Presentation "crystalline and amorphous bodies". Amorphous bodies and crystal lattices Crystalline and amorphous bodies presentation 10

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Let's do an experiment. We will need a piece of plasticine, a stearine 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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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.

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;

    • developing-

  • 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;

    • educational -

  • cultivate a scientific worldview.

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

Indications

dry thermometer, °C

Reading difference

dry and wet thermometers, °C

Wet thermometer readings, °C

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 the correspondence between the state of aggregation of a substance 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 TVs provide very high quality images, consuming a negligible amount of energy from a small 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

Class: 10

Lesson type: explanation of new material

Lesson objectives:

  • Educational: repeat and systematize knowledge about the properties of crystals, consider the features of amorphous bodies, make comparisons, introduce the concepts of “isotropy”, “anisotropy”, “polycrystal”, “monocrystal”.
  • Educational: development of interest in physics and mathematics, development of logical thinking, attention, memory, independence in finding solutions.
  • Educational: formation of a scientific worldview, education of accuracy, mutual assistance.

Means of education:

  • Textbook “Physics. 10th grade" Gendenshtein L.E.
  • Collection of problems in physics. Gendenshtein L.E.
  • Projector, computer, video materials (Appendix 1).
  • Demonstration equipment - a model of a crystal lattice, samples of mica and quartz crystals.
  • Laboratory equipment - microscopes, samples of substances - salt, sugar, sugar candy.

Teaching methods:

  • Verbal (teacher explanation)
  • Visual (video)
  • Practical (experimental research - observation through a microscope, problem solving)

Lesson plan:

  1. Org. moment
  2. Updating and motivating knowledge (repetition)
  3. Explanation of new material
  4. Consolidation
  5. Summarizing. Homework

During the classes

1. Org. moment.

2. Let me remind you that we continue to study molecular kinetic theory.

– What is the main task of the MCT? (Answer: MCT explains the properties of macroscopic bodies based on knowledge about the structure of matter and the behavior of molecules).

We examined in detail in previous lessons the features of gases and liquids. To complete MCT, we need to consider the features of solids.

– What features about the structure of solids do we know from the physics course? (Answers: the molecules are located very close to each other, the interaction forces between the molecules are large, the molecules vibrate around their equilibrium positions).

– What are the differences in the structure of liquids and solids? (Answer: in the forces of interaction between molecules, in the arrangement of particles, in the speeds and types of movement of molecules).

So, the main feature is the correct arrangement of atoms, i.e. the presence of a crystal lattice, which is why most solids are called crystalline. However, there is another group of solids that we have not talked about before - these are amorphous bodies. So, the topic of today's lesson is “Crystalline and amorphous bodies.” (Slide 1)(Annex 1)

3. We know some properties of crystals. Remember what can be said about the shape and volume of solids? (Answer: both shape and volume are preserved)

To systematize knowledge about solids and to compare crystals and amorphous bodies during the lesson, we will fill out the following table (the table is prepared in advance on the board or can be displayed on the screen via a computer):

Draw a table in your notebook.

In the “Crystalline bodies” column, write down what we know about the shape and volume of crystalline bodies.

(Slide 2)

The figure shows the crystal lattices of various substances. Please note that the lines connecting the positions of the atoms form regular geometric shapes: squares, rectangles, triangles, hexagons, etc.

Those. crystals are solids whose atoms are arranged in a certain order (write in the table).

The correct arrangement of atoms is clearly demonstrated by the crystal lattice model.

Demonstration models of the graphite crystal lattice.

(Slide 3) From chemistry lessons you know that crystal lattices can consist not only of neutral atoms, but also of ions. The figure shows ionic crystal lattices of table salt and cesium chloride. In this case, we again observe the correct arrangement of particles in space.

(Slide 4) It happens that the same atoms form different substances with completely different properties depending on the type of crystal lattice: on the left is a layered lattice of graphite (a model of which we just saw). Graphite is a soft, opaque, conductive substance. On the right is a diamond with a cascading lattice consisting of the same carbon atoms. Diamond is a transparent crystal, a dielectric, the strongest substance in nature.

(Slide 5) Graphite and diamond.

The consequence of the correct arrangement of atoms is the presence of flat faces and the correct geometric shape of crystals (regardless of size), symmetry. Please note this on the following slides:

(Slide 6) Lead iodide. The sizes of the crystals are different, but the shape is the same. In addition, if the crystal splits into pieces, they will all be of the same shape.

(Slide 7) Diamonds

(Slide 9) Snowflakes.

(Slide 10) Quartz.

Study. You have various substances and microscopes on your table. Set up the light in the microscope, place grains of salt on a glass slide and examine them. Which of the already listed features of crystals is confirmed by observing salt crystals? (Correct shape in the form of cubes, flat edges are visible).

Inside a crystal, the distances between atoms in different directions are different, and therefore the interactions between atoms are different. Let's think about what this leads to.

Let's look at the graphite lattice model again.

– Where are the atoms more strongly connected: in individual layers or between layers? (Answer: in separate layers, since the particles are closer to each other).

– How can this affect the strength of the crystal? (Answer: Strength will likely vary.)

– In which direction will heat be transferred faster - along the layer or in the perpendicular direction? (Answer: along the layer).

So, the physical properties are different in different directions. It is called anisotropy . Let's write it in the table: crystals anisotropic, i.e. their physical properties depend on the direction chosen in the crystal(thermal conductivity, electrical conductivity, strength, optical properties). This is the main property of crystals!!

Demonstration pieces of mica and its ability to easily delaminate, but at the same time it is difficult to tear the mica plate across the layers.

(Slide 11) Let's consider another feature of crystals.

– How are these two objects different? (Answer: on the left is sugar in the form of individual grains, and on the right are fused crystals).

Single crystals are called single crystals , and a lot of crystals soldered to each other - polycrystals (write in the table).

(Slide 12) Examples of single crystals are precious stones (sapphires, rubies, diamonds). This is what a ruby ​​crystal looks like in nature.

(Slide 13) For jewelry, they are given an additional cut. All metals are classified as polycrystals.

(Slide 14) And here is sugar in three states: granulated sugar, refined sugar, and sugar candy.

– Are there single crystals among these samples? (Answer: granulated sugar).

– Is there a polycrystal among these samples? (Answer: refined sugar).

– Can we say that the lollipop has the correct shape? Does it have flat edges? (Answers: no).

Study. Examine grains of sugar and pieces of candy through a microscope. What can be said about the shape of the grains, the presence of flat edges, and the repeatability of the shape in different grains? (answer: sugar grains have all the characteristics of crystals, candy grains do not).

(Slide 15) Here are photographs taken with a microscope: on the left is a grain of granulated sugar, on the right is a piece of candy. Note the chip of the candy.

Unlike crystals, sugar candy can split and soften, gradually turning into a liquid state, while changing shape. All amorphous bodies are substances whose atoms are arranged in a relative order; there is no strict repeatability of the spatial structure.(Slide 16) The consequence of this is isotropy– identical physical properties in different directions (write in the table).

(Slide 17) Another example of a substance in crystalline and amorphous states (sand and glass). It is important that due to different distances between atoms, even in neighboring cells, the spatial lattice will not collapse at a certain temperature, as happens in crystals. For amorphous bodies, there is a temperature range at which the substance smoothly transforms into a liquid state.

(Slide 18) Examples of amorphous bodies are resin, rosin, amber, plasticine and others .

4. For consolidation material we answer questions No. 597, No. 598 from the collection of problems of Rymkevich A.P., No. 17.26, 17.30 from the collection of problems of L.E. Gendenstein.

If there is time left, we solve problems from the Unified State Exam (A10, A11).

5 . Homework: Fill out the table to the end, §30.

 

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