Presentation "crystalline and amorphous bodies". Amorphous bodies and crystal lattices Presentation on the topic of crystalline and amorphous bodies
Crystalline and amorphous bodies Completed by: Elena Anatolyevna Gotmanova, physics teacher at Municipal Educational Institution “Secondary School No. 15”, r.p. Pervomaisky Shchekinsky district 01/14/2008 ABSTRACT The presentation can be used partially in physics lessons in the 8th grade and completely in the 10th grade; on extracurricular activities(physics weeks, seminars, lessons with interdisciplinary connections) Done in Microsoft PowerPoint Volume of work - , number of slides - 16 Goals and objectives To familiarize students with the structure and properties of solids; Show the role of solid state physics in the creation of materials with predetermined properties; Show the formula of crystals, the symmetry of spatial crystal lattices; Show practical significance solids Methodological recommendations for the teacher This presentation can be used in grade 10 with both two and three hours allocated to the topic “Solids”; To implement differentiated learning, solving high-quality problems can be offered both to the whole class and partially to students with different levels of knowledge; In grade 8, presentation materials related to the study of crystalline solids can be used. Methodological recommendations for students This presentation supports interest in the study of physics; By using this presentation, you expand your horizons, develop abstract thinking; This presentation allows you to consolidate self-education skills. Features of the internal molecular structure of solids. Their properties Crystal is a stable, ordered formation of particles in the solid state. Crystals are distinguished by spatial periodicity of all properties. The main properties of crystals: retains shape and volume in the absence of external influences, has strength, a certain melting point and anisotropy (the difference in the physical properties of the crystal from the chosen direction). Observation of the crystal structure of some substances salt quartz mica diamond Single crystals and polycrystals Metals have a crystalline structure. Typically, a metal consists of a huge number of small crystals fused together. A solid consisting of a large number of small crystals is called polycrystalline. Single crystals are called single crystals. Most crystalline solids are polycrystals, as they consist of many intergrown crystals. Single crystals - single crystals have a regular geometric shape and their properties vary depending on the direction. Historical background 1867 Russian engineer A.V. Gadolin was the first to prove that crystals can have 32 types of symmetry. The famous Russian crystallographer E.S. Fedorov proved that there can only be 230 ways to build a crystal. Scientists have found out correct form crystal is due to the close, ordered arrangement of particles in the crystal Demonstration of various models of crystal lattices diamond graphite salt Note the same distance between salt particles in certain directions Models of crystal lattices of graphite and diamond are an example of polymorphism, when the same substance can have Various types packaging Demonstration of evidence of the properties of amorphous bodies 1. Amorphous bodies do not have a specific melting point paraffin glass 2. Amorphous bodies are isotropic, for example: paraffin plasticine The strength of these bodies does not depend on the choice of test direction Demonstration of evidence of the properties of amorphous bodies 3. With short-term exposure they exhibit elastic properties. For example: rubber balloon 4. With prolonged external influence, amorphous bodies flow. For example: paraffin in a candle. 5. Over time, they become cloudy (ex: glass) and devitrify (ex: candy candy), which is associated with the appearance of small crystals, the optical properties of which differ from the properties of amorphous bodies. Solution of qualitative problems A ball made of a single crystal when heated can change not only its volume, but also its shape. Why? A glass cube and a quartz monocrystal cube dipped in hot water. Do the cubes retain their shape? Why don’t spherical crystals exist in nature? Why does snow squeak underfoot in cold weather? Why are there no melting points for glass in the tables of melting points of various substances? Results Students became familiar with the structure and properties of solids; We became familiar with the role of solid state physics in the creation of materials with predetermined properties; Students saw the formula of crystals, the symmetry of spatial crystal lattices; We looked at the practical significance of solids. References 1. 2. 3. O.F. Kabardin Physics. Reference materials. Kabardin O.F. - M. “Enlightenment”, 1988, 367 p. G.Ya. Myakishev, B.B. Bukhovtsev, N.N. Sotsky – Physics. Textbook for 10th grade of general education institutions. Myakishev G.Ya., Bukhovtsev B.B., Sotsky N.N. - Literature, “Enlightenment”, 2007, 366 p. I.G. Vlasova, A.A. Vitebskaya Solving problems in physics. School Student's Handbook. – Vlasova I.G., Vitebskaya A.A., Philological Society “Slovo”, AST, Klyuch-S, Center for the Humanities at the Faculty of Journalism of Moscow State University. M.V. Lomonosov, -M., 1997, 638 p. Answers to qualitative problems A monocrystal is a single crystal in which physical properties depend on the direction inside the crystal, that is, it has anisotropy. Therefore, a ball made of a single crystal, when heated, can expand in different directions unequally, therefore, it can change not only its volume, but also its shape. Glass is an amorphous solid and is isotropic. Single crystals are anisotropic. Consequently, due to the anisotropy of thermal expansion (thermal expansion is not the same in different directions), the quartz cube will take the shape of a parallelepiped. A glass cube will not change its shape. All single crystals are anisotropic, that is, physical properties depend on the direction within the crystals. Consequently, crystal growth is not the same in different directions, and therefore a spherical crystal cannot be grown. Snow consists of a huge number of crystalline snowflakes. In cold weather, the snow creaks under your feet because hundreds of thousands of crystals break on the floor under the force of your feet. This is due to the fact that glass is an amorphous substance that does not have a specific melting point.
Crystalline
and amorphous
Prepared by: teacher of mathematics and physics of OGBOU SPO "Tulun Agrarian College" Guznyakov Alexander Vasilievich
Lesson objectives:
educational-
- form the concepts: “crystalline body”, “crystal lattice”, “monocrystal”, “polycrystal”, “amorphous body”;
- identify the basic properties of crystalline and amorphous bodies;
- develop the ability to highlight the main thing;
- develop the ability to systematize material;
- develop cognitive interest in the subject using various forms of work;
- cultivate a scientific worldview.
developing-
educational -
The barely transparent ice, dimming over the lake, covered the motionless streams with crystal.
A.S. Pushkin.
And the crazy chill of emerald, And the warmth of golden topaz, And the wisdom of simple calcite - Only they will never deceive. In them, in the silent fragments of the universe, Sparks of eternal harmonies sparkle. The arrogant image of everyday life fades and melts in these sparks. They give peace and protection, They give the fire of inspiration, entwined in a single chain, with our frailty - links in eternity.
Victor Sletov
emerald crystals
Practical work
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Indications dry thermometer, °С |
Reading difference dry and wet thermometers, °C |
Wet thermometer readings, °C |
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Define
humidity
Entrance test
1. Name the three states of matter of matter.
- gaseous, liquid, solid.
2. Complete the sentence.
“The state of aggregation of a substance is determined by the location, nature of movement and interaction...”
- molecules.
Entrance test
3. Find a match between state of aggregation substances and the distance between molecules.
- 1b; 2a; 3c.
4. Name the properties of solids.
- retain volume and shape.
1) gaseous;
2) hard;
3) liquid.
a) located in an orderly manner, close to each other;
b) the distance is many times greater than the size of the molecules;
c) located randomly next to each other.
Entrance test
5. Fill in the missing words.
“The transition of a substance from a liquid to a solid state is called ... or ... "
- hardening, crystallization.
Most of the solids around us are substances in a crystalline state. These include building and structural materials: various grades of steel, all kinds of metal alloys, minerals, etc. A special field of physics is solid state physics - deals with the study of the structure and properties of solids. This area of physics is leading in all physical research. It forms the foundation of modern technology.
Solid state physics
Properties of Solids
Doesn't change
Doesn't change
What is the reason?
Properties of crystalline solids
- Melting point is constant
- Have a crystal lattice
- Each substance has its own melting point.
- Anisotropic (mechanical strength, optical, electrical, thermal properties)
Types of crystals
Amorphous substances
(different Greek ἀ “non-” and μορφή “type, form”) do not have a crystalline structure and, unlike crystals, do not split to form crystalline faces; as a rule, they are isotropic, that is, they do not exhibit different properties in different directions, do not have a certain melting point.
Properties of amorphous bodies
- Do not have a constant melting point
- They do not have a crystalline structure
- Isotropic
- Have fluidity
- Capable of transitioning into crystalline and liquid states.
- Have only “short-range order” in the arrangement of particles
Minerals
Variety of crystals
Amorphous bodies
Look to the root
Types of crystals
Cubic system
Tetragonal
Hexagonal
Rhombohedral
Rhombic
Monoclinic
Triclinic
Liquid crystals
substances that simultaneously have
properties like liquids (fluidity),
and crystals (anisotropy).
Application of liquid crystals
Pressure meters and ultrasound detectors have been created based on liquid crystals. But the most promising area of application of liquid crystalline substances is information technology. Only a few years have passed from the first indicators, familiar to everyone from digital watches, to color televisions with LCD screens the size of a postcard. Such televisions provide an image that is very High Quality, consuming an insignificant amount of energy from a small-sized battery or battery.
Diamond cutting
The diamond is recognized as the most beautiful and frequently used form of brilliant cut, created for the optimal combination of brilliance and the “play” of light, revealing the jewelry properties of the diamond.
Diamond "Shah"
Diamond "Orlov"
Problem solving
1. A ball machined from a single crystal, when heated, can change not only its volume, but also its shape. Why?
Answer :
Due to anisotropy, crystals expand unevenly when heated.
Problem solving
2. What is the origin of the patterns on the surface of galvanized iron?
Answer :
The patterns appear due to the crystallization of zinc.
Output test
1. Complete the sentence.
“The dependence of physical properties on the direction inside the crystal is called...”
- anisotropy.
2. Fill in the missing words.
"Solid bodies are divided into ... and ..."
- crystalline and amorphous.
3. Find the correspondence between solids and crystals.
- 1a; 2b.
4. Find a correspondence between the substance and its state.
- 1b; 2c; 3b; 4a.
Output test
Output test
5. Find a correspondence between the bodies and the melting point.
- 1b; 2a.
You can find out more: http://ru.wikipedia.org/wiki; http://physics.ru/courses/op25part1/content/chapter3/section/paragraph6/theory.html; http://www.alhimik.ru/stroenie/gl_17.html; http://bse.sci-lib.com/article109296.html; http://fizika2010.ucoz.ru/socnav/prep/phis001/kris.html.
Crystalline
Many years ago in St. Petersburg, in one of the unheated warehouses, there were large stocks of white tin shiny buttons. And suddenly they began to darken, lose their shine and crumble into powder. Within a few days, the mountains of buttons turned into a pile of gray powder. “Tin plague” is the name given to this “disease” of white tin. And this was just a rearrangement of the order of atoms in tin crystals. Tin, passing from a white variety to a gray one, crumbles into powder.
Both white and gray tin are tin crystals, but at low temperatures their crystal structure changes, and as a result, the physical properties of the substance change. Both white and gray tin are tin crystals, but at low temperatures their crystal structure changes, and as a result, the physical properties of the substance change.
Anisotropy is observed mainly in single crystals. In polycrystals (for example, in a large piece of metal), anisotropy does not appear in the normal state. Polycrystals consist of a large number of small crystal grains. Although each of them has anisotropy, due to the disorder of their arrangement, the polycrystalline body as a whole loses its anisotropy.
The arrangement of particles in a crystal can be disrupted only if it begins to melt. As long as there is an order of particles, there is a crystal lattice, a crystal exists. If the structure of the particles is disrupted, it means that the crystal has melted - turned into liquid, or evaporated - turned into steam.
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Let's do an experiment. We will need a piece of plasticine, a stearin candle and an electric fireplace. Let's place plasticine and a candle at equal distances from the fireplace. After some time, part of the stearin will melt (become liquid), and part will remain in the form of a solid piece. During the same time, the plasticine will soften only a little. After some time, all the stearin will melt, and the plasticine will gradually “corrode” along the surface of the table, softening more and more. Let’s do the experiment. We will need a piece of plasticine, a stearin candle and an electric fireplace. Let's place plasticine and a candle at equal distances from the fireplace. After some time, part of the stearin will melt (become liquid), and part will remain in the form of a solid piece. During the same time, the plasticine will soften only a little. After some time, all the stearin will melt, and the plasticine will gradually “corrode” along the surface of the table, softening more and more
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Let's do the following experiment. Throw a piece of resin or wax into a glass funnel and leave it in a warm room. After about a month, it turns out that the wax has taken the shape of a funnel and even began to flow out of it in the form of a “stream” (see picture). In contrast to crystals, which retain their own shape almost forever, amorphous bodies exhibit fluidity even at low temperatures. Therefore, they can be considered as very thick and viscous liquids. Let's do the following experiment. Throw a piece of resin or wax into a glass funnel and leave it in a warm room. After about a month, it turns out that the wax has taken the shape of a funnel and even began to flow out of it in the form of a “stream” (see picture). In contrast to crystals, which retain their own shape almost forever, amorphous bodies exhibit fluidity even at low temperatures. Therefore, they can be considered as very thick and viscous liquids.
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All deformations of solids are reduced to tension (compression) and shear. With elastic deformations, the shape of the body is restored, but with plastic deformations it is not restored. All deformations of solids are reduced to tension (compression) and shear. With elastic deformations, the shape of the body is restored, but with plastic deformations it is not restored. Thermal motion causes vibrations of the atoms (or ions) that make up a solid. The amplitude of the vibrations is usually small compared to the interatomic distances, and the atoms do not leave their places. Since the atoms in a solid are connected to each other, their vibrations occur in concert, so that a wave propagates through the body at a certain speed.
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Similarities and differences. In physics, only crystalline bodies are usually called solids. Amorphous bodies are considered to be very viscous liquids. They do not have a specific melting point; when heated, they gradually soften and their viscosity decreases. Crystalline bodies have a certain melting point, unchanged at constant pressure. Amorphous bodies are isotropic—the properties of the bodies are the same in all directions. Crystals are anisotropic. The properties of crystals are not the same in different directions.
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Crystals. Studying the internal structure of crystals using X-rays made it possible to establish that the particles in the crystals have the correct arrangement, i.e. form a crystal lattice. - The points in the crystal lattice corresponding to the most stable equilibrium position of the particles of a solid are called crystal lattice nodes. In physics, a solid means only those substances that have a crystalline structure. There are 4 types of crystal lattice: ionic, atomic, molecular, metal. 1. the nodes contain ions; 2.atoms; 3.molecules; 4.+ metal ions
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Amorphous bodies. Amorphous bodies, in contrast to crystalline bodies, which are characterized by long-range order in the arrangement of atoms, have only short-range order. Amorphous bodies do not have their own melting point. When heated, amorphous bodies gradually soften, its molecules change their nearest neighbors more and more easily, its viscosity decreases and, with sufficient high temperature it can behave as a low-viscosity liquid.
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Types of deformation. A change in the shape and size of a body is called deformation. The following types of deformation exist: 1. deformation of longitudinal tension and longitudinal compression; 2. deformation of all-round tensile and all-round compression; 3.transverse bending deformation; 4.torsional deformation; 5.shear deformation;
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Each of the described types of deformation may be greater or lesser. Any of them can be assessed by absolute deformation ∆a numerical change in any size of a body under the influence of force. Relative deformation Ɛ (Greek epsilon) is a physical quantity that shows what part of the original size of the body a is the absolute deformation ∆a: Ɛ=∆L/L Ɛ= ∆a / a Mechanical stress is a quantity characterizing the action internal forces in a deformed solid. σ= F / S [Pa]
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Hooke's law. Elastic modulus. Hooke's law: mechanical stress in an elastically deformed body is directly proportional to the relative deformation of this body. σ=kƐ Value k characterizing the dependence mechanical stress in material from the genus of the latter and from external conditions called the modulus of elasticity. σ=EƐ σ=E (∆L/L) E – elastic modulus “Young’s modulus”. Young's modulus is measured by the normal stress that must arise in the material when a relative deformation equal to unity, i.e. when the sample length is doubled. The numerical value of Young's modulus is calculated experimentally and entered into the table. Thomas Young
