Due to its being isotypic with uranium dioxide, these two common actinide dioxides can form solid-state solutions and the name of the mineral changes according to the ThO2 content. [131], High thorium concentrations are needed in nuclear applications. [161], Some nuclear safety agencies make recommendations about the use of thorium mantles and have raised safety concerns regarding their manufacture and disposal; the radiation dose from one mantle is not a serious problem, but that from many mantles gathered together in factories or landfills is. Thus it is a neutron poison: instead of rapidly decaying to the useful 233U, a significant amount of 233Pa converts to 234U and consumes neutrons, degrading the reactor efficiency. Over a 1‐y period, the 2 s.d. the sum of number of alpha and - 22995107 [67], In the Earth's crust, thorium is much more abundant: with an abundance of 8.1 parts per million (ppm), it is one of the most abundant of the heavy elements, almost as abundant as lead (13 ppm) and more abundant than tin (2.1 ppm). Most of the isotope data on this site has been obtained from the National Nuclear Data Center.Please visit their site for more information.. Isotopes With A … A fertile material, not itself capable of undergoing fission with low-energy neutrons, is one that decays into fissile material after neutron absorption within a reactor. Write the nuclear equation that describes the following process: uranium -235 undergoes an alpha decay to provide thorium -231. 4. 2. The chemical symbol for Platinum is Pt. Too high a temperature leads to the formation of poorly soluble thorium oxide and an excess of uranium in the filtrate, and too low a concentration of alkali leads to a very slow reaction. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope Th-231 (Thorium, atomic number Z = 90, mass number A = 231). This number of captures does not happen for 98–99% of the 232Th nuclei because the intermediate products 233U or 235U undergo fission, and fewer long-lived transuranics are produced. [9], In deep seawaters the isotope 230Th makes up to 0.04% of natural thorium. [4] Such samples slowly tarnish, becoming grey and finally black at the surface. Agreement NNX16AC86A, Is ADS down? Thorium was discovered in 1828 by the Norwegian amateur mineralogist Morten Thrane Esmark and identified by the Swedish chemist Jöns Jacob Berzelius, who named it after Thor, the Norse god of thunder. [4], At standard temperature and pressure, thorium is slowly attacked by water, but does not readily dissolve in most common acids, with the exception of hydrochloric acid, where it dissolves leaving a black insoluble residue of ThO(OH,Cl)H.[4][39] It dissolves in concentrated nitric acid containing a small quantity of catalytic fluoride or fluorosilicate ions;[4][40] if these are not present, passivation by the nitrate can occur, as with uranium and plutonium. Alpha decay (two protons. Thorium's radioactivity was widely acknowledged during the first decades of the 20th century. [148], The used fuel is difficult and dangerous to reprocess because many of the daughters of 232Th and 233U are strong gamma emitters. [46] A flame is not necessary for this effect: in 1901, it was discovered that a hot Welsbach gas mantle (using ThO2 with 1% CeO2) remained at "full glow" when exposed to a cold unignited mixture of flammable gas and air. This observation led to the identification of the half-life as one of the outcomes of the alpha particle experiments that led to the disintegration theory of radioactivity. [131], Non-radioactivity-related uses have been in decline since the 1950s[132] due to environmental concerns largely stemming from the radioactivity of thorium and its decay products. International Atomic Energy Agency (2005). 2. After thorium, there is a new downward trend in melting points from thorium to plutonium, where the number of f electrons increases from about 0.4 to about 6: this trend is due to the increasing hybridisation of the 5f and 6d orbitals and the formation of directional bonds resulting in more complex crystal structures and weakened metallic bonding. Swedish chemist, Thorium also appears in the 1864 table by British chemist. Thorium, isotope of mass 234. [103] The biological effect of radiation was discovered in 1903. No chemical toxicity has yet been observed in the tracheobronchial tract and the lungs from exposure to thorium. All of the remaining thorium isotopes have half-lives that are less than thirty days and the majority of these have half-lives that are less than ten minutes. It has been suggested as a replacement for uranium as nuclear fuel in nuclear reactors, and several thorium reactors have been built. Thorium dioxide has since been replaced in this application by rare-earth oxides, such as lanthanum, as they provide similar effects and are not radioactive.[132]. [59] It is unstable in air and decomposes in water or at 190 °C. Thorium forms the monocapped trigonal prismatic anion [Th(CH3)7]3−, heptamethylthorate, which forms the salt [Li(tmeda)]3[ThMe7] (tmeda= Me2NCH2CH2NMe2). Protactinium is a chemical element with atomic number 91 which means there are 91 protons in its nucleus.Total number of protons in the nucleus is called the atomic number of the atom and is given the symbol Z.The total electrical charge of the nucleus is therefore +Ze, where e (elementary charge) equals to 1,602 x 10-19 coulombs. Example Decay Chain of Isotope Pa-231 Thorium 232, which alone makes up nearly all natural thorium, is the most common isotope of thorium in the nature.This isotope has the longest half-life (1.4 x 10 10 years) of all isotopes with more than 83 protons. This table gives information about some radiosotopes of thorium, their masses, their half-lives, their modes of decay, their nuclear spins, and their nuclear magnetic moments. [76] Because of thorium's radioactivity, minerals containing it are often metamict (amorphous), their crystal structure having been damaged by the alpha radiation produced by thorium. Notice, Smithsonian Terms of [160] Most of the radiation dose by a normal user arises from inhaling the radium, resulting in a radiation dose of up to 0.2 millisieverts per use, about a third of the dose sustained during a mammogram. The chemical symbol for Thorium is Th.. Atomic Mass of Thorium. )[150] These impurities of 232U make 233U easy to detect and dangerous to work on, and the impracticality of their separation limits the possibilities of nuclear proliferation using 233U as the fissile material. The actual crystal structure can only be explained when the 5f states are invoked, proving that thorium, and not protactinium, acts as the first actinide metallurgically. Holmium is a relatively soft and malleable silvery-white metal. uranium-234 becomes thorium-230 ; uranium-235 becomes thorium-231 ; ... making them thorium atoms. Unlike the previous similarity between the actinides and the transition metals, the main-group similarity largely ends at thorium before being resumed in the second half of the actinide series, because of the growing contribution of the 5f orbitals to covalent bonding. 10. [156] Internal exposure to thorium leads to increased risk of liver diseases. Aluminium's is 75.2 GPa; copper's 137.8 GPa; and mild steel's is 160–169 GPa. Thorium is a weakly radioactive metallic chemical element with the symbol Th and atomic number 90. Thorium-232 and uranium-238 are the only two naturally occurring fertile materials. DTXSID90891767 [133] Thorium in mantles, though still common, has been progressively replaced with yttrium since the late 1990s. Since dissolution is very exothermic, the monazite sand cannot be added to the acid too quickly. Atomic mass of Thorium is 232.0381 u. Thorium is a weakly radioactive metallic chemical element with the symbol Th and atomic number 90. Uranium-232 (232 U) is an isotope of uranium. [120][121][122] India has projected meeting as much as 30% of its electrical demands through thorium-based nuclear power by 2050. Because the number of protons changes as a result of this nuclear reaction, the identity of the element changes. [9] Natural thorium samples can be chemically purified to extract useful daughter nuclides, such as 212Pb, which is used in nuclear medicine for cancer therapy. Magnetic separation follows, with a series of magnets of increasing strength. [124], Thorium metal was used in the radiation case of at least one nuclear weapon design deployed by the United States (the W71). [52] Thorium reacts with hydrogen to form the thorium hydrides ThH2 and Th4H15, the latter of which is superconducting below 7.5–8 K; at standard temperature and pressure, it conducts electricity like a metal. When bombarded with neutrons, thorium-232 becomes thorium-233, which eventually decays into uranium-233 through a series of beta decays. Mag-Thor alloys (also called thoriated magnesium) found use in some aerospace applications, though such uses have been phased out due to concerns over radioactivity. [28][110] Despite its radioactivity, the element has remained in use for applications where no suitable alternatives could be found. [28] Thorium oxide is being replaced in this use with other oxides, such as those of zirconium, cerium, and lanthanum. The result is a concentrate with rare-earth content of up to 90%. Absorption through the skin is possible, but is not a likely means of exposure. [169] Thorium is especially common in the Tamil Nadu coastal areas of India, where residents may be exposed to a naturally occurring radiation dose ten times higher than the worldwide average. Thus, even though the refractory elements have the same relative abundances in the Earth as in the Solar System as a whole, there is more accessible thorium than heavy platinum group metals in the crust. Image source: Thorium SVG image by Wikipedia contributor BatesIsBack . Atomic Number of Thorium. [159], Tests on the thorium uptake of workers involved in monazite processing showed thorium levels above recommended limits in their bodies, but no adverse effects on health were found at those moderately low concentrations. As a result, handling small amounts of thorium, such as those in gas mantles, is considered safe, although the use of such items may pose some risks. Thorium, isotope of mass 231. [131], Alkaline digestion is carried out in 30–45% sodium hydroxide solution at about 140 °C for about three hours.