The actinide (or actinoid) series encompasses the 15 chemical elements that lie between actinium and lawrencium on the periodic table, with atomic numbers 89 - 103^[1]. The actinide series derives its name from the first element in the series, actinium. See also: List of elements by atomic number In chemistry and physics, the atomic number (also known as the proton number) is the number of protons found in the nucleus of an atom. ... The periodic table of the chemical elements A chemical element, or element, is a type of atom that is defined by its atomic number; that is, by the number of protons in its nucleus. ... General Name, Symbol, Number actinium, Ac, 89 Chemical series actinides Group, Period, Block 3, 7, f Appearance silvery Standard atomic weight (227) g·mol−1 Electron configuration [Rn] 6d1 7s2 Electrons per shell 2, 8, 18, 32, 18, 9, 2 Physical properties Phase solid Density (near r. ... General Name, Symbol, Number thorium, Th, 90 Chemical series Actinides Group, Period, Block n/a, 7, f Appearance silvery white Standard atomic weight 232. ... General Name, Symbol, Number protactinium, Pa, 91 Chemical series actinides Group, Period, Block n/a, 7, f Appearance bright, silvery metallic luster Standard atomic weight 231. ... This article is about the chemical element. ... General Name, Symbol, Number neptunium, Np, 93 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery metallic Standard atomic weight (237) g·mol−1 Electron configuration [Rn] 5f4 6d1 7s2 Electrons per shell 2, 8, 18, 32, 22, 9, 2 Physical properties Phase solid Density (near r. ... This article is about the radioactive element. ... General Name, Symbol, Number americium, Am, 95 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery white sometimes yellow Standard atomic weight (243) g·mol−1 Electron configuration [Rn] 5f7 7s2 Electrons per shell 2, 8, 18, 32, 25, 8, 2 Physical properties Phase solid Density (near... General Name, Symbol, Number curium, Cm, 96 Chemical series actinides Group, Period, Block ?, 7, f Appearance silvery Atomic mass (247) g/mol Electron configuration [Rn] 5f7 6d1 7s2 Electrons per shell 2, 8, 18, 32, 25, 9, 2 Physical properties Phase solid Density (near r. ... General Name, Symbol, Number berkelium, Bk, 97 Chemical series actinides Group, Period, Block n/a, 7, f Appearance unknown, probably silvery white or metallic gray Atomic mass (247) g·mol−1 Electron configuration [Rn] 5f9 7s2 Electrons per shell 2, 8, 18, 32, 27, 8, 2 Physical properties Phase solid... General Name, Symbol, Number californium, Cf, 98 Chemical series actinides Group, Period, Block n/a, 7, f Appearance unknown, probably silvery white or metallic gray Atomic mass (251) g·mol−1 Electron configuration [Rn] 5f10 7s2 Electrons per shell 2, 8, 18, 32, 28, 8, 2 Physical properties Phase solid... General Name, Symbol, Number einsteinium, Es, 99 Chemical series actinides Group, Period, Block n/a, 7, f Appearance unknown, probably silvery white or metallic gray Standard atomic weight (252) g·mol−1 Electron configuration [Rn] 5f11 7s2 Electrons per shell 2, 8, 18, 32, 29, 8, 2 Physical properties Phase... General Name, Symbol, Number fermium, Fm, 100 Chemical series actinides Group, Period, Block n/a, 7, f Appearance unknown, probably silvery white or metallic gray Atomic mass (257) g·mol−1 Electron configuration [Rn] 5f12 7s2 Electrons per shell 2, 8, 18, 32, 30, 8, 2 Physical properties Phase solid... General Name, Symbol, Number mendelevium, Md, 101 Chemical series actinides Group, Period, Block n/a, 7, f Appearance unknown, probably silvery white or metallic gray Atomic mass (258) g·mol−1 Electron configuration [Rn] 5f13 7s2 Electrons per shell 2, 8, 18, 32, 31, 8, 2 Physical properties Phase solid... General Name, Symbol, Number nobelium, No, 102 Chemical series actinides Group, Period, Block n/a, 7, f Appearance unknown, probably silvery white or metallic gray Atomic mass (259) g/mol Electron configuration [Rn] 5f14 7s2 Electrons per shell 2, 8, 18, 32, 32, 8, 2 Physical properties Phase solid Melting... General Name, Symbol, Number lawrencium, Lr, 103 Chemical series actinides Group, Period, Block n/a, 7, d Appearance unknown, probably silvery white or metallic gray Atomic mass (264) g·mol−1 Electron configuration probably [Rn] 5f14 7s2 7p1 Electrons per shell 2, 8, 18, 32, 32, 8, 3 Physical properties... The periodic table of the chemical elements A chemical element, or element, is a type of atom that is defined by its atomic number; that is, by the number of protons in its nucleus. ... General Name, Symbol, Number actinium, Ac, 89 Chemical series actinides Group, Period, Block 3, 7, f Appearance silvery Standard atomic weight (227) g·mol−1 Electron configuration [Rn] 6d1 7s2 Electrons per shell 2, 8, 18, 32, 18, 9, 2 Physical properties Phase solid Density (near r. ... General Name, Symbol, Number lawrencium, Lr, 103 Chemical series actinides Group, Period, Block n/a, 7, d Appearance unknown, probably silvery white or metallic gray Atomic mass (264) g·mol−1 Electron configuration probably [Rn] 5f14 7s2 7p1 Electrons per shell 2, 8, 18, 32, 32, 8, 3 Physical properties... The Periodic Table redirects here. ... See also: List of elements by atomic number In chemistry and physics, the atomic number (also known as the proton number) is the number of protons found in the nucleus of an atom. ...

The actinide series 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 ions. There are alternative arrangements of the periodic table that exclude actinium or lawrencium from appearing together with the other actinides. de;Metalle der Seltenen Erden Categories: Stub | Chemical element groups ... The International Union of Pure and Applied Chemistry (IUPAC) is an international non-governmental organization devoted to the advancement of chemistry. ... This article is about the electrically charged particle. ...

The actinides display less similarity in their chemical properties than the lanthanide series, 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 actinides are radioactive. The lanthanide (or lanthanoid) series comprises the 15 elements with atomic numbers 57 through 71, from lanthanum to lutetium[1]. All lanthanides are f-block elements, corresponding to the filling of the 4f electron shell, except for lutetium which is a d-block lanthanide. ... The oxidation state or oxidation number is defined as the sum of negative and positive charges in an atom, which indirectly indicates the number of electrons it has accepted or donated. ... Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting radiation in the form of particles or electromagnetic waves. ...

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 actinides were discovered in nuclear fallout, or were synthesized in particle colliders. The latter half of the series possess exceedingly short half-lives. Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ...

The actinides are typically placed below the main body of the periodic table (below the lanthanide series), in the manner of a footnote. The full-width version of the periodic table shows the position of the actinides more clearly. The lanthanide (or lanthanoid) series comprises the 15 elements with atomic numbers 57 through 71, from lanthanum to lutetium[1]. All lanthanides are f-block elements, corresponding to the filling of the 4f electron shell, except for lutetium which is a d-block lanthanide. ... This is a version of the periodic table of the elements that places all elements in the same rows. ...

An organometallic compound of an actinide is known as an organoactinide. An organometallic compound is partially characterized by the presence of one or more metal-carbon bonds, in which the carbon involved would, apart from the metal-carbon bond, be otherwise considered a part of an organic compound. ...

History of the actinide series

From the earlier known chemical properties of Actinium (89) up to Uranium (92), indicating a relation to the transition metals, it was generally assumed that the transuraniums would have similar qualities. During his Manhattan Project research in 1944, Glenn T. Seaborg 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 to have been accepted universally by the scientific community: the actinide series. In chemistry, the term transition metal (sometimes also called a transition element) has two possible meanings: It commonly refers to any element in the d-block of the periodic table, including zinc, cadmium and mercury. ... This article is about the World War II nuclear project. ... Year 1944 (MCMXLIV) was a leap year starting on Saturday (link will display full calendar) of the Gregorian calendar. ... Glenn Theodore Seaborg (April 19, 1912 – February 25, 1999) won the 1951 Nobel Prize in Chemistry for discoveries in the chemistry of the transuranium elements,[1] contributed to the discovery and isolation of ten elements, developed the actinide concept and was the first to propose the actinide series which led... Mendeleyevs portrait by Ilya Repin. ... The Periodic Table redirects here. ...

In 1945, Seaborg published his actinide concept of heavy element electronic structure, predicting that the actinides would form a transition series analogous to the rare earth series of lanthanide elements. The actinide concept in nuclear chemistry was first theorized by Glenn T. Seaborg in 1944, resulting in the correction of Mendeleyevs periodic table of the elements by placing a new actinide series below the lanthanide series. ...

In 1961, Antoni Przybylski discovered a star that contained unusually high amounts of actinides. Przybylskis Star (or HD 101065) is an unusual stellar object discovered in 1961 by Antoni Przybylski (pronounced ). Przybylskis observations indicated unusually low amounts of iron and nickel in the stars spectrum, but higher amounts of unusual elements like strontium, niobium, scandium, yttrium, cesium, neodymium, praseodymium, thorium, ytterbium...

Phase diagram of the actinide elements.

Image File history File links Size of this preview: 800 × 564 pixelsFull resolution (1163 × 820 pixel, file size: 78 KB, MIME type: image/png) Phase diagram of the Actinides. ... Image File history File links Size of this preview: 800 × 564 pixelsFull resolution (1163 × 820 pixel, file size: 78 KB, MIME type: image/png) Phase diagram of the Actinides. ...

See also

• Actinides in the environment

This article about actinides in the environment is about the sources, environmental behaviour and effects of actinides in the environment. ...

References

1. ^ IUPAC Provisional Recommendations for the Nomenclature of Inorganic Chemistry (2004) (online draft of an updated version of the "Red Book" IR 3-6)

• The Columbia Encyclopedia, Sixth Edition.
• Chemical Elements website
• Actinides on the Book Rags website
• Lawrence Berkeley Laboratory image of historic periodic table by Seaborg showing actinide series for the first time
• Lawrence Livermore National Laboratory, Uncovering the Secrets of the Actinides
• Los Alamos National Laboratory, Actinide Research Quarterly