Geographical names of chemical elements. Electronic configuration of an atom Magnetic quantum number m l

It is easy to process and has a silvery-white color. Despite its rarity and high price, thulium is used in advanced solid-state lasers and as a radioisotope in portable X-ray machines.

1. History

Tullium was discovered by the Swedish chemist Per Theodor Kleve as an impurity in the oxides of other rare earth elements (using a method proposed by Carl Gustav Mosander to search for and isolate new rare earth elements). Kleve separated all known impurities from erbium, the “earth” (oxide) element (2 3). After additional procedures, Kleve isolated two new substances: one brown, the other green. The brown was the earth, which Cleve proposed to call "holmium" and which corresponds to the element holmium, the green earth he called "Tullia" and the new element Thule in honor of Thule, the Latin name for Scandinavia.

Thulium was so rare that one of the early researchers did not have enough of it to be able to purify it enough to see the green color of its compounds, they had to rejoice, if only because the characteristic spectral lines of thulium intensified when gradually removed from the sample. Erbium was removed. The first researcher to obtain sufficiently pure thulium (thulium oxide) was Charles James, of Durham College, New Hampshire. In 1911 he reported that fractional crystallization of bromate allowed him to isolate pure material. He performed 15,000 crystallization "operations" to establish the homogeneity of his material.

High purity thulium oxide first became commercially available in the late 1950s, as a result of improvements in ion exchange separation technologies. American Potash & Chemical Corporation's Lindsay Chemical Division offered 99% and 99.9% purity grades. The price per kilogram fluctuated between US$4,600 and US$13,300 during the period from to for a 99.9% pure preparation, this was the highest price for a lanthanide after lutetium.

2. Prevalence and production

This element is never found in nature in a free state, but it is found in small quantities in minerals with other rare earth elements. Its content in the earth's crust is 0.5 mg/kg. Thulium is primarily mined from monazite (~0.007% thulium), an ore found in some sands, using ion exchange technologies. New ion exchange and organic solvent extraction technologies have made it possible to isolate thulium more efficiently and more easily, reducing the cost of its extraction. The main source of thulium today is clay deposits in southern China. In such minerals, where yttrium makes up 2/3 of the total rare earth component of the ore, there is only 0.5% thulium. Once isolated, the metal can be isolated by reducing its oxide with lanthanum or calcium in a closed reactor at high temperatures. According to another method, thulium is reduced from fluoride with metallothermic calcium:
2TmF 3 + 3Ca = 3CaF 2 + 2Tm

3. Chemical properties

Thulium reacts slowly, and at high temperatures, with atmospheric oxygen to form thulium (III) oxide:

4 Tm + 3 O 2 → 2 Tm 2 O 3

Reacts slowly with water, but the reaction accelerates when heated to form hydroxide:

2 Tm + 6 H 2 O → 2 Tm (OH) 3 + 3 H 2 2 Tm + 3 F 2 → 2 TmF 3 [white salt] 2 Tm + 3 Cl 2 → 2 TmCl 3 [yellow salt] 2 Tm + 3 Br 2 → 2 TmBr 3 [white salt] 2 Tm + 3 I 2 → 2 TmI 3 [yellow salt]

4.2. X-ray sources

Despite their high cost, portable X-ray machines use thulium as a radiation source, which was irradiated with neutrons in a nuclear reactor. These sources have been active for approximately one year as a tool in mobile medical and dental units and for identifying defects in hard-to-reach mechanical and electronic components. Such sources do not require serious radiation protection - a small coating of lead is sufficient.

5. Biological role and warnings

The biological role of thulium is not known, although it has been noted to somewhat stimulate metabolism. Soluble thulium salts are slightly toxic if introduced into the body in large quantities, but insoluble salts are non-toxic. Tullium is not absorbed by plant roots and therefore does not enter the human food chain. Vegetables typically contain only one milligram of thulium per ton of dry weight).

Literature

• Glossary of terms in chemistry / / J. Opeida, O. Shvaika. Institute of Physical-Organic Chemistry and Coal Chemistry named after L.M. Litvinenko NAS of Ukraine, Donetsk National University - Donetsk: "Weber", 2008. - 758 p. ISBN 978-966-335-206-0

Thulium - 69

Thulium (Tm) - rare earth element, atomic number 69, atomic mass 168.93, melting point 1545°C, density 9.346 g/cm3.
Thulium received its name in honor of the legendary country “Thule”, which ancient geographers considered the northernmost land, which in our time corresponds in geographical location to the Scandinavian Peninsula. Thulium was discovered in 1879 by spectroscopy. Thulium is one of the most insignificantly common lanthanides in nature; in addition, it was very difficult to isolate it from a mixture with other rare earth metals. It took several years to obtain a twenty percent thulium concentrate, and then to increase the thulium content in it to 99%. Nowadays, the chromatographic method used for the separation of rare earth metals has significantly simplified and accelerated the production of thulium oxides and, subsequently, the production of pure metal. In its pure form, thulium was obtained in 1911.
Thulium is one of the heaviest lanthanides, its density is close to that of copper and nickel.

Thulium—silver-white soft

Thulium—silver-white soft, a malleable, viscous metal, does not oxidize in air, but when heated in humid air, it oxidizes slightly. Reacts with mineral acids to produce thulium salts. Reacts with halogens and nitrogen when heated. In nature, thulium is present in minerals such as xenotime, euxenite, monazite, and loparite. The content in the earth's crust is 2.7x10-5% of the total mass. In natural and man-made types of raw materials, thulium oxide is contained extremely rarely - in eudialyte - 0.3%, and in other minerals - even less. Thirty-two artificial radioactive isotopes with different half-lives have been obtained from thulium. Only one occurs naturally, thulium-169.

RECEIPT.

After enrichment of natural minerals, the resulting concentrates from a mixture of rare earth metals are processed, as a result of which thulium is concentrated with heavy lanthanides - ytterbium and lutetium. Separation and refining are carried out by extraction or ion exchange chromatography using complexons (organic substances that form complex compounds with metal ions). Thulium metal is obtained by thermal reduction of thulium fluoride with TmF3-calcium, or thulium oxide with Tm2O3-lanthanum. Thulium is also obtained by heating thulium nitrates, sulfates and oxalates in air to 800-900°C.

APPLICATION.

Despite its low prevalence in nature and high cost, thulium, in our time, has begun to be relatively widely used in science and industry.

• Medicine. The thulium isotope, thulium-170, which has soft gamma radiation, is used to create diagnostic devices, especially for areas of the human body that are difficult to reach with a conventional X-ray machine. These radiotransmission devices with radioactive thulium are simple and easy to use in medical practice.

Flaw detection. The radioactive isotope, thulium-170, is used for flaw detection of light non-ferrous metals and their alloys, as well as thin steel plates up to 2 mm thick. Aluminum products up to 70 mm thick can be easily scanned with the thulium-170 isotope, which makes it possible to detect the smallest defects in them. In this case, a photoelectric device is used that uses thulium gamma radiation and produces a high-contrast image of the object being examined. Thulium-170 is prepared by irradiating thulium oxide with neutrons, which is placed in an aluminum ampoule and subsequently used with it.

• Laser materials. Thulium ions are used to generate infrared laser radiation. Thulium metal vapors are used to excite laser radiation with a variable frequency (wavelength). Thulium is used for the manufacture of laser materials, as well as for the manufacture of synthetic garnets.

• Magnetic media. Thulium metal is used to produce ferrogarnets to create information storage media.

• ThermoEMF materials. Thulium monotelluride has a high level of thermoEMF with high efficiency of thermal converters; however, the widespread use of thulium as thermoelements is hampered by its high cost.

• Semiconductors. Thulium telluride is used as a modifier to regulate the semiconductor properties of lead telluride.

• Nuclear power. Thulium borate is used as an additive to special enamels for protection against neutron radiation.

• Superconductors. Thulium compounds are part of high-temperature superconductor materials.

• Glass production. Thulium is a component of various oxide materials in the production of glass and ceramics for cathode ray tubes.

• Electronic configuration of an atom is a formula showing the arrangement of electrons in an atom by levels and sublevels. After studying the article, you will learn where and how electrons are located, get acquainted with quantum numbers and be able to construct the electronic configuration of an atom by its number; at the end of the article there is a table of elements.

  Why study the electronic configuration of elements?

  Atoms are like a construction set: there is a certain number of parts, they differ from each other, but two parts of the same type are absolutely the same. But this construction set is much more interesting than the plastic one and here’s why. The configuration changes depending on who is nearby. For example, oxygen next to hydrogen Maybe turn into water, when near sodium it turns into gas, and when near iron it completely turns it into rust. To answer the question of why this happens and predict the behavior of an atom next to another, it is necessary to study the electronic configuration, which will be discussed below.

  How many electrons are in an atom?

  An atom consists of a nucleus and electrons rotating around it; the nucleus consists of protons and neutrons. In the neutral state, each atom has the number of electrons equal to the number of protons in its nucleus. The number of protons is designated by the atomic number of the element, for example, sulfur has 16 protons - the 16th element of the periodic table. Gold has 79 protons - the 79th element of the periodic table. Accordingly, sulfur has 16 electrons in the neutral state, and gold has 79 electrons.

  Where to look for an electron?

  By observing the behavior of the electron, certain patterns were derived; they are described by quantum numbers, there are four in total:

  • Principal quantum number
  • Orbital quantum number
  • Magnetic quantum number
  • Spin quantum number

  Orbital

  Further, instead of the word orbit, we will use the term “orbital”; an orbital is the wave function of an electron; roughly, it is the region in which the electron spends 90% of its time.

  N - level
  L - shell
  M l - orbital number
  M s - first or second electron in the orbital
  

  Orbital quantum number l

  As a result of studying the electron cloud, they found that depending on the energy level, the cloud takes four main forms: a ball, dumbbells and two other, more complex ones. In order of increasing energy, these forms are called the s-, p-, d- and f-shell. Each of these shells can have 1 (on s), 3 (on p), 5 (on d) and 7 (on f) orbitals. The orbital quantum number is the shell in which the orbitals are located. The orbital quantum number for the s,p,d and f orbitals takes the values ​​0,1,2 or 3, respectively.

  There is one orbital on the s-shell (L=0) - two electrons
  There are three orbitals on the p-shell (L=1) - six electrons
  There are five orbitals on the d-shell (L=2) - ten electrons
  There are seven orbitals on the f-shell (L=3) - fourteen electrons
  

  Magnetic quantum number m l

  There are three orbitals on the p-shell, they are designated by numbers from -L to +L, that is, for the p-shell (L=1) there are orbitals “-1”, “0” and “1”. The magnetic quantum number is denoted by the letter m l.

  Inside the shell, it is easier for electrons to be located in different orbitals, so the first electrons fill one in each orbital, and then a pair of electrons is added to each one.

  Consider the d-shell:
  The d-shell corresponds to the value L=2, that is, five orbitals (-2,-1,0,1 and 2), the first five electrons fill the shell taking the values ​​M l =-2, M l =-1, M l =0 , M l =1,M l =2.

  Spin quantum number m s

  Spin is the direction of rotation of an electron around its axis, there are two directions, so the spin quantum number has two values: +1/2 and -1/2. One energy sublevel can only contain two electrons with opposite spins. The spin quantum number is denoted m s

  Principal quantum number n

  The main quantum number is the energy level; currently seven energy levels are known, each indicated by an Arabic numeral: 1,2,3,...7. The number of shells at each level is equal to the level number: there is one shell on the first level, two on the second, etc.

  Electron number

  
  

  So, any electron can be described by four quantum numbers, the combination of these numbers is unique for each position of the electron, take the first electron, the lowest energy level is N = 1, at the first level there is one shell, the first shell at any level has the shape of a ball (s -shell), i.e. L=0, the magnetic quantum number can take only one value, M l =0 and the spin will be equal to +1/2. If we take the fifth electron (in whatever atom it is), then the main quantum numbers for it will be: N=2, L=1, M=-1, spin 1/2.