General information about building materials and their basic properties. General information about materials and their properties
At technology lessons, children learn to process not only fabric, paper and cardboard, but also various parts of plants, minerals, artificial materials and waste materials - waste from consumer goods, etc. Children collect them on excursions, bring them in the form of semi-finished products and blanks or ready-made ones. industrial products.
Natural materials include plant branches, leaves, flowers, seeds, roots, bark, moss, fruits, river and sea stones, sand, clay, also animal parts - fish bones, mollusk shells and shells, dried insects, poultry egg shells, feathers. In the form of semi-finished products, boards of various sizes are used in lessons.
From artificial materials For work, students often use plasticine, plastic, plywood, fiberboard, soft sheet metals, pieces of plastic, ceramics.
Finished industrial products include such waste materials as packaging, boxes, ribbons for decorating gifts and bouquets, jars, bottles, accessories for decorating clothes and premises.
Processing the listed materials is impossible without special knowledge of materials science and processing technology. Children acquire such knowledge through observation and experimentation.
In the first grade, it is necessary to carry out the following observations: determining the shape and color of leaves, acorns, nut shells, comparing the properties of sand and clay, wood and metal, identifying artistic expressive features in folk toys, etc.
In the second grade, observations of the properties of cones, bark, and branches are carried out. Features of processing soft and hard materials are revealed.
In the third grade, students observe the properties of dried plants, straw, and identify the properties of ceramics, plastics, and glass. Students learn to choose the best ways processing of these materials.
In the fourth grade, work is underway to generalize and deepen existing knowledge. Students independently choose the best methods of processing materials, develop the simplest technological maps for creative projects.
The teacher provides thorough instruction in the collection, storage and pre-processing of various materials. Special attention is given hygienic requirements, as well as safety rules for the collection, transportation and storage of materials. In addition, the teacher is obliged to point out that in our country there is an environmental protection law, which obliges us to take care of natural resources. It is not recommended to use ready-made products that have undergone special processing and are suitable for human consumption (cereals, pasta, flour, legumes). Only products that have expired are used for work.
Special tools are selected to work with different materials.
Marking and measuring tools.
Pencils– to mark parts on wood, grade 2 hard pencils are required T and 3 T. The sharpening angle of the pencil should be sharp. When marking, the pencil must be held at a slight angle in the direction of its movement and pressed firmly against the edge of the template or ruler;
Rulers– a metal ruler or tape measure is usually used for measurements. To mark on wood, it is more convenient to use a thick wooden ruler or a carpenter's square. Marking of round parts is done with a carpenter's compass. Marking straight lines on metal is carried out using a scriber, on wood - with a thicknesser.
Cutting tools.
Scissors– in the processing process, office scissors are used more often and mechanic’s scissors are rarely used.
Knives– for work use well-sharpened knives with a short blade (90-100mm). To split wood, it is more convenient to use a mower - a knife with a shorter and thicker blade. During the cutting process, the knife is held obliquely, directing its movement index finger. Natural materials are cut on stands and backing boards.
Hacksaws and jigsaws– designed for sawing wood and metals. For convenience, the processed materials are clamped in a vice or clamp.
Wire cutters– used for biting off wire and thin twigs.
Stichel- a narrow cutter with a cross-sectional shape acute angle or arcs (angular and semicircular). Stikhel is used for finishing wood products (flat-relief carvings), linoleum (clichés for linocuts).
Installation tools.
Hammer– used for assembling products using nails. When working with a hammer, it is necessary to ensure that the student does not hit the fingers holding the nail.
Pliers and round nose pliers– used when working with wire. These tools are used to bend and twist the wire.
Awl– used for making holes in soft or easily machined materials. Piercing is performed on stands or backing boards.
Gimlet– designed for drilling holes in harder materials. Work with a gimlet is performed on stands or backing boards.
Glue brush– must be tough. The width of the brush is selected according to the size of the surface of the connecting part.
Connecting parts and materials.
Nails– Large nails are not used in labor lessons. More often they use numbers 1, 2, 3, 4, which corresponds to the length of the nail in centimeters.
Pin– a rod for a fixed connection of parts. The pin can be easily made from a match, a twig or a strip of paper. A pin is used to connect parts made of acorns, cones, and molded materials.
Glue– for connection natural materials use PVA glue, casein or wood glue. It is better to glue floating models with casein glue, PVA, BF, Moment glue. Gluing parts requires great care. Glue is applied to thin material or the glued part of the surface of a smaller part. Dry leaves are spread with glue from the center of the leaf to the edges. Glue the smeared leaves carefully after they have absorbed some of the moisture. Glue is applied to narrow and deep surfaces using the tip of an awl dipped in glue.
The task of a technology teacher is not only to provide students with tools and all necessary materials, but also keep them in good condition. Knives and scissors must be properly sharpened, the tips of the awls and gimlets must not be broken, the jigsaw file must be well tensioned and ring like a string when touched with a finger, the hinge joints of the scissors and the gravel must be in good working order, the striking part of the hammer must be well secured to the handle. At each lesson, the teacher is required to instruct students on the rules for safe work with tools and certain materials.
Processed materials.
Wood– most often used in the work of high school students. IN primary school The wood used is pine, spruce, birch, linden, as well as three-layer plywood made from them. The wood is cut transversely with a hacksaw and jigsaw. The ends of the sawn wood are cleaned with files and sandpaper. Color wooden crafts oil paint.
In elementary school, students make pointers, eker, and labels for the classroom plot. Design specifications are required for the manufacture of such products. For example, boards for labels must correspond to the specified dimensions, their edges must be sanded; the pegs must correspond to the specified dimensions in length and thickness, their surface must be processed with a file and sandpaper.
Straw– dried stems of cereal plants; straw of wheat, rye, and oats is often used. Before work, the straw must be processed - nodes removed, internodes sorted by length and thickness. To make straw ribbon, the blanks are poured hot water for a day, then each straw is cut lengthwise and ironed with a hot iron on a wooden backing board. Depending on the temperature of the iron, the straw takes on different color shades. Straw is used to make appliqués and is used for inlaying wood products. Store straw in a dry, ventilated place.
Egg shells– an excellent material for the manufacture of volumetric and flat products. She colors well food coloring, shell parts are fixed with glue or plasticine. To make bulk products from eggs, you need to remove the contents using a medical syringe. The egg is also filled with heated paraffin using a syringe. By decorating the egg with various finishing details, you can make figurines of animals, birds, fish, etc. You can make a mosaic panel from painted eggshells by first covering the surface to be filled with a layer of plasticine.
Plant leaves– used in dried form. Leaves are collected in the fall and sorted by size, color, and shape. The leaves are dried under pressure or thermally (ironed with an iron). Store the finished material in a dry place.
Birch bark- a favorite material of folk craftsmen. Birch bark is collected in spring or early summer and cleaned of adhering particles. For ease of processing, birch bark is steamed in hot water, divided into layers, cut into the desired shapes. Dry the material in a cool, dry place.
Metals and alloys- in lessons they often use thin soft wire, soft tin, foil made of aluminum, copper, brass, zinc, tin, lead. Manual processing Metals in a cold state are called metalwork. Such materials can be easily processed with scissors, wire cutters, hammers, pliers and round nose pliers. The cut edges of the parts are processed with a file or sandpaper. The color of parts or a product can be changed by holding it over the flame of an alcohol lamp or by painting it with metal paints and varnishes.
Holes in thin sheet metal are made with an awl and punches. It is easy to make indentations on thin sheet metal and foil using stamps, ballpoint pen and master the simplest embossing techniques. Thin sheet metal can be bent and twisted using a hammer, pliers, or round nose pliers.
Wire can be shaped into rings, polygons, spirals, etc. Wire can be used to make flat contour shapes and three-dimensional products, as well as frames for soft toys. Thin wire can also be used as a connecting material.
Molding materials- clay, plasticine, plastic, gypsum, salty dough. Currently they can be purchased in stores. Clay can be mined and prepared to work with students.
Fat clay is suitable for modeling. Lean clay contains a large amount of impurities and is suitable for use after special processing– exhaustion. Clay is prepared in the summer, dried, crushed and sifted. The crushed clay is placed in a large vessel (tub, tank), filled with water and mixed thoroughly. The floating impurities are removed. Heavy impurities (pebbles, sand) settle to the bottom, and small particles of clay remain suspended. This liquid composition is poured into another container, leaving large impurities at the bottom. After some time, the clay settles to the bottom. Water is drained from the surface. This process is called elutriation.
Before starting work, the clay is filled with water and mixed. A well-prepared mass should not stick to your hands. Roll the prepared clay into a sausage 10 cm long and 1 cm thick and lift it by one end. If the sausage does not fall apart, then the clay is ready for use. To improve the quality of clay, you can add paper fiber and vegetable oil. Clay is worked on a backing board. Cut clay with wire or fishing line. Products are sculpted by hand, finishing details are made using stacks or special stamps.
Parts made of molded materials are connected by smearing, pressing or pins. Products made from molded materials are painted with gouache mixed with PVA glue (1x1, 2x1), watercolor paints (honey), varnished, or glazed (a glossy glassy alloy fixed by firing, which coats the surface of the product). Dry the products in muffle furnaces, on radiators or on a well-ventilated surface.
Plastics– chemical production products. In elementary grades, easily processed plastics are used - organic glass, foam rubber, polystyrene foam, linoleum, nylon, etc. Plastic blanks are processed by cutting, drilling, they can be painted, joined with glue, and stitched. Toys and souvenirs are made from foam rubber and polystyrene. Foam rubber can be used to stuff soft toys.
Linoleum used for making appliques or clichés. Clichés for linocuts are made using stichels. Apply paint (gouache, printing ink) to the finished surface of the cliche with a roller, place a clean sheet of paper and iron it with a smooth object. A print is made, called a print.
Waste materials– packaging boxes, corks, reels, tubes of cream, toothpaste, synthetic nets used for packaging vegetables, bouquets, empty rods, tubes, etc. Making useful things from waste materials accustoms students to frugality, develops their creativity, imagination, and ingenuity.
Papier mache- the most accessible technique for making three-dimensional products in primary school. For work you will need: newsprint, paste, gouache. Utensils, toys, and homemade molds made from plasticine are suitable as molds for making three-dimensional products. The paste for work is made from starch or flour. Products are dried in well-ventilated and warm places. Uneven places on the forms are smoothed with sandpaper. Painting of products is done with gouache paints mixed with PVA glue in the ratio: 2 parts paint and 1 part glue.
Features of processing various materials, methods for studying their properties are described in numerous teaching aids, books on decorative and applied arts, magazines on design and handicrafts, in books by V.A. Baradulina, A.M. Gukasova, N.M. Konysheva, V.P. Kuznetsova and others.
Control questions.
1. What materials are called natural?
2. What are the features of storing various materials?
3. By what principle is the selection of various materials for working with students carried out? primary classes?
4. What connecting materials are used to assemble products from natural materials?
Assignments for independent work.
1. Find (in printed or electronic sources) and study material containing information about the properties of natural materials, methods of their preparation and storage, and processing techniques.
2. Select literature that covers manufacturing technologies for products made from various materials.
Laboratory work assignments.
1. Analyze the content of the module: “Technology of processing of structural materials and mechanical engineering” in the “Technology” program. Highlight the skills and abilities that the authors of the program recommend developing in primary school students in the process of processing various materials.
2. Develop a plan for conducting an experiment for 3rd grade students to observe the properties of one of the specific natural materials.
3. Develop a lesson summary aimed at studying methods of processing one of the artificial materials.
4. Make 1 sample of products from natural materials, artificial materials and waste materials to demonstrate them in technology lessons in primary school.
5. Develop instructional cards to teach students how to assemble one of the products from various materials.
General information about materials and their properties
BRIEF INFORMATION ABOUT BUILDING MATERIALS
General information about materials and their properties
Types of basic building materials. The main building materials include: forest, natural stone, ceramic materials and products, inorganic (mineral) binders (cement, clay, alabaster, etc.) and products made from them, mortars for masonry and plaster, artificial stone materials and products based on binders, bitumen and thermal insulation materials, construction metals, metal products and paints and varnishes. IN Lately Various materials made from plastics are widely used in construction.
Basic properties of building materials. For correct application it is necessary to know physical-mechanical and Chemical properties building materials listed below.
Density - the mass of a unit volume of material in an absolutely dense state without pores and voids, kg/m3,
where is the mass of the sample, kg; - volume of the sample in an absolutely dense state, m3.
Relative density is the ratio of the density of a building material in its natural state (with pores) to the density of an absolutely dense body or the ratio of the volume of a material in an absolutely dense state to its external volume in its natural state, rel. units,
Relative density can also be expressed as a percentage:
Bulk density is the mass per unit volume of loose material poured into any container without compaction.
Porosity is the degree to which the volume of a material is filled with pores.
The relative density and porosity add up to unity, i.e.
Or 
Water absorption is the ability of a material to absorb and retain water. Water absorption is determined by the difference in the mass of a material sample in a water-saturated state and in an absolutely dry state and is expressed as a percentage of the mass of the dry material.
Humidity is the water content in the material (by mass), expressed in %.
Water permeability is the ability of a material to pass water under pressure. The degree of water permeability is measured by the amount of water passing through 1 m 2 of the surface of the material in 1 s at a given constant pressure.
Frost resistance is the ability of a material in a water-saturated state to withstand repeated alternating freezing and thawing without noticeable signs of destruction and without a significant decrease in strength. The durability of many building elements depends on the frost resistance of the material.
Thermal conductivity is the ability of a material to transmit through its thickness a heat flow that occurs when there is a temperature difference on the surfaces bounding it. Thermal conductivity is measured in kilojoules (kJ).
The total amount of heat, kJ, passed through the fence can be expressed by the formula
where is the thermal conductivity coefficient of the material, kW/m °C;
Fencing area, m2;
Fencing thickness, m;
Temperature difference on opposite surfaces of the fence, °C;
Time, s.
Assuming , , , , we obtain the value of the thermal conductivity coefficient
which for of this material depends on its physical properties (porosity, humidity, density, etc.)
Heat capacity is the property of a material to absorb heat when heated and release it when cooled. Heat capacity is measured by the coefficient of heat capacity C (sometimes called specific heat capacity), which is the amount of heat in J required to heat 1 kg of a given material by 1°C.
Fire resistance - the ability of materials to withstand action without destruction high temperatures. Based on fire resistance, building materials are divided into three groups:
Fireproof (concrete, brick), under the influence of fire or high temperature do not ignite, do not smolder or char;
Resistant to combustion (fibrolite, asphalt concrete), when exposed to fire or high temperature, it is difficult to ignite, char or smolder; after the fire is removed, smoldering stops;
Combustible materials (wood, etc.) ignite under the influence of fire and continue to burn or smolder after the source of fire is removed. Some materials in this group ignite when exposed to high temperatures.
Fire resistance is the ability of materials to withstand prolonged exposure to high temperatures without softening or deforming.
Chemical resistance is the ability of materials to resist the action of acids, alkalis, and salts dissolved in water.
Strength - the ability of a material to resist destruction under the influence of internal stresses arising in it from load or other factors and causing compression, tension, shear, bending or torsion. For example, the strength of a material under compression and tension is assessed by the value of the ultimate strength R, Pa, determined by the formula
F is the cross-sectional area of the sample, m2.
Thus, the ultimate strength is the stress corresponding to the load that causes destruction of a material sample.
Hardness is the ability of a material to resist the penetration (introduction) of another, harder body into it.
Elasticity is the ability of a material to deform and again restore its original shape and size after removing the load, under the influence of which it changed to one degree or another.
Plasticity is the ability of a material, under the influence of loads acting on it, to change its size and shape within significant limits without the formation of cracks or loss of strength, and to maintain the adopted shape after their removal.
Fragility is the property of a material to collapse suddenly under the influence of external forces, without preliminary deformation.
Produced building materials must comply with state standards (GOSTs), which are officially approved documents that contain Full description material, product or part. GOSTs establish the requirements that building materials must meet and the rules for their acceptance.
Forest materials
The structure of wood. When examining a cross-section of a tree trunk, the following parts can be distinguished: bark, cambium, wood itself and pith.
The bark consists of an outer layer - the rind and an inner layer - the bast. Beneath the phloem layer is a thin layer of cambium. Located behind the cambium thick layer wood, consisting of a series of thin concentric rings. Each such ring corresponds to one year of the tree’s life and is called an annual ring.
In the center of the trunk is the core. In pine, oak and cedar, the core has a darker color; in spruce, fir, and beech, the central part of the trunk does not differ in color from the outer part and is called “ripe wood.” There are tree species that do not have a core (birch, maple, alder); Such species are called sapwood.
Properties of wood. Humidity. Great influence on technical properties wood is affected by its moisture content. According to the degree of humidity, wood is distinguished: wet (humidity is greater than that of freshly cut wood), freshly cut wood (humidity 35% or more), air-dry (humidity 20-15%) and room-dry (humidity 13-8%).
Shrinkage and swelling. Changes in the moisture content of wood cause a change in its volume, which leads to shrinkage or swelling. Due to the heterogeneity of the structure, wood dries out and swells in different directions unevenly, which entails warping or cracks in structures. Therefore, you should use wood with a moisture content appropriate to its operating conditions; For this purpose, natural or artificial drying is performed.
Mechanical properties of wood. The strength of wood in different directions is not the same. Thus, the tensile strength of wood along the grain is 20-30 times greater than across the grain. The same phenomenon is observed when wood is compressed.
The main tree species used in construction.
In construction, coniferous species are most used: pine, spruce, larch, fir, cedar. Deciduous species: oak, beech, ash, birch, maple, plane tree, pear, etc. - are used mainly for the manufacture of carpentry and for interior decoration buildings. In order to save valuable timber species, where possible, and especially for temporary and auxiliary construction, deciduous species such as alder, linden, aspen and poplar should be used.
Assortment of forest materials. Round timber, depending on its diameter at the upper end (cut), is divided into logs, logs and poles. The logs in the top cut must have a diameter of at least 120 mm, a sub-cut from 80 to 10 mm and poles from 30 to 70 mm. Lumber is obtained by longitudinal sawing of logs. Depending on the quality of the wood and the presence of defects, lumber from coniferous species are divided into 5 varieties.
The following types of lumber are used in construction (Fig. 2.1): plates, quarters, slabs, boards (width more than double thickness); bars and beams (width no more than double thickness). Depending on the cleanliness of the edges, boards are divided into unedged, semi-edged and edged.
The length of the boards and beams is set from 1 to 6.5 m with a gradation of 0.25 m. Depending on the processing method, the beams are distinguished: two-edged - sawn on both sides - and four-edged - sawed on four sides.
Introduction
Dear students, we are starting to study the course “General Materials Science”. The lectures that will be given during this semester will help you understand the physical and chemical essence of the structure and properties of various materials. You will learn why natural and artificially created materials have different thermal conductivity, mechanical and operational properties, how these properties are related to each other, how and within what limits they can be changed. At the same time as studying these issues, you will become more deeply acquainted with the physical and chemical properties of the elements, information about which is contained in the periodic table of D.I. Mendeleev. I would especially like to note that the structure of the atoms of chemical elements determines the structure and energy of the chemical bonds they form, which, in turn, underlie the entire complex of properties of substances and materials. Only by relying on an understanding of the chemical interaction of atoms can one control the processes occurring in substances and obtain specified performance characteristics.
However, more important than the study of individual problems presented in lectures is the opportunity provided to you to combine the basic principles of physics, chemistry and applied scientific fields (thermal physics, mechanics) for a comprehensive understanding of the interaction of substances and their properties.
The lectures focus on the fundamental principles of materials science due to the fact that modern materials science is aimed at obtaining materials with specified characteristics and serves as the basis for high-tech technologies of the 21st century.
Material called a substance that has the necessarya set of properties to perform a given function separatelyor in combination with other substances.
Modern materials science fully developed as a science in the second half of the 20th century, which was associated with the rapid increase in the role of materials in the development of engineering, technology and construction. The creation of fundamentally new materials with specified properties, and on their basis the most complex structures, allowed humanity to achieve unprecedented success in nuclear and space technology, electronics, information technology, construction, etc. in a short time. It can be considered that Materials Science - This is a section of scientific knowledge devoted to the properties of substances and their directed change in order to obtain materials with predetermined performance characteristics. It is based on the fundamental basis of all sections of physics, chemistry, mechanics and related disciplines and includes the theoretical foundations of modern high-tech technologies for the production, processing and use of materials. The basis of materials science is knowledge about the processes occurring in materials under the influence of various factors, their influence on the complex properties of the material, and ways to control and manage them. Therefore, materials science and materials technology are interrelated areas of knowledge.
The course of materials science and technology of building materials serves goals knowledge of the nature and properties of materials, methods of obtaining materials with given characteristics for the most effective use in construction.
Main goals studying the course:
To provide an understanding of the physical and chemical essence of the phenomena that occur in materials when they are exposed to various factors under production and operating conditions, and their influence on the properties of materials;
Establish the relationship between the chemical composition, structure and properties of materials;
Study the theoretical foundations and practice of implementing various methods of obtaining and processing materials that ensure high reliability and durability of building structures;
To provide knowledge about the main groups of non-metallic materials, their properties and areas of application.
The lectures cover:
Fundamentals of the interaction of atoms and molecules, which make it possible to further explain the influence of its chemical composition and targeted processing processes on the properties of the material;
The structure of a solid, defects in the crystal structure and their role in the formation of the properties of materials;
The phenomena of heat, mass and charge transfer, which form the essence of any technological process;
Theoretical foundations for obtaining amorphous structures of materials;
Elements of the mechanics of elastic and plastic deformation and destruction of the material, which underlie the formation of the strength and reliability of modern building materials and structures, as well as methods of their testing;
So, the task of modern materials science is to obtain materials with predetermined properties. The properties of materials are determined by the chemical composition and structure, which are the result of obtaining the material and its further processing. To develop materials and technologies, it is necessary to know the physical and chemical phenomena and processes occurring in the material at various stages of its production, processing and operation, their prediction, description and control. Thus, knowledge of the theory is necessary to create controlled technological processes, the result of which will be a material with clearly defined values of working properties.
The physicochemical properties of a substance are determined by the electronic structure of its atoms. The interactions of atoms are associated, first of all, with the interaction of their electronic shells. Therefore, when developing materials and processes for their production, it is necessary to clearly understand how various chemical elements donate and accept electrons, and how changes in the electronic state affect the properties of the elements.
Let's remember electronic structure of the atom.
Electronic structure of the atom
About two and a half thousand years ago, the ancient Greek philosopher Democritus expressed the idea that all the bodies around us consist of tiny invisible and indivisible particles - atoms.
Molecules are assembled from atoms, like from peculiar bricks: from identical atoms - molecules simple, substances made of atoms various types-molecules complex substances.
Already at the end of the nineteenth century, science established that atoms - particles are far from being “indivisible”, as ancient philosophy imagined, but, in turn, consist of even smaller and, so to speak, even simpler particles. At present, the existence of about three hundred elementary particles that make up atoms has been proven with greater or less certainty.
To study chemical transformations, in most cases it is enough for us to indicate the three particles included in the atom: proton, electron andneutron.
A proton is a particle with a mass conventionally taken as one (1/12 of the mass of a carbon atom) and a unit positive charge. Proton mass – 1.67252 x 10 -27 kg
An electron is a particle with practically zero mass (1836 times less than that of a proton) and a single negative charge. The electron mass is 9.1091x10 -31 kg.
A neutron is a particle with a mass almost equal to the mass of a proton, but without a charge (neutral). Neutron mass – 1.67474 x 10 -27 kg.
Modern science imagines the atom to be structured approximately in the same way as ours is tripled. solar system: at the center of the atom is core(the sun), around which electrons revolve at a relatively large distance (like planets around the sun). This “planetary” model of the atom, proposed in 1911 by Ernest Rutherford and refined by Bohr’s postulates in 1913, has retained its significance to the present day.
The bulk of the atom's mass is concentrated in the nucleus, which consists of protons and neutrons and occupies a very small part of the volume of the atom (the mass of electrons is usually not taken into account in chemical calculations of atomic and molecular masses).
The number of protons in the nucleus determines view atom. In total, more than a hundred types of atoms have now been discovered, which are presented in the Table of Elements under numbers corresponding to the number of protons in the nucleus.
The simplest atom contains only one proton in the nucleus: this is a hydrogen atom. A more complex helium atom already has two protons in its nucleus, a third (lithium) has three, etc. A certain type of atom is called an element.
2. Structure and properties of finishing materials
Internal structure of materials
Depending on the state of aggregation and stability, solids can have a strictly ordered structure - crystalline, or a disordered, chaotic structure - amorphous.
The nature of the particles located at the nodes of the crystal lattice and the prevailing interaction forces (chemical bonds) determine the nature of the crystal lattice: atomic with covalent bonds, molecular with van der Waals and hydrogen bonds, ionic with ionic bonds, metallic with metal bonds.
Atomic lattice consists of neutral atoms linked together by covalent bonds. Substances with covalent bonds are characterized by high hardness, refractoriness, and insolubility in water and most other solvents. Examples of atomic lattices are diamond and graphite. The energy of covalent bonds ranges from 600 to 1000 kJ/mol
Molecular lattice built of their molecules (I 2, Cl 2, CO 2, etc.), connected to each other by intermolecular or hydrogen bonds. Intermolecular bonds have a small energy value, no more than 10 kJ/mol; Hydrogen bonds are somewhat larger (20-80 kJ/mol), therefore substances with a molecular lattice have low strength, low melting point, and high volatility. Such substances do not conduct current. Substances with a molecular lattice include organic materials, noble gases, and some inorganic substances.
Ionic lattice formed by atoms that differ greatly in electronegativity. It is characteristic of compounds of alkali and alkaline earth metals with halogens. Ionic crystals can also consist of polyatomic ions (for example, phosphates, sulfates, etc.). In such a lattice, each ion is surrounded by a certain number of its counterions. For example, in the NaCl crystal lattice, each sodium ion is surrounded by six chlorine ions, and each chlorine ion is surrounded by six sodium ions. Due to the non-directionality and unsaturation of the ionic bond, the crystal can be considered as a giant molecule, and the usual concept of a molecule here loses its meaning. Substances with an ionic lattice are characterized by a high melting point, low volatility, high strength and significant energy of the crystal lattice. These properties bring ionic crystals closer to atomic ones. The binding energy of the ionic lattice is approximately equal, according to some sources, less than the energy of the covalent lattice.
Metal gratings form metals. There are metal ions at the lattice sites, and the valence electrons are delocalized throughout the crystal. Such crystals can be considered as one huge molecule with a single system of multicenter molecular orbitals. The electrons are in the bonding orbitals of the system, and the antibonding orbitals form the conduction band. Since the binding energy of the bonding and antibonding orbitals is close, electrons easily pass into the conduction band and move within the crystal, forming, as it were, an electron gas. In table 3.1 shows, as an example, the binding energies for crystals with different types communications.
The ordered arrangement of particles in a crystal is maintained over long distances, and in the case of ideally formed crystals, throughout the entire volume of the material. This orderliness of the structure of solids is called long-range order.
Kazakova Z.K.
Project for children 4-5 years old
“Properties and qualities of materials”
PROBLEM:
Children by the term “material” only mean fabric. Although most of the man-made objects around us are made from materials such as plastic, glass, wood, and paper. Children do not know about the properties of these materials, the peculiarities of handling them, they do not know their intended purpose and the functions of objects made from them.
TARGET:
To form in children ideas about such materials of the man-made world as paper, plastic, wood, glass.
TASKS:
1. Teach children to identify the characteristics of materials, their properties and qualities; classify objects of the man-made world according to material.
2. To acquaint children with the intended purpose of objects of the man-made world, depending on the properties and qualities of the material from which they are made.
3. With children, draw up rules for handling objects, depending on the material from which they are made.
4. Organize children’s activities to create a collection “Diversity of Paper”.
5. Expand and activate children’s vocabulary with the characteristics of signs of materials in the man-made world.
6. 
Develop children's social skills: the ability to work in a group, negotiate, take into account the opinion of a partner.
ACTIVITY:
1. Collecting materials for the project piggy bank.
2. Educational sessions on the following topics:
· “The History of the Discovery of Glass”
· “Paper making”
· “Transforming wood into building material”
"The Emergence of Plastic"
3. Guessing riddles and reading fiction O different materials and objects of the man-made world made from them.
4. Artistic and creative activities:
· children making paper lanterns for the Christmas tree;
· making “bunny ears” hats from cardboard.
5. Organization role-playing game“Shop” (“Furniture”, “Toys”, “Dishes”, “Stationery”)
6. Organization of the didactic game “My Apartment”.
7. Conducting experiments:
· “Drowning - not sinking”
· “It beats - it doesn’t beat”
· “What is visible through glass (transparent, frosted, colored)”
· “Wrinkles - doesn’t wrinkle”
8. Organization of an exhibition of objects of the man-made world made of paper, plastic, wood, glass.
STAGES OF WORK ON THE PROJECT
Istage – PIGGY BANK
v objects of the man-made world (made of paper, wood, plastic, glass);
v illustrations of various objects of the man-made world (made of paper, wood, plastic, glass);
v artistic word about materials and objects of the man-made world (poems, riddles, sayings, stories, etc.).
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IIstage – CREATION OF A CARD INDEX
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Algorithm for creating a card index
Objects of the man-made world made of paper
Objects of the man-made world made of wood
Objects of the man-made world made of plastic
Objects of the man-made world made of glass
IIIstage – MODEL
Based on the knowledge gained, a “Model of Hand-Made Materials” was developed together with the children.
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IVstage – PRODUCT
The product of this project is an exhibition of objects of the man-made world from various materials: “Plastic Kingdom”, “Glass Kingdom”, “Wooden Miracle”, “Paper Country”.
Vstage – PROJECT PRESENTATION
Children of group No. 11 are invited.
Children participating in the project tell:
– There are many materials in the world: plastic, glass, wood, paper. We collected a collection of items from these materials, then distributed them into boxes - we created a card index by materials. And today we present to you their exhibition.
Dear guests, please come to our exhibition.
Children of the group and guests come to the table with plastic objects.
– This is the “Glass Kingdom”.
Children talk about the signs of glass and read poems:
Everything is visible through the glass:
And the river and the meadows,
Trees and cars
People, dogs, houses.
With a glass bunny
I love to play.
I know he's fragile
I won't drop him.
fragile, transparent,
Looks solid.
It will cover you from the wind,
It will insulate you from the cold.(Glass)
Children of the group and guests come to the table with wooden objects.
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– This is the “Wooden Miracle” exhibition.
Children talk about the signs of a tree and read poems:
Wooden box
It's on the nightstand.
Mommy's beloved
Keeps rings in it.
Wooden chest
So beautiful and bright.
Dad often leaves him
He takes out a gift.
There is a painted board hanging,
She's a helper, we know:
Helped us cut vegetables
That's what it's for.
Children of the group and guests come to the table with paper objects.
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– This is the “Paper Country” exhibition.
Children talk about the signs of paper and read poems:
Paper butterflies,
paper elephants,
Bunnies and Christmas trees,
Children need it so much!
Paper boats
I like to let it go myself.
Paper boats
They float along streams.
Song "Paper Country"
(music by I. Nikolaev)
There are beyond the seas, beyond the mountains
Paper country.
There are streets and walls made of paper
Furniture and everything at home.
Residents wear paper
Hats and umbrellas.
The paper world is ruled
Paper adults.
Chorus: paper country,
Paper country.
We'll tell you
We'll show you
Here she is, here she is!
(Children point to “Paper Land”)
CONTINUATION OF THE PROJECT
Introducing children to other materials of the man-made world, such as fabric, metal, rubber, polyethylene.
