Actinide

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Actinide

According to IUPAC nomenclature

IUPAC nomenclature

IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general. It is developed and kept up to date under the auspices of the International Union of Pure and Applied Chemistry ....
, the actinoid (previously actinide) series encompasses the 15 chemical element

Chemical element

A chemical element is a type of atom that is distinguished by its atomic number; that is, by the number of protons in its atomic nucleus. The term is also used to refer to a pure chemical Chemical substance composed of atoms with the same number of protons....
s that lie between actinium

Actinium

Actinium is a radioactive chemical element with the symbol Ac and atomic number 89, which was discovered in 1899. It was the first Primordial element to be isolated, although polonium, radium and radon were observed before, but not isolated until 1902....
and lawrencium

Lawrencium

Lawrencium is a radioactive synthetic element with the symbol Lr and atomic number 103.Its most stable known isotope is 262Lr, with a half-life of approximately 3.6 hours....
included on the periodic table

Periodic table

Atomic number

In chemistry and physics, the atomic number is the number of protons found in the atomic nucleus of an atom. It is conventionally represented by the symbol Z....
s 89 - 103.

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Encyclopedia

Atomic No. Atomic number In chemistry and physics, the atomic number is the number of protons found in the atomic nucleus of an atom. It is conventionally represented by the symbol Z....	Name Chemical element A chemical element is a type of atom that is distinguished by its atomic number; that is, by the number of protons in its atomic nucleus. The term is also used to refer to a pure chemical Chemical substance composed of atoms with the same number of protons....	Symbol Chemical symbol A chemical symbol is an abbreviation or shortened version of the name of a chemical element, generally assigned in relation to its Latin language name....
89	Actinium Actinium Actinium is a radioactive chemical element with the symbol Ac and atomic number 89, which was discovered in 1899. It was the first Primordial element to be isolated, although polonium, radium and radon were observed before, but not isolated until 1902....	Ac
90	Thorium Thorium Thorium is a chemical element with the symbol Th and atomic number 90. As a naturally occurring, slightly radioactive metal, it has been considered as an alternative nuclear fuel to uranium....	Th
91	Protactinium Protactinium Protactinium is a chemical element with the symbol Pa and atomic number 91. Its longest-lived isotope has a half-life of 32,760 years....	Pa
92	Uranium Uranium Uranium is a silvery-gray metallic chemical element in the actinide series of the periodic table that has the chemical symbol U and atomic number 92....	U
93	Neptunium Neptunium Neptunium is a chemical element with the symbol Np and atomic number 93. A radioactivity metallic element, neptunium is the first transuranic element and belongs to the actinide series....	Np
94	Plutonium Plutonium Plutonium is a rare transuranic radioactive chemical element. It is an actinide metal of silvery-white appearance that tarnishes when exposed to air, forming a dull coating when plutonium oxide....	Pu
95	Americium Americium Americium is a synthetic element that has the symbol Am and atomic number 95. A radioactive decay metallic element, americium is an actinide that was obtained in 1944 by Glenn T....	Am
96	Curium Curium Curium is a synthetic element with the symbol Cm and atomic number 96. A Radioactive decay metallic transuranic element of the actinide series, curium is produced by bombarding plutonium with alpha particles and was named for Maria Sklodowska-Curie and her husband Pierre Curie....	Cm
97	Berkelium Berkelium Berkelium is a synthetic element with the symbol Bk and atomic number 97. A radioactive metallic element in the actinide series, berkelium was first synthesized by bombarding americium with alpha particles and was named after the University of California, Berkeley....	Bk
98	Californium Californium Californium is a metallic chemical element with the symbol Cf and atomic number 98. A Radioactive decay transuranic element, californium is used in starting nuclear reactors, optimizing coal-fired power plants and cement production facilities , medical treatment of cancer, and oil exploration via down hole well logging....	Cf
99	Einsteinium Einsteinium Einsteinium is a metallic synthetic element. On the periodic table, it is represented by the symbol Es and atomic number 99. It is the seventh transuranic element, and seventh in the series of actinoids....	Es
100	Fermium Fermium Fermium is a synthetic element with the symbol Fm and atomic number 100. A highly radioactive metallic transuranic element of the actinide series, fermium is made by bombarding plutonium with neutrons and is named after nuclear physicist Enrico Fermi....	Fm
101	Mendelevium Mendelevium Mendelevium is a synthetic element with the symbol Md and the atomic number 101. A metallic radioactive transuranic element of the actinides, mendelevium is synthesized by bombarding einsteinium with alpha particles and was named after Dmitri Mendeleev, who was responsible for the Periodic Table....	Md
102	Nobelium Nobelium Nobelium is a synthetic element with the symbol No and atomic number 102. It was first correctly identified in 1956 by scientists at the Flerov Laboratory of Nuclear Reactions in Dubna, Russia....	No
103	Lawrencium Lawrencium Lawrencium is a radioactive synthetic element with the symbol Lr and atomic number 103.Its most stable known isotope is 262Lr, with a half-life of approximately 3.6 hours....	Lr

According to IUPAC nomenclature

IUPAC nomenclature

Chemical element

Actinium

Lawrencium

Periodic table

Atomic number

In chemistry and physics, the atomic number is the number of protons found in the atomic nucleus of an atom. It is conventionally represented by the symbol Z....
s 89 - 103. The actinoid series derives its name from the first element in the series, actinium, and ultimately from the Greek a?t?? (aktis), "ray," reflecting the elements' radioactivity.

The actinoid series (An) is included in some definitions of the rare earth elements. IUPAC is currently recommending the name actinoid rather than actinide, as the suffix "-ide" generally indicates ion

Ion

An ion is an atom or molecule which has lost or gained one or more electrons, giving it a positive or negative electrical charge. According to the Bohr_model this will be from or in the outer shield 'n'....
s (moreover, from Greek, the suffix -ide means "sons of actinium", while -oid means "similar to actinium"). There are alternative arrangements of the periodic table that exclude actinium or lawrencium from appearing together with the other actinoids.

The actinoids display less similarity in their chemical properties than the lanthanoid series (Ln), exhibiting a wider range of oxidation states, which initially led to confusion as to whether actinium, thorium, and uranium should be considered d-block elements. All actinoids are radioactive

Radioactive decay

Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting ionizing particles and radiation. This decay, or loss of energy, results in an atom of one type, called the parent nuclide transforming to an atom of a different type, called the daughter nuclide....
.

Only thorium and uranium occur naturally in the earth's crust in anything more than trace quantities. Neptunium and plutonium have been known to show up naturally in trace amounts in uranium ores as a result of decay or bombardment. The remaining actinoids were discovered in nuclear fallout, or were synthesized in particle colliders. The latter half of the series possess exceedingly short half-lives

Half-life

The half-life of a quantity whose value decreases with time is the interval required for the quantity to decay to half of its initial value. The concept originated in describing how long it takes atoms to undergo radioactive decay but also applies in a wide variety of other situations....
.

The actinoids are typically placed below the main body of the periodic table (below the lanthanoid series), in the manner of a footnote. The full-width version of the periodic table

Periodic table (wide)

This is a version of the periodic table of the elements that places all elements of one period in the same row. For more information on its contents and history, see the article Periodic table....
shows the position of the actinoids more clearly.

An organometallic compound of an actinoid is known as an organoactinoid.

History of the actinoid series

From the earlier known chemical properties of actinium (89) up to uranium (92), indicating a relation to the transition metal

Transition metal

In chemistry, the term transition metal has two possible meanings:*It commonly refers to any element in the d-block of the periodic table, including the group 12 element elements zinc, cadmium and Mercury ....
s, it was generally assumed that the transuraniums would have similar qualities. During his Manhattan Project

Manhattan Project

The Manhattan Project was the project to develop the first atomic weapon during World War II; involving the United States, the United Kingdom, and Canada....
research in 1944, Glenn T. Seaborg

Glenn T. Seaborg

Glenn Theodore Seaborg was an American scientist who won the 1951 Nobel Prize in Chemistry for "discoveries in the chemistry of the transuranic element," contributed to the discovery and isolation of ten elements, developed the actinide concept and was the first to propose the actinide series which led to the current arrangement of the Perio...
experienced unexpected difficulty isolating americium (95) and curium (96). He began wondering if these elements more properly belonged to a different series than the transition metals, which would explain why the expected chemical properties of the new elements were different. In 1945, he went against the advice of colleagues and proposed the most significant change to Mendeleev's periodic table

Periodic table

The periodic table of the chemical elements is a table method of displaying the chemical elements. Although precursors to this table exist, its invention is generally credited to Russian chemist Dmitri Mendeleev in 1869....
to have been accepted universally by the scientific community: the actinide series.

In 1945, Seaborg published his actinide concept

Actinide concept

The actinide concept in nuclear chemistry was first theorized by Glenn T. Seaborg in 1944, resulting in the correction of Dmitri Mendeleev's periodic table of the elements by placing a new actinide series below the lanthanide series....
of heavy element electronic structure, predicting that the actinoids would form a transition series analogous to the rare earth series of lanthanoid elements.

In 1961, Antoni Przybylski discovered a star

Przybylski's star

Przybylski's Star is a peculiar star that is located about 410 light years from the Sun in the constellation Centaurus.In 1961, the Polish-Australian astronomer Antoni Przybylski discovered that this star had a peculiar spectrum that would not fit into the standard framework for stellar classification....
that contained unusually high amounts of actinoids.

Actinide

History of the actinoid series

See also

External links