All substances that we talk about in the school chemistry course are usually divided into simple and complex. Simple substances are those substances whose molecules contain atoms of the same element. Atomic oxygen (O), molecular oxygen (O2) or simply oxygen, ozone (O3), graphite, diamond are examples of simple substances that form the chemical elements oxygen and carbon. Compounds are divided into organic and inorganic. Among inorganic substances, the following four classes are primarily distinguished: oxides (or oxides), acids (oxygenous and oxygen-free), bases (water-soluble bases are called alkalis) and salts. Compounds of non-metals (excluding oxygen and hydrogen) are not included in these four classes, we will call them conditionally "and other complex substances."

Simple substances are usually divided into metals, non-metals and inert gases. Metals include all chemical elements whose d- and f-sublevels are being filled, these are elements in the 4th period: Sc - Zn, in the 5th period: Y - Cd, in the 6th period: La - Hg, Ce - Lu, in the 7th period Ac - Th - Lr. If we now draw a line from Be to At among the remaining elements, then metals will be located to the left and below it, and non-metals to the right and top. Group 8 of the Periodic Table contains inert gases. Elements located on the diagonal: Al, Ge, Sb, Po (and some others. For example, Zn) in the free state have the properties of metals, and hydroxides have the properties of both bases and acids, i.e. are amphoteric hydroxides. Therefore, these elements can be considered metal-non-metals, occupying an intermediate position between metals and non-metals. Thus, the classification of chemical elements depends on what properties their hydroxides will have: basic - it means metal, acidic - non-metal, and both (depending on conditions) - metal-non-metal. The same chemical element in compounds with the lowest positive oxidation state (Mn + 2, Cr + 2) exhibits pronounced "metallic" properties, and in compounds with the maximum positive oxidation state (Mn + 7, Cr + 6) it exhibits the properties of a typical non-metal. To see the relationship of simple substances, oxides, hydroxides and salts, we present a summary table.

Everything that surrounds us has its own physical and chemical nature. What is called a substance and what types of it exist? It is a physical substance with a specific chemical composition. In Latin, the word "substance" is denoted by the term Substantia, which is also often used by scientists. What does it represent?

To date, more than 20 million different substances are known. There are all kinds of gases in the air, in the ocean, seas and rivers - water with minerals and salts. The solid surface layer of our planet consists of numerous rocks. A huge number of different substances are present in any living organism.

General concepts

In modern chemistry, a substance whose definition is understood as having a rest mass. It consists of elementary particles or quasiparticles. An integral feature of any substance is its mass. As a rule, at relatively low densities and temperatures, elementary particles such as electrons, neutrons, and protons are most often found in its composition. The latter two make up atomic nuclei. All these elementary particles form such substances as molecules and crystals. In essence, their atomic substance (atoms) consists of electrons, protons and neutrons.

From the point of view of biology, "substance" is the concept of matter that forms the tissues of any organisms. It is part of the organelles that are found in cells. In a general sense, "substance" is a form of matter from which all physical bodies are formed.

Matter properties

The properties of a substance are called a set of objective characteristics that determine individuality. They allow you to distinguish one substance from another. The most characteristic physical and chemical properties of a substance:

Density;

Boiling and melting points;

Thermodynamic characteristics;

Chemical properties;

Crystal structure values.

All listed parameters are non-changing constants. Since all substances are different from each other, they have certain characteristics. What is meant by this concept? The properties of a substance are its features, determined by measurement or observation, without transforming it into another substance. The most important of them are:

State of aggregation;

Color and luster;

The presence of an odor;

Insolubility or solubility in water;

melting and boiling point;

Density;

electrical conductivity;

Thermal conductivity;

Hardness;

fragility;

Plastic.

It is also characterized by such a physical property as shape. Color, taste, smell are determined visually and with the help of the senses. Physical parameters such as density, melting and boiling points, electrical conductivity are calculated using various measurements. Information about the physical properties of most substances is presented in special reference books. They depend on the aggregate state of the substance. So, the density of water, ice and steam is completely different. Oxygen is colorless in the gaseous state, but blue in the liquid state. Due to the differences in physical properties, many substances can be distinguished. So, copper is the only metal that has a reddish tint. It just tastes salty. In most cases, in order to define a substance, it is necessary to take into account several of its known properties.

Relationship of concepts

Many people confuse the concepts of "chemical element", "atom", "simple substance". In fact, they differ from each other. So, an atom is a concrete concept, since it really exists. Chemical element - abstract (collective) definition. In nature, it exists only in the form of bound or free atoms. In other words, it is a simple or complex substance. Each chemical element has its own symbol - a sign (symbol). In some cases, it also expresses the composition of a simple substance (B, C, Zn). But often this symbol denotes only a chemical element. This is clearly demonstrated by the formula of oxygen. So O is just a chemical element, and the simple substance oxygen is denoted by the formula O 2.

There are other differences between these concepts. It is necessary to distinguish between the characteristics (properties) of simple substances, which are a collection of particles, and a chemical element, which is an atom of a certain type. There are some differences in the names as well. Most often, the designation of a chemical element and a simple substance is the same. However, there are exceptions to this rule.

Substance classification

What is called a substance from the point of view of science? The number of different substances is very large. A natural substance, the definition of which is related to its natural origin, can be organic or inorganic. Man has learned to synthesize many compounds artificially. The definition of "substance" implies the division into simple (individual) substances and mixtures. The attitude to classification depends on how many of them are included in it.

The definition of a simple substance understands an abstract concept, which means a set of atoms interconnected according to certain physical and chemical laws. Despite this, the boundary between it and the mixture is very vague, since some substances have a variable composition. For them even the exact formula is not offered yet. Due to the fact that for a simple substance only its final purity is achievable, this concept remains an abstraction. In other words, in any of them there is a mixture of chemical elements in which one predominates. Often the purity of a substance directly affects its properties. In a general sense, a simple substance is built from the atoms of one chemical element. For example, an oxygen gas molecule contains 2 identical atoms (O 2).

What is a compound substance? Such a chemical compound includes various atoms that make up the molecule. It is sometimes referred to as a mixed chemical substance. Complex substances are mixtures whose molecules are formed from atoms of two or more elements. So, for example, in a water molecule there is one oxygen atom and 2 hydrogen (H 2 O). The concept of a complex substance corresponds to a molecule containing various chemical elements. There are many more such substances than simple ones. They can be natural and artificial.

Simple and the concept of which is to some extent conditional, differ in their properties. So, for example, titanium becomes strong only when it is freed from oxygen atoms to less than a hundredth of a percent. A complex and simple substance, the chemical definition of which is a bit difficult to understand, can be of two types: inorganic and organic.

inorganic substances

Inorganic are all chemical compounds that do not contain carbon. This group also includes some substances that contain this element (cyanides, carbonates, carbides, carbon oxides and several other substances). They do not have a skeleton characteristic of organic substances. Everyone can name a substance according to the formula thanks to the periodic system of Mendeleev and the school chemistry course. All of them are indicated by Latin letters. What is called the substance in this case? All inorganic substances are divided into the following groups:

Simple substances: metals (Mg, Na, Ca); non-metals (P, S); noble gases (He, Ar, Xe); amphoteric substances (Al, Zn, Fe);

Complex: salts, oxides, acids, hydroxides.

organic matter

The definition of organic matter is quite simple. These substances include chemical compounds that contain carbon. This class of substances is the most extensive. True, there are exceptions to this rule. So, organic substances do not include: carbon oxides, carbides, carbonates, carbonic acid, cyanides and thiocyanates.

The answer to the question "name includes a number of complex compounds. These include: amines, amides, ketones, anhydrides, aldehydes, nitriles, carboxylic acids, organosulfur compounds, hydrocarbons, alcohols, ethers and esters, amino acids.

The main classes of biological organic substances include lipids, proteins, nucleic acids, carbohydrates. They, in addition to carbon, have in their composition hydrogen, oxygen, phosphorus, sulfur, nitrogen. What are the characteristics of organic matter? Their diversity and diversity of structure is explained by the peculiarities of carbon atoms, which are able to form strong bonds when connected in chains. This results in very stable molecules. Carbon atoms form a zigzag chain, which is a characteristic feature of organic substances. In this case, the structure of molecules directly affects the chemical properties. Carbon in organic substances can be combined into open and cyclic (closed) chains.

Aggregate states

The definition of "substance" in chemistry does not give a detailed concept of its state of aggregation. They differ in the role that the interaction of molecules plays in their existence. There are 3 states of matter:

A solid in which the molecules are tightly connected. There is a strong attraction between them. In the solid state, the molecules of a substance are not able to move freely. They can only make oscillatory movements. Thanks to this, solids perfectly retain their shape and volume.

Liquid, in which the molecules are freer and can move from one place to another. Thanks to these properties, any liquid can take the form of a vessel and flow.

Gaseous, in which the elementary particles of matter move freely and randomly. Molecular bonds in this state are so weak that they can be far apart. In the gaseous state, the substance is able to fill large volumes.

Using water as an example, it is very easy to understand the difference between ice, liquid and vapor. All these states of aggregation do not belong to the individual characteristics of a chemical substance. They correspond only to the states of existence of a substance that depend on external physical conditions. That is why it is impossible to unambiguously attribute the attribute of liquid to water. When external conditions change, many chemicals pass from one state of aggregation to another. During this process, intermediate (boundary) types are discovered. The best known of these is the amorphous state, called glassy. Such a definition of "substance" in chemistry is associated with its structure (translated from Greek amorphos - shapeless).

In physics, one more state of aggregation, called plasma, is considered. It is fully or partially ionized and is characterized by the same density of negative and positive charges. In other words: plasma is electrically neutral. This state of matter occurs only at extremely high temperatures. Sometimes they reach thousands of kelvins. In some of its properties, plasma is the opposite of gas. The latter has low electrical conductivity. A gas is made up of particles that are similar to each other. However, they rarely meet. Plasma has a high electrical conductivity. It consists of elementary particles that differ in electric charge. They constantly interact with each other.

There are also such intermediate states of matter as a polymer (highly elastic). In connection with the presence of these transitional forms, specialists often use the concept of "phase" more broadly. Under certain conditions, quite different from the usual ones, some substances pass into special states, for example, superconducting and superfluid.

crystals

Crystals are solids that have the natural shape of regular polyhedra. It is based on their internal structure and depends on the arrangement of its constituent atoms, molecules and ions. In chemistry, it is called a crystal lattice. Such a structure is individual for each substance, therefore it is one of the main physicochemical parameters.

The distances between the particles that make up the crystals are called lattice parameters. They are determined using physical methods of structural analysis. It is not uncommon for solids to have more than one form of crystal lattice. Such structures are called polymorphic modifications. Among simple substances, rhombic and monoclinic forms are common. Such substances include graphite, diamond, sulfur, which are hexagonal and cubic modifications of carbon. This form is also noted in complex substances, such as quartz, cristobalite, tridymite, which are modifications of silicon dioxide.

Substance as a form of matter

Despite the fact that the concepts of "substance" and "matter" are very close in their meaning, they are not completely equivalent. This is claimed by many scientists. So, when mentioning the term "matter" most often they mean a rough, inert and dead reality, subject to the domination of mechanical laws. The definition of "substance" is more understood as a material that, due to its shape, evokes the idea of ​​life suitability and form.

Today, scientists consider matter to be an objective reality that exists in space and changes in time. It can be presented in two forms:

The first has a wave nature. It includes weightlessness, permeability, continuity. It can travel at the speed of light.

The second is corpuscular, having a rest mass. It consists of elementary particles that differ in their localization. It is hardly permeable or impenetrable and cannot propagate at the speed of light.

The first form of the existence of matter is called a field, and the second - substance. They have a lot in common, because even electrons have the properties of a particle and a wave. They appear at the level of the microcosm. That is why the division into field and substance is very convenient.

Unity of matter and field

Scientists have long established that the more massive and larger the elementary particle of matter, the sharper its individuality and delimitation is expressed. At the same time, the contrast between matter and the field, which is characterized by continuity, is more clearly visible. The smaller the elementary particles of a substance, the smaller its mass. In this case, contrasting it with the field becomes more difficult. In various microwaves, it generally loses its meaning, since different elementary particles are quanta excited by the states of different fields (electromagnetic - photons, nuclear - mesons).

The unity of matter and field and the absence of a clear boundary between them is expressed in the fact that under certain conditions particles arise due to the field, and in other cases - vice versa. An illustrative example of this is such a phenomenon as annihilation (the phenomenon of transformation of elementary particles). Any material body is a stable whole, possible due to the connection of its elements through fields.

Substances can be composed of atoms of the same or different chemical elements. On this basis, all substances are divided into simple and complex.

Substances consisting of atoms of one chemical element are called simple. Simple substances are divided into metals (formed by metal atoms: Na, K, Ca, Mg) and non-metals (formed by non-metal atoms H2, N2, O2, Cl2, F2, S, P, Si) according to their physical and chemical properties.

Substances consisting of atoms of different chemical elements are called complex substances. The main classes of complex inorganic substances include oxides, bases, acids and salts.

Oxides are binary compounds (compounds consisting of two chemical elements), which include the element oxygen in the oxidation state -2.
Oxides are divided into basic, amphoteric, acidic and non-salt-forming:
1. Basic oxides are formed by typical metal atoms and oxygen atoms. For example, Na2O, CaO, LiO. They correspond to hydroxides - bases.
2. Amphoteric oxides are formed by transition metal atoms and oxygen atoms. For example, BeO, ZnO, Al2O3. They correspond to amphoteric hydroxides.
3. Acid oxides are formed by non-metal atoms and oxygen atoms. For example, CO2, SiO2, N2O3, NO2, N2O5, P2O3, P2O5, SO2, SO3, Cl2O7, etc. They correspond to hydroxides - acids.
4. Non-salt-forming oxides are formed by non-metal atoms and oxygen. Non-salt-forming oxides include 4 oxides: CO, SiO, N2O, NO.

Bases are compounds that contain a metal (or ammonium) cation and one or more hydroxyl groups. For example, NaOH, Ca(OH)2, KOH, NH4OH.
Soluble bases, which are called alkalis, are especially distinguished. These include hydroxides of alkali and alkaline earth metals.
According to the number of hydroxyl groups, bases are divided into one-, two- and three-acid ones.

Amphoteric hydroxides are formed by beryllium, zinc or aluminum cations and hydroxide anions: Be(OH)2, Zn(OH)2, Al(OH)3.

Acids are compounds that contain hydrogen cations and anions of an acidic residue. According to the number of hydrogen cations, acids are divided into one-, two- and three-basic. According to the presence of oxygen in the acid residue, acids are divided into anoxic and oxygen-containing.
HF - hydrofluoric (or hydrofluoric) acid
HCl - hydrochloric (or hydrochloric) acid
HBr - hydrobromic acid
HI - hydroiodic acid
H2S - hydrosulphuric acid
HNO3 - nitric acid (corresponds to the acid oxide N2O5)
HNO2 - nitrous acid (corresponds to the acid oxide N2O3)
H2SO4 - sulfuric acid (corresponds to acid oxide SO3)
H2SO3 - sulfurous acid (corresponds to acid oxide SO2)
H2CO3 - carbonic acid (corresponds to the acidic oxide CO2)
H2SiO3 - silicic acid (corresponds to the acid oxide SiO2)
H3PO4 - phosphoric acid (corresponds to the acid oxide P2O5).

Salts are compounds that include a metal (or ammonium) cation and an anion of an acid residue.
According to the composition of the acid are divided into:
1. Medium - consist of a metal cation and an acid residue - this is the product of the complete replacement of acid hydrogen atoms with metal (or ammonium) cations. For example, Na2SO4, K3PO4.
Salts of hydrofluoric acid - fluorides,
salts of hydrochloric acid - chlorides,
salts of hydrobromic acid - bromides,
salts of hydroiodic acid - iodides,
salts of hydrosulphuric acid - sulfides,
salts of nitric acid - nitrates,
salts of nitrous acid - nitrites,
salts of sulfuric acid - sulfates,
salts of sulfurous acid - sulfites,
salts of carbonic acid - carbonates,
silicic acid salts - silicates,
salts of phosphoric acid - phosphates.
2. Acid salts - consist of a metal (or ammonium) cation, a hydrogen cation (s) and an anion of an acid residue - this is the product of incomplete replacement of acid hydrogen atoms by metal cations. Acidic salts can only form dibasic and tribasic acids. The prefix hydro- (or digdro) is added to the name of the salt. For example, NaHSO4 (sodium hydrogen sulfate), KH2PO4 (potassium dihydrogen phosphate).
3. Basic salts - consist of a metal (or ammonium) cation, hydroxydanion and an anion of an acid residue - this is the product of incomplete replacement of the hydroxyl groups of the base with acid residues. Basic salts can form only two- and three-acid bases. The prefix hydroxo- is added to the name of the salt. For example, (CuOH)2CO3 is copper (II) hydroxocarbonate.

The main difference between them is in their composition. So, 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 obtained crystals.

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

An example is the simple substance oxygen. It includes molecules consisting of two atoms of the element Oxygen. Or, for example, the substance iron consists of crystals, including only atoms of the element Iron. Historically, it is customary to call a simple substance by the name of the element, the atoms of which are part of it. The structure of these compounds can be molecular and non-molecular.

Compounds include atoms of various kinds and, when decomposed, can form two (or more) compounds. For example, water breaks down into oxygen and hydrogen. However, not every compound can be decomposed 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 principle of reverse reaction is applied. In other words, iron sulfide is obtained using the starting components.

Simple substances are forms of chemical elements that exist in a free form. Today, more than four hundred types of these elements are known to science.

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 passing into each other. Different types of simple substances formed by one chemical element can have different and different levels of chemical activity. So, for example, oxygen exhibits less activity than ozone, and the melting point of fullerene, for example, is lower than that of diamond.

Under normal conditions, for eleven elements, 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 - solid bodies.

At temperatures close to room temperature, the five metals will assume a liquid or semi-liquid state. This is due to the fact that their melting point is almost equal to So, 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 definite, concrete meaning and exists in reality. The definition of "chemical element" is generally abstract, collective. In nature, elements are present in the form of free or chemically bonded atoms. At the same time, the characteristics of simple substances (sets of particles) and chemical elements (isolated atoms of a particular type) have their own characteristics.

Organic and inorganic substances;
> recognize metals and non-metals;
> determine metallic and non-metallic elements by their location in the periodic system of D. I. Mendeleev; understand why all metals are similar in properties.

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

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. Such a classification of simple substances was proposed by the outstanding French scientist A.L. Lavoisier at the end of the 18th century. The chemical elements from which metals are derived 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 much more of them than non-metallic ones.

It is interesting

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

Each of you can, without hesitation, name several metals (Fig. 36). They differ from other substances in a special "metallic" luster. These substances have many properties in common.

Rice. 36. Metals

Under normal conditions, metals are solids (only mercury is a liquid), they conduct electric current and heat well, they have mostly high temperature melting (over 500 °C).

Rice. 37. Simplified model of the internal structure of the metal

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

Due to their properties, metals have confidently entered people's lives. Their great significance is evidenced by the names of historical epochs: the Copper Age, the Bronze Age, the Iron Age.

The similarity of metals is due to their internal structure.

The structure of metals. Metals are crystalline substances. Crystals in metals are much smaller than crystals of sugar or table salt and cannot be seen with the naked eye.

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

In each molecule, the atoms are interconnected quite firmly, and the molecules in the substance are very weakly connected to each other. Therefore, substances of a molecular structure have low melting and boiling points.

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 system, and the name of a simple substance is located below the name
element (Fig. 40).

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

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

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

Rice. 40. Cell of the periodic system

Complex substances (chemical compounds)

The combination of atoms of different chemical elements generates a set complex substances(there are tens of thousands of times more than simple ones).

There are complex substances with a 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 much lower than those of compounds with an atomic or ionic structure.

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

Rice. 41. Water molecule model

The molecular structure of 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 constituent of sand. It contains silicon and oxygen atoms (Fig. 42).

Rice. 42. Model of the connection of the atomic structure (quartz)

There are also ionic compounds. These are table salt, chalk, soda, lime, gypsum and many others. 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 of an ionic compound (common salt)

It is interesting

The molecules of organic compounds, in addition to carbon atoms, usually contain hydrogen atoms, often oxygen atoms, and sometimes some other elements.

The mutual attraction of many oppositely charged ions determines 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 metallic elements, while negatively charged simple ions exist for non-metallic elements.

Names of complex substances.

The textbook has so far given the technical or everyday names of complex substances. In addition, substances have chemical names. For example, the chemical name of 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 called those substances that are contained 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 substances in laboratories similar in composition and properties that do not exist in nature. Now carbon compounds are called organic substances (with the exception of carbon monoxide and carbon dioxide, chalk, soda, and some others).

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

Other complex substances, as well as all simple ones, belong to inorganic substances. They form the basis of the mineral world, that is, they are contained in soil, minerals, rocks, air, natural water. In addition, inorganic substances are also found in living organisms.

The material of the paragraph is summarized in Scheme 6.

Laboratory experiment No. 2

Familiarization with substances of various types

You have been given the following substances (the teacher will indicate the option):

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

Substances are in jars with labels.

Carefully consider 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.

findings

Substances are simple and complex, organic and inorganic.

Simple substances are divided into metals and non-metals, and chemical elements - into metallic and non-metallic.

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

Non-metals are composed of atoms or molecules and differ in their properties from metals.

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

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

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

57. By what physical properties can a metal be distinguished from a non-metal?

58. Define a molecule. What is the difference between a molecule of a simple substance and a molecule of a complex substance?
59. Fill in the gaps by inserting the words "Nitrogen" or "nitrogen" in the appropriate cases and explain your choice:
a) ... - gas, which contains the largest amount in the air;
b) a molecule ... consists of two atoms ...;
c) compounds ... enter plants from the soil;
d) ... poorly soluble in water.

60. Fill in the gaps 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.