Thulium Element

Naturally occurring Thulium has one stable isotope Tm with an atomic mass of 168.934211 (u). For thulium, 34 radioisotopes have been identified. Of these the most stable are Tm with a half-life of 1.92 years, °Tm with a half-life of 128.6 days, Tm with a half-life of 93.1 days, and Tm with a half-life of 9.25 days. All the other radioactive isotopes have half-lives that are less than 64 h, and most of them have half-lives that are less than 2 min. 

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Some nut trees accumulate mineral elements. Hickory nut is notable as an accumulator of aluminum compounds (30) the ash of its leaves contains up to 37.5% of AI2O2, compared with only 0.032% of aluminum oxide in the ash of the Fnglish walnut s autumn leaves. As an accumulator of rare-earth elements, hickory greatly exceeds all other plants their leaves show up to 2296 ppm of rare earths (scandium, yttrium, lanthanum, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium). The amounts of rare-earth elements found in parts of the hickory nut are kernels, at 5 ppm shells, at 7 ppm and shucks, at 17 ppm. The kernel of the Bra2d nut contains large amounts of barium in an insoluble form when the nut is eaten, barium dissolves in the hydrochloric acid of the stomach. 

Bivalence is similarly shown for europium, and trivalence for the elements gadolinium to thulium. 

The technical application of thulium is limited. However, the element is becoming increasingly important in special applications of lasers. 

The brittle, silvery, shiny metal was long considered the last stable element of the Periodic Table. In 2003 it was unmasked as an extremely weak alpha emitter (half-life 20 billion years). Like thulium, there is only one isotope. Bismuth alloys have low melting points (fuses, fire sprinklers). As an additive in tiny amounts, it imparts special properties on a range of metals. Applied in electronics and optoelectronics. The oxichloride (BiOCl) gives rise to pearlescent pigments (cosmetics). As bismuth is practically nontoxic, its compounds have medical applications. The basic oxide neutralizes stomach acids. A multitalented element. Crystallizes with an impressive layering effect (see right). 

Tin hold the record with 10 stable isotopes. There are 19 so-called "pure elements" of which there is only one isotope. These anisotopic elements are beryllium, fluorine, sodium, aluminum, phosphorus, scandium, manganese, cobalt, arsenic, yttrium, niobium, rhodium, iodine, cesium, praseodymium, terbium, holmium, thulium, gold, and bismuth. 

Silver-colored, ductile metal that is attacked slowly by air and water. The element exhibits interesting magnetic properties. Found in television tubes. Laser material such as YAG (yttrium-aluminum garnet) doped with holmium (as well as chromium and thulium) can be applied in medicine, especially in sensitive eye operations. 

The silver gray metal can be cut with a knife, although it only melts at 1545 °C (for comparison, iron 1538 °C). It is the rarest of the "rare earths", but is nevertheless more abundant than iodine, mercury, and silver. Thulium has few applications, especially because it is relatively expensive. The element occurs naturally as a single isotope, namely 169Tm (compare bismuth). The artificial, radioactive 170Tm is a transportable source of X-rays for testing materials. Occasionally used in laser optics and microwave technology. 

Phosphorus is an unusual element, because it has only one single isotope, phosphorus-31, and that this isotope is NMR-active with a spin of xh. The only other elements for which this is the case are fluorine, yttrium, rhodium and thulium. 

A salt of thulium can be made radioactive, and is used in medical X rays. Gadolinium is one of the few magnetic elements. 

These include the following 14 elements cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmi-um, erbium, thulium, ytterbium, and lutetium. 

ISOTOPES There are a total of 46 isotopes of thulium. One of these, Tm-169 is the only stable isotope of thulium and accounts for the total atomic mass of the element. All the other isotopes are artificially produced and radioactive and have half-lives ranging from a few microseconds to two years. 

Thulium is near the end of the lanthanide series, where the metals tend to be heavier than the ones located near the beginning of the series. It is so scarce that it requires the processing of about 500 tons of earth to extract four kilograms of thulium. The only element that is scarcer is promethium, which is not found naturally on Earth. 

Similar to other rare-earths, thulium has a single oxidation state of +3. A general formula for the positive ion of thulium and the elements found in group 7 (fluorides) with a negative ion is expressed as follows ... 

The dust and powder of thulium are explosive and toxic if inhaled or ingested. As with all radioactive elements, thuhum can cause radiation poisoning. 

Before their experiment that produced mendelevium, the team had speculated that this element number 101 must be somewhat similar to the element thulium ( Tm) located just above it in the lanthanide series. Because they did not have a name for this new element, they referred to it as eka-thuhum, with an atomic number of 101. It was formally named mendelevium in 1955 only after they were able to produce a few atoms of einsteinium by the nuclear process as follows gjEs-253 + —> Md-256 + n-1 (a neutron with a mass of... 

Soret and Delafontaine identified holmium in 1878 by examination of its spectrum. The following year, Cleve separated its oxide from Marignac s erbia, a mixture of erbium, holmium and thulium oxides. He named this element Holmium, after his native town Holmia (Stockholm). The metal was produced in 1934 by Klemm and Bommer. 

Holmium is obtained from monazite, bastnasite and other rare-earth minerals as a by-product during recovery of dysprosium, thulium and other rare-earth metals. The recovery steps in production of all lanthanide elements are very similar. These involve breaking up ores by treatment with hot concentrated sulfuric acid or by caustic fusion separation of rare-earths by ion-exchange processes conversion to halide salts and reduction of the hahde(s) to metal (See Dysprosium, Gadolinium and Erbium). 

Thulium was discovered in 1879 by Cleve and named after Thule, the earliest name for Scandinavia. Its oxide thulia was isolated by James in 1911. Thulium is one of the least abundant lanthanide elements and is found in very small amounts with other rare earths. It occurs in the yttrium-rich minerals xenotime, euxenite, samarskite, gadolinite, loparite, fergusonite, and yttroparisite. Also, it occurs in trace quantities in minerals monazite and... 

Of the remaining elements such as holmium, erbium, thulium ytterbium and lutetium it is unfortunately true that their relatively low abundance coupled with high cost has tended to preclude their use in applications outside of the laboratory. 

After the brilliant researches of Bunsen and Kirchhoff had paved the way, other new elements were soon revealed by the spectroscope. Among these may be mentioned thallium, indium, gallium, helium, ytterbium, holmium, thulium, samarium, neodymium, praseodymium, and lutetium. 

Moseley s work not only shed much fight on the periodic system and the relationships between known elements and the radioactive isotopes, but was also a great stimulus in the search for the few elements remaining undiscovered (11). One of the first chemists to utilize the new method was Professor Georges Urbain of Paris, who took his rare earth preparations to Oxford for examination. Moseley showed him the characteristic fines of erbium, thulium, ytterbium, and lutetium, and confirmed in a few days the conclusions which Professor Urbain had made after twenty years... 

In 1955 the next step was announced. Very intense helium ion bombardment of tiny targets of E253 produced a few spontaneously fissionable atoms which eluted from ion-exchange resins in the eka-thulium position. This was evidence that element 101 had been found. Only seventeen atoms of this element were produced. It showed a half-life of between one-half and several hours. The name mendelevium (symbol... 

Even more striking in the old tooth is the abundance of rare earths (dysprosium, holmium, erbium, thulium, ytterbium, and lutetium) and the elements tantalum, tungsten, gold, thorium, and uranium. Rare earth minerals are found in Scandinavia (in fact, many rare earth elements were discovered there), but what were they used for Did people prepare food with them Did they somehow get into the food chain ... 

Ionic radius Tm3+ 0.880 A. Metallic radius 1.746 A. First ionization potential 6.18 V second 12.05 V. Odier physical properties of thulium are given under Rare-Earth Elements and Metals. 

Important scientific and industrial applications for thulium and its compounds remain to be developed. In particular, the photoelectric, semiconductor, and thermoelectric properties of the element and compounds, particularly behavior in the near-infrared region of the spectrum, are being studied. Thulium has been used in phosphors, ferrite bubble devices, and catalysis. Irradiated thulium (169Tm) is used in a portable x-ray unit. 

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