A period 7 element is one of the chemical elements in the seventh row (or period) of the periodic table of the elements.
All elements of period 7 are radioactive. This period contains the heaviest element which occurs naturally on earth, uranium. Most of the subsequent elements in the period have been synthesized artificially. Whilst some of these (e.g. plutonium) are now available in tonne quantities, most are extremely rare, having only been prepared in microgram amounts or less. Some of the later elements have only ever been identified in laboratories in quantities of a few atoms at a time.
Although the rarity of many of these elements means that experimental results are not very extensive, periodic and group trends in behaviour appear to be less well defined for period 7 than for other periods. Whilst francium and radium do show typical properties of Groups 1 and 2 respectively, the actinides display a much greater variety of behaviour and oxidation states that than the lanthanides. Initial studies suggest Group 14 element ununquadium appears to be a noble gas instead of a poor metal, and group 18 element ununoctium probably is not a noble gas.[1] These peculiarities of period 7 may be due to a variety of factors, including a large degree of spin-orbit coupling and relativistic effects, ultimately caused by the very high positive electrical charge from their massive atomic nuclei.
The period 7 elements are:
| Group | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| # Name |
87 Fr |
88 Ra |
89-103 | 104 Rf |
105 Db |
106 Sg |
107 Bh |
108 Hs |
109 Mt |
110 Ds |
111 Rg |
112 Cn |
113 Uut |
114 Uuq |
115 Uup |
116 Uuh |
117 Uus |
118 Uuo |
| e--conf. | ||||||||||||||||||
| Actinides | 89 Ac |
90 Th |
91 Pa |
92 U |
93 Np |
94 Pu |
95 Am |
96 Cm |
97 Bk |
98 Cf |
99 Es |
100 Fm |
101 Md |
102 No |
103 Lr |
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| e--conf. | ||||||||||||||||||
Element categories in the periodic table
| Metals | Metalloids | Nonmetals | Unknown chemical properties |
|||||||
| Alkali metals | Alkaline earth metals | Inner transition elements | Transition elements | Other metals | Other nonmetals | Halogens | Noble gases | |||
| Lanthanides | Actinides | |||||||||
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