Math lesson notes

Lesson notes.

Equipment and materials:
Demo material: subject pictures: hut, Christmas tree, snowman; "Number 4"; “What does the number 4 look like?” snowflakes;
Handout: TVET by M. V. Korepanova “My Mathematics” (a manual for children 4-5 years old); cards with dots (1-4); sheets for individual work; colored pencils

Progress of the lesson

Applications

The world around us is material. There are two types of matter: substance and field. The object of chemistry is a substance (including the influence of various fields on the substance - sound, magnetic, electromagnetic, etc.)

Matter is everything that has rest mass (i.e. is characterized by the presence of mass when it is not moving). So, although the rest mass of one electron (the mass of a non-moving electron) is very small - about 10 -27 g, but even one electron is matter.

The substance comes in three states of aggregation– gaseous, liquid and solid. There is another state of matter - plasma (for example, there is plasma in thunderstorms and ball lightning), but in school course Plasma chemistry is almost not considered.

Substances can be pure, very pure (needed, for example, to create fiber optics), may contain noticeable amounts of impurities, may be mixtures.

All substances are made up of tiny particles called atoms. Substances consisting of atoms of the same type(from atoms of one element), are called simple(for example, charcoal, oxygen, nitrogen, silver, etc.). Substances that contain atoms bonded to each other different elements, are called complex.

If a substance (for example, air) contains two or more simple substances, and their atoms are not connected to each other, then it is not called a complex substance, but a mixture of simple substances. The number of simple substances is relatively small (about five hundred), but the number of complex substances is enormous. To date, tens of millions of different complex substances are known.

Chemical transformations

Substances are able to interact with each other, and new substances arise. Such transformations are called chemical. For example, a simple substance, coal, interacts (chemists say it reacts) with another simple substance, oxygen, resulting in the formation of a complex substance, carbon dioxide, in which the carbon and oxygen atoms are interconnected. Such transformations of one substance into another are called chemical. Chemical transformations are chemical reactions. So, when sugar is heated in air, a complex sweet substance - sucrose (which sugar is made of) - turns into a simple substance - coal and a complex substance - water.

Chemistry studies the transformation of one substance into another. The task of chemistry is to find out with which substances a particular substance can interact (react) under given conditions and what is formed. In addition, it is important to find out under what conditions a particular transformation can occur and the desired substance can be obtained.

Physical properties of substances

Each substance is characterized by a set of physical and chemical properties. Physical properties are properties that can be characterized using physical instruments. For example, using a thermometer you can determine the melting and boiling points of water. By physical methods can characterize the ability of a substance to conduct electric current, determine the density of a substance, its hardness, etc. At physical processes substances remain unchanged in composition.

The physical properties of substances are divided into countable (those that can be characterized using certain physical instruments by number, for example, by indicating density, melting and boiling points, solubility in water, etc.) and innumerable (those that cannot be characterized by number or is very difficult - such as color, smell, taste, etc.).

Chemical properties substances

The chemical properties of a substance are a set of information about what other substances and under what conditions it enters into contact. chemical interactions this substance. The most important task chemistry - identifying the chemical properties of substances.

IN chemical transformations participate tiny particles substances - atoms. During chemical transformations, other substances are formed from some substances, and starting materials disappear, and instead of them new substances (reaction products) are formed. A atoms at everyone chemical transformations are preserved. Their rearrangement occurs; during chemical transformations, old bonds between atoms are destroyed and new bonds arise.

Chemical element

The number of different substances is enormous (and each of them has its own set of physical and chemical properties). Atoms that differ from each other in their most important characteristics in the environment around us material world relatively small - about a hundred. Each type of atom has its own chemical element. A chemical element is a collection of atoms with the same or similar characteristics. There are about 90 different types of chemical elements. To date, physicists have learned to create new types of atoms that are not found on Earth. Such atoms (and, accordingly, such chemical elements) are called artificial (in English - man-made elements). More than two dozen artificially obtained elements have been synthesized to date.

Each element has Latin name and a one- or two-letter character. In Russian-language chemical literature there are no clear rules for pronunciation of symbols of chemical elements. Some pronounce it like this: they call the element in Russian (symbols for sodium, magnesium, etc.), others - according to Latin letters(symbols of carbon, phosphorus, sulfur), the third - what the name of the element sounds like in Latin (iron, silver, gold, mercury). We usually pronounce the symbol of the element hydrogen H the way this letter is pronounced in French.

Comparison the most important characteristics chemical elements and simple substances are given in the table below. One element may correspond to several simple substances (the phenomenon of allotropy: carbon, oxygen, etc.), or perhaps just one (argon and other inert gases).

All substances are divided into simple and complex.

Simple substances- These are substances that consist of atoms of one element.

In some simple substances, atoms of the same element combine with each other to form molecules. Such simple substances have molecular structure. These include: , . All these substances consist of diatomic molecules. (Note that the names of the simple substances are the same as the names of the elements!)

Other simple substances have atomic structure, i.e. they consist of atoms between which there are certain bonds. Examples of such simple substances are all (, etc.) and some (, etc.). Not only the names, but also the formulas of these simple substances coincide with the symbols of the elements.

There is also a group of simple substances called. These include: helium He, neon Ne, argon Ar, krypton Kr, xenon Xe, radon Rn. These simple substances are made up of atoms that are not bonded to each other.

Each element forms at least one simple substance. Some elements can form not one, but two or more simple substances. This phenomenon is called allotropy.

Allotropy is the phenomenon of the formation of several simple substances by one element.

Different simple substances that are formed by the same chemical element are called allotropic modifications(modifications).

Allotropic modifications may differ from each other in molecular composition. For example, the element oxygen forms two simple substances. One of them consists of diatomic molecules O 2 and has the same name as the element-. Another simple substance consists of triatomic O 3 molecules and has proper name- ozone.

Oxygen O 2 and ozone O 3 have different physical and chemical properties.

Allotropes can be solids that have different structure crystals. Examples are allotropic modifications carbon C - diamond and graphite.

The number of known simple substances (approximately 400) is significantly greater than the number of chemical elements, since many elements can form two or more allotropic modifications.

Complex substances- These are substances that consist of atoms of different elements.

Examples of complex substances: HCl, H 2 O, NaCl, CO 2, H 2 SO 4, etc.

Complex substances are often called chemical compounds. In chemical compounds, the properties of the simple substances from which these compounds are formed are not preserved. The properties of a complex substance differ from the properties of the simple substances from which it is formed.

For example, chloride sodium NaCl can be formed from simple substances - sodium metal Na and chlorine gas Cl The physical and chemical properties of NaCl differ from the properties of Na and Cl 2.

In nature, as a rule, they are not found pure substances, but mixtures of substances. IN practical activities we also usually use mixtures of substances. Any mixture consists of two or more substances called mixture components.

For example, air is a mixture of several gaseous substances: oxygen O 2 (21% by volume), (78%), etc. Mixtures are solutions of many substances, alloys of some metals, etc.

Mixtures of substances are homogeneous (homogeneous) and heterogeneous (heterogeneous).

Homogeneous mixtures- these are mixtures in which there is no interface between the components.

Mixtures of gases (in particular, air) and liquid solutions (for example, a solution of sugar in water) are homogeneous.

Heterogeneous mixtures- These are mixtures in which the components are separated by an interface.

Heterogeneous include mixtures of solids (sand + chalk powder), mixtures of liquids insoluble in each other (water + oil), mixtures of liquids and solids insoluble in it (water + chalk).

The most important differences between mixtures and chemical compounds:

1. In mixtures, the properties of individual substances (components) are preserved.
2. The composition of mixtures is not constant.

Organic and inorganic substances;
> recognize metals and non-metals;
> identify metallic and non-metallic elements according to their location in periodic table D. I. Mendeleev; understand why all metals have similar properties.

Atoms under ordinary conditions cannot exist alone for long. They are able to combine with the same or other atoms, which causes a wide variety of substances in the world.

A substance formed by one chemical element is called simple, and a substance formed by several elements is called a complex or chemical compound.

Simple substances

Simple substances are divided into metals and non-metals. This classification of simple substances was proposed by the outstanding French scientist A.L. Lavoisier in late XVIII V. The chemical elements from which metals come are called metallic, and those that form non-metals are called
non-metallic. In the long version of D.I. Mendeleev’s system (endpaper II), they are delimited by a broken line. Metal elements are to the left of it; there are significantly more of them than non-metallic ones.

This is interesting

Simple substances of 13 elements - Au, Ag, Cu, Hg, Pb, Fe, Sn, Pt, S, C, Zn, Sb and As were known in ancient times.

Each of you can, without hesitation, name several metals (Fig. 36). They differ from other substances by a special “metallic” luster. These substances have a lot general properties.

Rice. 36. Metals

Metals under normal conditions are solids (only mercury is a liquid), conduct electricity and heat well, and have generally high temperature melting (over 500 °C).

Rice. 37. Simplified model internal structure metal

They are plastic; they can be forged and wire drawn from them.

Thanks to their properties, metals have confidently entered people's lives. About them of great importance the names indicate historical eras: copper age, Bronze 1st Age, Iron Age.

The similarity of metals is due to their internal structure.

Structure of metals. Metals are crystalline substances. Crystals in metals are much smaller than sugar crystals or table salt, and it is impossible to see them with the naked eye.

A molecule is an electrically neutral particle consisting of two or more connected atoms.

In each molecule, the atoms are connected to each other quite strongly, but the molecules to each other in the substance are very weakly connected. Therefore substances molecular structure have not high temperatures melting and boiling.

Oxygen and ozone are molecular substances. These are simple oxygen substances. An oxygen molecule contains two Oxygen atoms, and an ozone molecule contains three (Fig. 39).

Rice. 39. Models of molecules

Not only oxygen, but also many other elements form two or more simple substances. Therefore, there are several times more simple substances than chemical elements.

Names of simple substances.

Most simple substances are named after the corresponding elements. If the names are different, then they are given in the periodic table, with the name of the simple substance located below the name
element (Fig. 40).

Name the simple substances of the elements Hydrogen, Lithium, Magnesium, Nitrogen.

1 The term "molecule" comes from Latin word moles (mass), diminutive suffix cula and translated means “small mass”.

The names of simple substances are written inside the sentence with a small letter.

Rice. 40. Cell of the periodic table

Complex substances (chemical compounds)

The combination of atoms of different chemical elements gives rise to many complex substances(there are tens of thousands of times more of them than simple ones).

There are complex substances with molecular, atomic and ionic structure. Therefore, their properties are very different.

Molecular compounds are mostly volatile and often have an odor. Their melting and boiling points are significantly lower than those of compounds with an atomic or ionic structure.

The molecular substance is water. A water molecule consists of two Hydrogen atoms and one Oxygen atom (Fig. 41).

Rice. 41. Water molecule model

The molecular structure is carbon monoxide and carbon dioxide. gases, sugar, starch, alcohol, acetic acid etc. The number of atoms in the molecules of complex substances can be different - from two atoms to hundreds and even thousands.

Some compounds have an atomic structure.

One of them is the mineral quartz, the main component of sand. It contains Silicium and Oxygen atoms (Fig. 42).

Rice. 42. Connection model atomic structure(quartz)

There are also ionic compounds. These are table salt, chalk, soda, lime, gypsum and many others. Table salt crystals consist of positively charged Sodium ions and negatively charged Chlorine ions (Fig. 43). Each such ion is formed from the corresponding atom (§ 6).

Rice. 43. Model ionic compound(table salt)

This is interesting

In molecules organic compounds In addition to Carbon atoms, as a rule, there are also Hydrogen atoms, often Oxygen atoms, and sometimes some other elements.

The mutual attraction of many oppositely charged ions causes the existence of ionic compounds.

An ion formed from one atom is called simple, and an ion formed from several atoms is called complex.

Positively charged simple ions exist for metal elements, and negatively charged - for non-metallic elements.

Names of complex substances.

The textbook has so far provided technical or household names complex substances. In addition, substances also have chemical names. For example, chemical name table salt is sodium chloride, and chalk is calcium carbonate. Each such name consists of two words. The first word is the name of one of the elements that form the substance (it is written with a small letter), and the second comes from the name of another element.

Organic and inorganic substances.

Previously, organic substances were those substances that are found in living organisms. These are proteins, fats, sugar, starch, vitamins, compounds that give color, smell, taste to vegetables and fruits, etc. Over time, scientists began to obtain in laboratories substances similar in composition and properties that do not exist in nature. Nowadays, organic substances are called carbon compounds (with the exception of carbon dioxide and carbon dioxide, chalk, soda, and some others).

Most organic compounds are capable of burning, and when heated in the absence of air, they become charred (coal consists almost entirely of carbon atoms).

K not organic matter belong to the remaining complex substances, as well as all simple ones. They form the basis of the mineral world, i.e. they are found in soil, minerals, rocks, air, natural water. In addition, inorganic substances are also found in living organisms.

The material in this paragraph is summarized in Diagram 6.

Laboratory experiment No. 2

Introduction to different types of substances

You have been given the following substances (the option will be indicated by the teacher):

option I - sugar, calcium carbonate (chalk), graphite, copper;
option II - paraffin, aluminum, sulfur, sodium chloride (table salt).

The substances are in jars with labels.

Carefully examine the substances, pay attention to their names. Identify among them simple (metals, non-metals) and complex substances, as well as organic and inorganic.

Enter the name of each substance in the table and indicate its type by writing a “+” sign in the appropriate columns.

Conclusions

Substances can be simple and complex, organic and inorganic.

Simple substances are divided into metals and nonmetals, and chemical elements are divided into metallic and nonmetallic.

Metals have many common properties due to the similarity of their internal structure.

Nonmetals are made up of atoms or molecules and have different properties from metals.

Complex substances (chemical compounds) have an atomic, molecular or ionic structure.

Almost all Carbon compounds belong to organic substances, and the remaining compounds and simple substances belong to inorganic substances.

?
56. Which substance is called simple and which is called complex? What types of simple substances exist and what are the names of the corresponding elements?

57. According to what physical properties Can a metal be distinguished from a non-metal?

58. Define a molecule. How does a molecule of a simple substance differ from a molecule of a complex substance?
59. Fill in the blanks by inserting the words “Nitrogen” or “nitrogen” in the appropriate cases and explain your choice:
a) ... - the gas that contains the largest amount in the air;
b) a molecule... consists of two atoms...;
c) compounds... enter plants from the soil;
d)... is poorly soluble in water.

60. Fill in the blanks by inserting the words “element”, “atom” or “molecule” in the appropriate case and number:
A)... white phosphorus contains four... Phosphorus;
b) there is... carbon dioxide in the air;
c) gold is a simple substance... Aurum.

The main difference between them is their composition. Thus, simple substances include atoms of one element. Their (simple substances) crystals can be synthesized in the laboratory, and sometimes at home. However, it is often necessary to create certain conditions for storing the resulting crystals.

There are five classes into which simple substances are divided: metals, semimetals, nonmetals, intermetallic compounds, and halogens (not found in nature). They can be represented by atomic (Ar, He) or molecular (O2, H2, O3) gases.

As an example, we can take the simple substance oxygen. It includes molecules consisting of two atoms of the element Oxygen. Or, for example, the substance iron consists of crystals containing only atoms of the element Iron. Historically, it was customary to name a simple substance by the name of the element whose atoms are included in its composition. The structure of these compounds can be molecular or non-molecular.

Complex substances include atoms various types and upon decomposition can form two (or more) compounds. For example, when water splits, it forms oxygen and hydrogen. However, not every compound can be broken down into simple substances. For example, iron sulfide, formed by sulfur and iron atoms, cannot be broken down. In this case, in order to prove that the compound is complex and includes dissimilar atoms, the reverse reaction principle is used. In other words, iron sulfide is obtained using the starting components.

Elements are forms of chemical elements that exist in free form. Today science knows more than four hundred types of these elements.

Unlike complex substances, simple substances cannot be obtained from other simple substances. They also cannot be decomposed into other compounds.

All allotropic modifications have the property of transforming into each other. Different types simple substances formed by one chemical element can have different and different level chemical activity. For example, oxygen exhibits less activity than ozone, and the melting point of fullerene, for example, is lower than that of diamond.

IN normal conditions for eleven elements the simple substances will be gases (Ar, Xe, Rn, N, H, Ne, O, F, Kr, Cl, He,), for two liquids (Br, Hg), and for other elements - solids.

At temperatures close to room temperature, the five metals will take on a liquid or semi-liquid state. This is due to the fact that their melting point is almost equal. Thus, mercury and rubidium melt at 39 degrees, francium at 27, cesium at 28, and gallium at 30 degrees.

It should be noted that the concepts of “chemical element”, “atom”, “simple substance” should not be confused. So, for example, an atom has a certain specific meaning and it really exists. The definition of “chemical element” is generally abstract and collective. In nature, elements are present in the form of free or chemically bonded atoms. At the same time, the characteristics of simple substances (collections of particles) and chemical elements (isolated atoms) specific type) have their own characteristics.