Isotopes. Presentation "isotopes and their applications" Isotopes and their applications presentation
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Isotopes These are varieties of a given chemical element, differing in the mass of atomic nuclei. These are varieties of atoms (and nuclei) of the same chemical element with different numbers of neutrons in the nucleus.
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History of the discovery of isotopes The first evidence that substances having the same chemical behavior can have different physical properties was obtained from the study of radioactive transformations of atoms of heavy elements. In 1906-07, it turned out that the product of radioactive decay of uranium - ionium and the product of radioactive decay of thorium - radiothorium, have the same chemical properties as thorium, but differ from it in atomic mass and radioactive decay characteristics. It was later discovered that all three products had identical optical and x-ray spectra.
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Substances that are identical in chemical properties, but different in the mass of atoms and some physical properties, at the suggestion of the English scientist F. Soddy, began to be called isotopes.
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Isotopes of Hydrogen Hydrogen occurs in the form of three isotopes, which have individual names: 1H - protium (H), 2H - deuterium (D), 3H - tritium (T; radioactive). Protium and deuterium are stable isotopes with mass numbers 1 and 2. Their content in nature is 99.98% and 0.01%, respectively. This ratio may vary slightly depending on the source and method of producing hydrogen.
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Isotopes of hydrogen 3 H - tritium (T) radioactive). The hydrogen isotope 3H (tritium) is unstable. Its half-life is 12.32 years. Tritium occurs naturally in very small quantities.
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isotopes are located in the same place (in the same cell) of the periodic table. 16 17 18 O, O, O - three stable isotopes of oxygen All isotopes of one element have the same nuclear charge (oxygen has 8), differing only in the number of neutrons. Usually an isotope is indicated by the symbol of the chemical element to which it belongs, with the addition of an upper left index indicating the mass number
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Radioactive isotopes are isotopes whose nuclei are unstable and undergo radioactive decay. Most known isotopes are radioactive (only about 300 of the more than 3,000 nuclides known to science are stable). Any chemical element has at least several radioactive isotopes, while at the same time, not all elements have at least one stable isotope; Thus, all known isotopes of all elements that come after lead in the periodic table are radioactive.
“Obtaining radioactive isotopes” - Medicine. Application of radioactive isotopes. Industry. This method is used to determine the age of Egyptian mummies and the remains of prehistoric fires. Radioactive isotopes are sources of radiation. The “labeled atoms” method has become one of the most effective. Radioactive isotopes in archeology. Elements that do not exist in nature.
“Hydrogen in the periodic table” - Hydrogen atom. Position of hydrogen in the periodic table. 2) Reduction: Redox reaction between hydrogen and fluorine. Explosive gas. 1)Oxidation:
“Silicon isotopes” - Zone-purified silicon. Distribution of the silicon-29 isotope along the length of the seed. Separation of silicon isotopes. Isotope dilution during single crystal growth from a quartz crucible. Monocrystal of natural silicon. Preparation of a substrate rod from monoisotopic silicon. - Experiment. Impurity composition of single-crystal monoisotopic silicon.
“Hydrogen atom” - Its content in the earth’s crust reaches 0.15% of its mass. Its properties are more similar to halogens than to alkali metals. Electronic configuration 1s1. Hydrogen ranks first in the periodic table (Z = 1). Chemical properties. At a temperature of -252.8°C and atmospheric pressure it turns into a liquid state.
“Radioactive elements” - Hydrothermal treatment of TiO2·nH2O gel (T = 110 – 250 ? C; t = 20 h). Since April 12, 2008 Website www.nanometer.ru Emblem competition. + 2H+. H2O. Production 105/t Inventories 5· 108/t. OH. Ti. Graphite, anode. Tin bridges. Natural forms, obtaining. C or ti crucible (cathode). Ti, Zr, Hf, Rf (Th). O. O H. Chemistry of elements of group IV DPVPS.
“Application of isotopes” - About radiation. Atomic energy and the use of artificial radioactive isotopes. Application of natural radioactive elements. The use of isotopes in diagnostics Therapeutic use of isotopes. The use of artificial radioactive elements. Therapeutic uses of radium Determining the age of the Earth. Application of isotopes in the study of plant nutrition.
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ISOTOPES are varieties of the same chemical element that are similar in their physicochemical properties, but have different atomic masses. The name “isotopes” was proposed in 1912 by the English radiochemist Frederick Soddy, who formed it from two Greek words: isos - identical and topos - place. Isotopes occupy the same place in the cell of Mendeleev's periodic table of elements.
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An atom of any chemical element consists of a positively charged nucleus and a cloud of negatively charged electrons surrounding it. The position of a chemical element in the periodic table of Mendeleev (its serial number) is determined by the charge of the nucleus of its atoms. According to the figurative expression of F. Soddy, the atoms of isotopes are the same “outside”, but different “inside”.
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In 1932, the neutron was discovered - a particle that has no charge, with a mass close to the mass of the nucleus of a hydrogen atom - a proton, and a proton-neutron model of the nucleus was created. As a result, science has established the final modern definition of the concept of isotopes: isotopes are substances whose atomic nuclei consist of the same number of protons and differ only in the number of neutrons in the nucleus. Each isotope is usually denoted by a set of symbols, where X is the symbol of the chemical element, Z is the charge of the atomic nucleus (the number of protons), A is the mass number of the isotope (the total number of protons and neutrons in the nucleus, A = Z + N). Because the nuclear charge appears to be uniquely associated with the symbol of the chemical element, the symbol AX is often used for abbreviation. Of all the isotopes known to us, only hydrogen isotopes have their own names. Thus, the isotopes 2H and 3H are called deuterium and tritium.
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In nature, there are both stable isotopes and unstable ones - radioactive ones, the nuclei of atoms of which are subject to spontaneous transformation into other nuclei with the emission of various particles. About 270 stable isotopes are now known. The number of unstable isotopes exceeds 2000, the vast majority of them are obtained artificially as a result of various nuclear reactions. The number of radioactive isotopes of many elements is very large and can exceed two dozen. The number of stable isotopes is significantly smaller; some chemical elements consist of only one stable isotope (beryllium, fluorine, sodium, aluminum, phosphorus, manganese, gold, etc.). The largest number of stable isotopes - 10 - was found in tin, for example in iron there are 4, and in mercury - 7.
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Discovery of isotopes In 1808, the English scientist naturalist John Dalton first introduced the definition of a chemical element as a substance consisting of atoms of the same type. In 1869, the chemist D.I. Mendeleev discovered the periodic law of chemical elements. One of the difficulties in substantiating the concept of an element as a substance occupying a certain place in a cell of the periodic table was the experimentally observed non-integer atomic weights of elements. In 1866, the English physicist and chemist Sir William Crookes put forward the hypothesis that each natural chemical element is a certain mixture of substances that are identical in their properties, but have different atomic masses, but at that time such an assumption did not yet have experimental confirmation.
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An important step towards the discovery of isotopes was the discovery of the phenomenon of radioactivity and the hypothesis of radioactive decay formulated by Ernst Rutherford and Frederick Soddy: radioactivity is nothing more than the decay of an atom into a charged particle and an atom of another element, different in its chemical properties from the original one. As a result, the idea of radioactive series or radioactive families arose, at the beginning of which there is the first parent element, which is radioactive, and at the end - the last stable element. Analysis of the chains of transformations showed that during their course, the same radioactive elements, differing only in atomic masses, can appear in one cell of the periodic table. In fact, this meant the introduction of the concept of isotopes.
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Independent confirmation of the existence of stable isotopes was then obtained in experiments by Thomson and Aston in 1912–1920 with beams of positively charged particles emerging from a discharge tube. In 1919, Aston constructed an instrument called a mass spectrograph. The ion source still used a discharge tube, but Aston found a way in which successive deflection of a beam of particles in electric and magnetic fields led to the focusing of particles with the same charge-to-mass ratio (regardless of their speed) at the same point on the screen. As a result of the subsequent use and improvement of mass spectrometers through the efforts of many researchers, by 1935 an almost complete table of the isotopic compositions of chemical elements was compiled.
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Isotope technologies are widely used in medicine. Thus, in the USA, according to statistics, more than 36 thousand medical procedures are performed per day and about 100 million laboratory tests using isotopes. The most common procedures involve computed tomography. The carbon isotope C13, enriched to 99% (natural content about 1%), is actively used in the so-called “diagnostic breathing monitoring”. The essence of the test is very simple. The enriched isotope is introduced into the patient's food and, after participating in the metabolic process in various organs of the body, is released in the form of carbon dioxide CO2 exhaled by the patient, which is collected and analyzed using a spectrometer. The differences in the rates of processes associated with the release of different amounts of carbon dioxide, labeled with the C13 isotope, make it possible to judge the condition of the patient’s various organs. In the US, the number of patients who will undergo this test is estimated at 5 million per year. Now laser separation methods are used to produce highly enriched C13 isotope on an industrial scale.
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- ISOTOPES are varieties of the same chemical element that are similar in their physicochemical properties, but have different atomic masses. The name “isotopes” was proposed in 1912 by the English radiochemist Frederick Soddy, who formed it from two Greek words: isos - identical and topos - place. Isotopes occupy the same place in the cell of Mendeleev's periodic table of elements.
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- An atom of any chemical element consists of a positively charged nucleus and a cloud of negatively charged electrons surrounding it. The position of a chemical element in the periodic table of Mendeleev (its serial number) is determined by the charge of the nucleus of its atoms. According to the figurative expression of F. Soddy, the atoms of isotopes are the same “outside”, but different “inside”.
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- In 1932, a neutron was discovered - a particle that has no charge, with a mass close to the mass of the nucleus of a hydrogen atom - a proton, and a proton-neutron model of the nucleus was created. As a result, science established the final modern definition of the concept of isotopes: isotopes are substances whose atomic nuclei consist of the same number of protons and differ only in the number of neutrons in the nucleus. Each isotope is usually denoted by a set of symbols, where X is the symbol of the chemical element, Z is the charge of the atomic nucleus (the number of protons), A is the mass number of the isotope (the total number of protons and neutrons in the nucleus, A = Z + N). Because the nuclear charge appears to be uniquely associated with the symbol of the chemical element, the symbol AX is often used for abbreviation.
- Of all the isotopes known to us, only hydrogen isotopes have their own names. Thus, the isotopes 2H and 3H are called deuterium and tritium.
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- In nature, there are both stable isotopes and unstable ones - radioactive ones, the nuclei of atoms of which are subject to spontaneous transformation into other nuclei with the emission of various particles. About 270 stable isotopes are now known. The number of unstable isotopes exceeds 2000, the vast majority of them are obtained artificially as a result of various nuclear reactions. The number of radioactive isotopes of many elements is very large and can exceed two dozen. The number of stable isotopes is significantly smaller; some chemical elements consist of only one stable isotope (beryllium, fluorine, sodium, aluminum, phosphorus, manganese, gold, etc.). The largest number of stable isotopes - 10 - was found in tin, for example in iron there are 4, and in mercury - 7.
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Discovery of isotopes
- In 1808, the English scientist naturalist John Dalton first introduced the definition of a chemical element as a substance consisting of atoms of the same type. In 1869, the chemist D.I. Mendeleev discovered the periodic law of chemical elements. One of the difficulties in substantiating the concept of an element as a substance occupying a certain place in a cell of the periodic table was the experimentally observed non-integer atomic weights of elements. In 1866, the English physicist and chemist Sir William Crookes put forward the hypothesis that each natural chemical element is a certain mixture of substances that are identical in their properties, but have different atomic masses, but at that time such an assumption did not yet have experimental confirmation.
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- An important step towards the discovery of isotopes was the discovery of the phenomenon of radioactivity and the hypothesis of radioactive decay formulated by Ernst Rutherford and Frederick Soddy: radioactivity is nothing more than the decay of an atom into a charged particle and an atom of another element, different in its chemical properties from the original one. As a result, the idea of radioactive series or radioactive families arose, at the beginning of which there is the first parent element, which is radioactive, and at the end - the last stable element. Analysis of the chains of transformations showed that during their course, the same radioactive elements, differing only in atomic masses, can appear in one cell of the periodic table. In fact, this meant the introduction of the concept of isotopes.
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- Independent confirmation of the existence of stable isotopes was then obtained in experiments by Thomson and Aston in 1912–1920 with beams of positively charged particles emerging from a discharge tube.
- In 1919, Aston designed an instrument called a mass spectrograph. The ion source still used a discharge tube, but Aston found a way in which successive deflection of a beam of particles in electric and magnetic fields led to the focusing of particles with the same charge-to-mass ratio ( regardless of their speed) at the same point on the screen. As a result of the subsequent use and improvement of mass spectrometers through the efforts of many researchers, by 1935 an almost complete table of the isotopic compositions of chemical elements was compiled.
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Application of isotopes
- Various isotopes of chemical elements are widely used in scientific research, in various fields of industry and agriculture, in nuclear energy, modern biology and medicine, in environmental studies and other fields. Scientific research requires small quantities of rare isotopes of various elements, measured in grams and even milligrams per year. At the same time, for a number of isotopes widely used in nuclear energy, medicine and other industries, the need for their production can amount to many kilograms and even tons. In scientific research, stable and radioactive isotopes are widely used as isotopic tracers in the study of a wide variety of processes occurring in nature. In agriculture, isotopes are used, for example, to study the processes of photosynthesis, the digestibility of fertilizers and to determine the efficiency of plants using nitrogen, phosphorus, microelements and other substances.
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- Isotope technologies are widely used in medicine. Thus, in the USA, according to statistics, more than 36 thousand medical procedures are performed per day and about 100 million laboratory tests using isotopes. The most common procedures involve computed tomography. The carbon isotope C13, enriched to 99% (natural content about 1%), is actively used in the so-called “diagnostic breathing monitoring”. The essence of the test is very simple. The enriched isotope is introduced into the patient's food and, after participating in the metabolic process in various organs of the body, is released in the form of carbon dioxide CO2 exhaled by the patient, which is collected and analyzed using a spectrometer. The differences in the rates of processes associated with the release of different amounts of carbon dioxide, labeled with the C13 isotope, make it possible to judge the condition of the patient’s various organs. In the US, the number of patients who will undergo this test is estimated at 5 million per year. Now laser separation methods are used to produce highly enriched C13 isotope on an industrial scale.
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KOU VO "TSLPDO" ISOTOPES Presentation for the lesson Chemistry 8th grade Prepared by teacher Olkhovikova G.P. Technical consultant Olkhovikova S.M. 2016
Basic concepts Isotopes Relative atomic mass Ordinal number Nucleus Proton Neutron Electron Arithmetic mean
Isotopes are atoms of the same chemical element with identical nuclear charges, but different relative atomic masses due to different numbers of neutrons in the nucleus. Relative atomic mass shows how many times the mass of an atom of a chemical element is greater than 1/12 the mass of a carbon atom. There is no need to memorize the values of the relative atomic masses of chemical elements; they are given in any textbook or reference book on chemistry, as well as in the periodic table of D.I. Mendeleev. The serial number of the element in the table D.I. Mendeleev corresponds to the number of protons in the nucleus of an atom. An atom is the smallest particle of matter, consisting of a nucleus and electrons.
The nucleus is the central part of the atom, consisting of protons and neutrons, in which the bulk of the atom's mass is concentrated. A proton is an elementary particle with a charge of +1 and a relative mass equal to one. A neutron is a particle entering the nucleus of an atom, devoid of an electric charge, and having a relative mass equal to unity. An electron is the smallest particle of a substance with a negative electric charge e=1.6·10-19 coulombs, taken as an elementary electric charge (-1). The arithmetic mean is the sum of all recorded values, divided by their number.
Neutron + - proton 16 - - electron Oxygen consists of three isotopes – , and. Atoms have an equal number of protons, but differ in the content of neutrons. Isotope Protons Number Neutrons Number 8 8 8 9 8 10 Isotope Protons Number Neutrons Number 8 8 8 9 8 10 - - - - - - - - + + + + + + + + 1 8 - - - - - - - - + + + + + + + +
99.76% 0 . 203% 0. 037% The concentration of oxygen isotopes in water molecules is different. The isotopic composition of substances using water as an example (H 2 O) H 2 O
Natural water can be considered as a mixture of a low-boiling component H 2 16 O with a boiling point (at normal pressure) of 100 0 C and a high-boiling component H 2 18 O with a boiling point of 100.15 0 C. O-16 (t 0 C = 100.0 0 C) O-18 (t 0 C = 100.15 0 C) H 2 O H 2 16 O H 2 16 O H 2 16 O H 2 18 O H 2 18 O H 2 18 O
The importance of isotopes for practical human activities Isotopes play a significant role in many areas of human activity, namely: Medicine (diagnosis and treatment of cancer) Basic science (production and study of neutrinos (“dark matter”) Electronics (semiconductors, equipment) Environmental research ( soil, fertilizers)
Quiz tests 1. What is an atom? What is its structure? 2. How to determine the number of protons in an atom? Number of electrons? 3. How to determine the number of neutrons in an atom? 4. Explain the meaning of the concept of “isotopes” using the example of the chemical element oxygen.
Test questions 4. How does isotopic composition affect the physical properties of substances? 5. In what areas of practical activity are isotopes used? Homework. Prepare a message in accordance with the fifth question.
Literature 1.Isotopes: properties, preparation, application, Volume 1 - M.: FIZMATLIT, 2005. - 600 p. 2.Isotopes: properties, preparation, application, Volume 2 - Baranov V.Yu. FIZMATLIT, Moscow, 2005, 728 pp., UDC: 546.02+621.039.8, ISBN: 5-9221-0523-X 3. Isotopes, their properties and application http:// www.muctr.ru/univsubs/infacol /ifh/faculties/f4/isotops.php 4. Radzig A.A., Smirnoe B.M. Parameters of atoms and atomic ions. Directory. - M.: Energoatomizdat, 1986. - 344 p.
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