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Uranium is now known to comprise 2.1 ppm of the Earth’s crust, which makes it about as abundant as arsenic or europium. Klaproth showed in 1789 that pitchblende contained a new element and named it uranium after the then newly discovered planet Uranus. Uranium was the first actinide element to be discovered. It was not until 1971 that the existence of primordial 244 Pu in nature in trace amounts was shown by D. In addition to thorium and uranium, protactinium and actinium have been found to exist in uranium and thorium ores due to the 238 U and 235 U decay series: −β − 234 −β − 234 −α 234 238 92 U −→ 90 Th −→ 91 Pa −→ 92 U, Only three actinide elements and actinium were known as late as 1940. Naturally Occurring Actinides All of the isotopes of the actinide elements are radioactive, and only four of the primordial isotopes, 232 Th, 235 U, 238 U, and 244 Pu, have a sufficient long half-life for there to be any of these isotopes left in nature. DISCOVERY, OCCURRENCE, AND SYNTHESIS OF THE ACTINIDES A. However, owing to wide current use, “actinide” is still allowed.

According to the International Union of Pure and Applied Chemistry (IUPAC), the name actinoid is preferable to actinide because the ending “-ide” normally indicates a negative ion. P1: FYK Revised Pages Encyclopedia of Physical Science and TechnologyĪtomic number 89) is usually included in discussions about the actinides. Although not formally an actinide element, actinium (Ac

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The actinides constitute a unique series of elements which are formed by the progressive filling of the 5 f electron shell. THE ACTINIDE ELEMENTS (actinoids) comprise the 14 elements with atomic numbers 90–103, which follow actinium in the periodic table: thorium (Th), protactinium (Pa), uranium (U), neptunium (Np), plutonium (Pu), americium (Am), curium (Cm), berkelium (Bk), californium (Cf), einsteinium (Es), fermium (Fm), mendelevium (Md), nobelium (No), and lawrencium (Lr). At present, bohrium (Bh), element 107, is the heaviest element which has been characterized chemically chemical studies of element 108, hassium (Hs), and element 112 are in preparation. The heaviest elements, synthesized until now, are the elements 114, 116, and 118. Transactinide elements Artificial elements beyond the actinide elements, beginning with rutherfordium (Rf), element 104. Speciation Characterization of physical and chemical states of (actinide) species in a given (chemical) environment. Radioactivity The property of certain nuclides of showing radioactive decay in which particles or γ radiation are emitted or the nucleus undergoes spontaneous fission. Primordial radionuclides Nuclides which were produced during element evolution and which have partly survived since then due to their long halflives. Nuclide A species of atom characterized by its mass number, atomic number, and nuclear energy state. Nuclear fission The division of a nucleus into two or more parts, usually accompanied by the emission of neutrons and γ radiation. Lanthanides Fourteen elements with atomic numbers 58 (cerium) to 71 (lutetium) that are a result of filling the 4 f orbitals with electrons.

Decay chain A series of nuclides in which each member transforms into the next through nuclear decay until a stable nuclide has been formed. GLOSSARY 2+ Actinyl ion Dioxo actinide cations MO+ 2 and MO2. Radioactivity and Nuclear Reactions of Actinides III. Discovery, Occurrence, and Synthesis of the Actinides II. Pages 513-550 Pages 303-317 Pages 463-492 Pages 449-461 Pages 671-695 Pages 1-22Īctinide Elements Siegfried Hubener ¨ Forschungszentrum Rossendorf Henze (Chemistry) Rare Earth Elements Zhiping Zheng and John E. Noble Metals Cihonski (Chemistry) Noble-Gas Chemistry

Metal Particles and Cluster Compounds Klabunde Nano sized Inorganic Leroy Cronin, Achim Müller and Dieter Fenske Clusters Hubert Schmidbaur and John L. Main Group Elements Mesoporous Materials, Synthesis Metal Cluster Chemistry Inclusion (Clathrate) Compounds Inorganic Exotic Molecules Table of Contents (Subject Area: Inorganic Chemistry) Articleīrian T. Encyclopedia of Physical Science and Technology

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