 8p 1 8s 2 or
[Og] 5g 5 6f 2 8p 2 8s 2
130 Utn Untrinilium [Og] 5g 5 6f 3 7d 1 8p 1 8s 2 or
[Og] 5g 6 6f 2 8p 2 8s 2
131 Utu Untriunium [Og] 5g 7 6f 2 8p 2 8s 2
132 Utb Untribium
133 Utt Untritrium
134 Utq Untriquadium
135 Utp Untripentium
136 Uth Untrihexium
137 Uts Untriseptium
138 Uto Untrioctium
139 Ute Untriennium
140 Uqn Unquadnilium
141 Uqu Unquadunium
142 Uqb Unquadbium
143 Uqt Unquadtrium
144 Uqq Unquadquadium
145 Uqp Unquadpentium [Og] 5g 18 6f 3 7d 2 8p 2 8s 2
146 Uqh Unquadhexium
147 Uqs Unquadseptium
148 Uqo Unquadoctium
149 Uqe Unquadennium
150 Upn Unpentnilium
151 Upu Unpentunium
152 Upb Unpentbium
153 Upt Unpenttrium
154 Upq Unpentquadium
155 Upp Unpentium
156 Uph Unpenthexium [Og] 5g 18 6f 13 7d 3 8p 2 8s 2 or
[Og] 5g 18 6f 14 7d 2 8p 2 8s 2
157 Oops Unpentseptium [Og] 5g 18 6f 14 7d 3 8p 2 8s 2
158 Upo Unpentoctium
159 Upe Unpentennium
160 Uhn Unhexnilium
161 Eagle owl Unhexunium
162 Uhb Unhexbium
163 Uht Unhextrium
164 Uhq Non-hexquadium
165 Uhp Unhexpentium
166 Uhh Unhexhexium
167 Uhs Unhexseptium
168 Uho Unhexoctium

## Trivia

In the Star Trek universe , elements 121 and 145 are known as Tritanium and Duranium, respectively. With Edmond Hamilton element 144 develops its own consciousness and becomes a danger for its producer. (See list of invented elements, materials, isotopes and elementary particles )

## Individual evidence

1. ^ Glenn T. Seaborg: Prospects for Further Considerable Extension of the Periodic Table . In: Journal of Chemical Education . tape 46 , October 1969, p. 626-634 . Also found as a reprint in GT Seaborg: Prospects for Further Considerable Extension of the Periodic Table . In: GT Seaborg (Ed.): Modern Alchemy: Selected Papers of Glenn T. Seaborg . World Scientific, 1994, ISBN 978-981-02-1440-1 ( limited preview in Google Book Search).
2. Seaborg's designation and element range is also used in the following book: DC Hofman, DA Shaughnessy: Superheavy Elements . In: Attila Vértes et al. (Ed.): Handbook of Nuclear Chemistry . 2nd Edition. Springer Science & Business Media, 2010, ISBN 978-1-4419-0719-6 ( limited preview in Google book search).
3. V.I. Nefedov, MB Trzhaskovskaya, VG Yarzhemskii: Electronic Configurations and the Periodic Table for Superheavy Elements . In: Doklady Physical Chemistry . tape 408 , no. 2 , 2006, p. 149–151 , doi : 10.1134 / S0012501606060029 ( copy on Russian website [PDF; 111 kB ; accessed on July 11, 2020]).
4. Fricke, B., Greiner, W. and Waber, JT: The continuation of the periodic table up to Z = 172. The chemistry of superheavy elements . In: Theoret. Chim. Acta . tape 21 , 1971, p. 235-260 , doi : 10.1007 / BF01172015 .
5. Pekka Pyykkö: A suggested Periodic Table up to Z ≤ 172, based on Dirac-Fock calculations on atoms and ions . In: Phys. Chem. Chem. Phys. tape 13 , no. 1 , 2011, p. 161–168 , doi : 10.1039 / C0CP01575J ( preprint version from the author's homepage [PDF; 164 kB ; accessed on July 13, 2020]).
6. D.B. Man: Prognozirovanie v uchenii o periodichnosti (Prediction of Periodicity) . In: Nauka . 1976, p. 161–201 (The values ​​can be viewed in VI Nefedov et al. "Electronic Configurations and the Periodic Table for Superheavy Elements" ).
7. Elements and Alloys - Tritanium. In: memory-alpha.fandom.com. Retrieved August 1, 2020 .
8. Elements and Alloys - Duranium. In: memory-alpha.fandom.com. Retrieved August 1, 2020 .

## literature

• J. Huheey: Inorganische Chemie , 2nd edition, 1995.