Actinide

The actinide or actinoid (IUPAC nomenclature) series encompasses the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium.

The actinide series derives its name from the group 3 element actinium. All but one of the actinides are f-block elements, corresponding to the filling of the 5f electron shell; lawrencium, a d-block element, is also generally considered an actinide. In comparison with the lanthanides, also mostly f-block elements, the actinides show much more variable valence.

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Of the actinides, primordial thorium and uranium occur naturally in substantial quantities and small amounts of persisting natural plutonium have also been identified. The radioactive decay of uranium produces transient amounts of actinium and protactinium, and atoms of neptunium, americium, curium, berkelium and californium are occasionally produced from transmutation reactions in uranium ores. The other actinides are purely synthetic elements. Nuclear weapons tests have released at least six actinides heavier than plutonium into the environment; analysis of debris from a 1952 hydrogen bomb explosion showed the presence of americium, curium, berkelium, californium, einsteinium and fermium.

All actinides are radioactive and release energy upon radioactive decay; naturally occurring uranium and thorium, and synthetically produced plutonium are the most abundant actinides on Earth. These are used in nuclear reactors and nuclear weapons. Uranium and thorium also have diverse current or historical uses, and americium is used in the ionization chambers of most modern smoke detectors.

In presentations of the periodic table, the lanthanides and the actinides are customarily shown as two additional rows below the main body of the table, with placeholders or else a selected single element of each series (either lanthanum or lutetium, and either actinium or lawrencium, respectively) shown in a single cell of the main table, between barium and hafnium, and radium and rutherfordium, respectively. This convention is entirely a matter of aesthetics and formatting practicality; a rarely used wide-formatted periodic table inserts the lanthanide and actinide series in their proper places, as parts of the table's sixth and seventh rows (periods).

Read more about Actinide:  Discovery, Isolation and Synthesis, Isotopes, Distribution in Nature, Extraction, Properties, Applications, Toxicity

Other articles related to "actinide, actinides":

Actinide - Toxicity
... Using actinides in nuclear fuel, sealed radioactive sources or advanced materials such as self-glowing crystals has many potential benefits ... However, a serious concern is the extremely high radiotoxicity of actinides and their migration in the environment ... Use of chemically unstable forms of actinides in MOX and sealed radioactive sources is not appropriate by modern safety standards ...
Period 7 Element - Elements
... Transition metals Post-transition metals Other nonmetals Halogens Noble gases Lanthanides Actinides Color of the atomic number shows state of matter (at standard conditions 0 °C ...
Thorium Fuel Cycle - Nuclear Reactions With Thorium - Fission Product Wastes
... According to some toxicity studies, the thorium cycle can fully recycle actinide wastes and only emit fission product wastes, and after a few hundred years, the waste from a ... Other studies assume some actinide losses and find that actinide wastes dominate thorium cycle waste radioactivity at some future periods ...
Actinide Concept
... The actinide concept in nuclear chemistry was first theorized by Glenn T ... periodic table of the elements by placing a new actinide series, for elements 89–103, below the lanthanide series ...
Bk - Characteristics - Physical
... Berkelium is a soft, silvery-white, radioactive actinide metal ... In the periodic table, it is located to the right of the actinide curium, to the left of the actinide californium and below the lanthanide terbium with which it shares many similarities in ... Berkelium is relatively soft and has one of the lowest bulk moduli among the actinides, at about 20 GPa (2×1010Pa) ...
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