Period 7 Element - Actinides


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.

<table> 89Ac 90Th 91Pa 92U 93Np 94Pu 95Am 96Cm 97Bk 98Cf 99Es 100Fm 101Md 102No 103Lr

Of the actinides, thorium and uranium occur naturally in substantial, primordial, 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 this topic:  Period 7 Element

Other articles related to "actinides":

MOX Fuel - Current Applications - Fast Reactors
... to favour fission for almost all of the actinides, including 238 92U, fast reactors can use all of them for fuel ... All actinides, including TRU or transuranium actinides can undergo neutron induced fission with unmoderated or fast neutrons ... is more efficient for using plutonium and higher actinides as fuel ...
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Actinides In The Environment
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... Actinides Half-life Fission products Cm Puƒ Cf Ac№ 10–22 y m is meta Kr Cd₡ Uƒ Pu Cmƒ 29–90 y Cs Sr Sm₡ Sn ƒ for fissile Cfƒ Amƒ Cfƒ 140 y – 1.6 ky No fission ...
Nuclear Reprocessing - Separation Technologies - Pyroprocessing
... It can separate many or even all actinides at once and produce highly radioactive fuel which is harder to manipulate for theft or making nuclear weapons ... weapons, and it also leaves the minor actinides (americium and curium) behind, producing waste with more long-lived radioactivity ... use of the nuclear fuel is produced by the actinides, since there are no fission products with half-lives in this range ...