What does simple matter mean. Simple and complex substances

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

Substance - everything that has a rest mass (i.e., it 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 a substance.

Matter exists in three states of aggregation - gaseous, liquid and solid. There is another state of matter - plasma (for example, there is plasma in thunderstorm and ball lightning), but the chemistry of plasma is almost not considered in the school course.

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

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

If a substance (for example, in air) contains two or more simple substances, and their atoms are not interconnected, then it is called not a complex, but a mixture of simple substances. The number of simple substances is relatively small (about five hundred), while 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 - reacts) with another simple substance - oxygen, resulting in the formation of a complex substance - carbon dioxide, in which carbon and oxygen atoms are bonded. 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 consists of) - turns into a simple substance - coal and a complex substance - water.

Chemistry is the study of the transformation of one substance into another. The task of chemistry is to find out with which substances this or that substance can interact (react) under given conditions, what is formed in this case. In addition, it is important to find out under what conditions this or that transformation can proceed and the desired substance can be obtained.

Physical properties of substances

Each substance is characterized by a combination 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. Physical methods can characterize the ability of a substance to conduct an electric current, determine the density of a substance, its hardness, etc. During physical processes, substances remain unchanged in composition.

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

Chemical properties of substances

The chemical properties of a substance are a set of information about what other substances and under what conditions a given substance enters into chemical interactions.. The most important task of chemistry is to identify the chemical properties of substances.

Chemical transformations involve the smallest particles of substances - atoms. During chemical transformations, other substances are formed from some substances, and the original substances disappear, and instead of them new substances (reaction products) are formed. A atoms at all 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 huge (and each of them has its own set of physical and chemical properties). Atoms, differing from each other in the 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 chemical elements found in nature. To date, physicists have learned how to create new types of atoms that are absent 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 a Latin name and a one- or two-letter symbol. There are no clear rules for the pronunciation of the symbols of chemical elements in the Russian-language chemical literature. Some pronounce it like this: they call the element in Russian (symbols of sodium, magnesium, etc.), others - in Latin letters (symbols of carbon, phosphorus, sulfur), others - how the name of the element sounds in Latin (iron, silver, gold, mercury ). It is customary to pronounce the symbol of the hydrogen element H in the same way as this letter is pronounced in French.

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

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 Chemical properties substances:

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

All are inorganic chemical compounds containing no 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 marked with 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 whole line complex connections. 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. Which character traits in 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. The carbon atoms form a zigzag chain, which is characteristic feature 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. As external conditions change, many chemical substances move from one aggregate state 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 natural form 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 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 various 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. good example this can be served by 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.

Based on the basic provisions of the atomic and molecular theory, it is possible to give definitions simple and complex matter.

simple substances Substances that are made up of atoms of one chemical element are called.

For example:

O 2 , N 2 , S 8 .

complex substancescalled substances consisting of atoms of various chemical elements.

For example:

H 2 O, H 2 SO 4, CuCl 2.

It should be noted that such a complex substance, such as, for example, water H 2 O, does not consist of hydrogen and oxygen (these are the names of simple substances - hydrogen - H 2 and oxygen - O 2), but of atoms of the element hydrogen - H and atoms of the element oxygen - O.

Some chemical elements are capable of forming several simple substances that differ from each other in structure and properties. Currently, more than 400 simple substances are known. So, the element carbon forms simple substances: graphite, diamond, carbyne and fullerene. During the combustion of each of these substances, only carbon monoxide (IV) CO 2 is formed. This confirms that these simple substances are composed of atoms of the same element. WITH carbon.

The phenomenon in which the same element can form several simple substances is called allotropy, and the resulting simple substances - allotropic modifications.

An example of allotropic modifications can be simple substances - oxygen ABOUT 2 and ozone ABOUT 3 , formed by atoms of the same element - oxygen.

The phenomenon of allotropy is caused by two reasons:

 a different number of atoms in a molecule, for example, oxygen O 2 and ozone O 3,

 different structure of the crystal lattice and the formation of various crystalline forms, for example, diamond, graphite, carbine and fullerene.

The ability of a substance to participate in certain chemical reactions characterizes Chemical properties substances.

Chemical phenomena (processes) – These are the processes by which other substances are formed from one substance.

If, as a result of the process, the chemical nature of the substance does not change, then such processes are considered physical.

Changes in the aggregate state of a substance are traditionally considered examples of physical processes: melting of ionic crystals of some salts, melting of metals, evaporation of water and other liquids, etc.

It should be noted that such a process as dissolution is considered physical and chemical, and, in this case, the boundaries between chemical and physical phenomena are rather arbitrary.

It is customary to distinguish clean ( chemically pure) substances and mixtures substances.

Pure or individual substances called substances consisting of particles of the same type (containing the same structural units).

Examples are silver (contains only silver atoms), sulfuric acid and carbon monoxide (IV) (contain only molecules of the corresponding substances).

Pure substances are characterized by the constancy of physical properties, for example, the melting point ( T pl) and boiling point ( T kip).

A substance is not pure if it contains any amount of one or more other substances - impurities.

If a system is formed by mixing several pure substances, and their properties have not changed, and it can be separated using physical methods into the original substances, then such a system is called mixture. The soil, sea ​​water, air are all examples of different mixtures. Substances in a mixture are called components. The content of the components in the mixture can vary within wide limits.

Many mixtures can be separated into constituent parts - components - based on the difference in their physical properties. Among the large number of methods used to separate and purify substances are:

 filtering,

 settling followed by decantation,

 separation using a separating funnel,

 centrifugation,

 Evaporation

 crystallization,

distillation (including fractional distillation),

 chromatography,

 sublimation and others.

It should be noted that in practice the substances called "pure" are such only conditionally. Purification of substances is a difficult task and it is practically impossible to obtain absolutely pure substances containing structural units of only one type.

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.

When studying the material of the previous paragraphs, you have already become acquainted with some substances. So, for example, a hydrogen gas molecule consists of two atoms of the chemical element hydrogen - H + H = H2.

Simple substances are substances that contain atoms of the same type.

Simple substances, from among the substances known to you, include: oxygen, graphite, sulfur, nitrogen, all metals: iron, copper, aluminum, gold, etc. Sulfur is made up of only atoms of the chemical element sulfur, while graphite is made up of atoms of the chemical element carbon.

It is necessary to clearly distinguish between concepts "chemical element" And "simple substance". For example, diamond and carbon are not the same thing. Carbon is a chemical element, and diamond is a simple substance formed by the chemical element carbon. In this case, a chemical element (carbon) and a simple substance (diamond) are called differently. Often a chemical element and a simple substance corresponding to it are called the same. For example, the element oxygen corresponds to a simple substance - oxygen.

Distinguish where in question about the element, and where about the substance, you need to learn! For example, when they say that oxygen is part of water, we are talking about the element oxygen. When they say that oxygen is a gas necessary for breathing, we are talking about a simple substance, oxygen.

Simple substances of chemical elements are divided into two groups - metals and non-metals.

Metals and non-metals radically different in their physical properties. All metals are solids under normal conditions, with the exception of mercury - the only liquid metal. Metals are opaque, have a characteristic metallic sheen. Metals are ductile and conduct heat and electricity well.

Non-metals are not similar to each other in physical properties. So, hydrogen, oxygen, nitrogen are gases, silicon, sulfur, phosphorus are solids. The only liquid non-metal, bromine, is a brown-red liquid.

If we draw a conditional line from the chemical element boron to the chemical element astatine, then in the long version of the Periodic System, non-metallic elements are located above the line, and below it - metal. In the short version of the Periodic Table, the non-metallic elements are located below this line, and both the metallic and non-metallic elements are above it. This means that it is more convenient to determine whether an element is metallic or non-metallic using the long version of the Periodic System. This division is conditional, since all elements in one way or another exhibit both metallic and non-metallic properties, but in most cases such a distribution is true.

Compound substances and their classification

If the composition of simple substances includes atoms of only one type, it is easy to guess that the composition of complex substances will include several types of different atoms, at least two. An example of a complex substance is water, you know its chemical formula - H2O. Water molecules are made up of two types of atoms: hydrogen and oxygen.

Complex Substances Substances that are made up of different types of atoms

Let's do the following experiment. Mix powders of sulfur and zinc. We place the mixture on a metal sheet and set it on fire with a wooden torch. The mixture ignites and quickly burns with a bright flame. After finishing chemical reaction a new substance was formed, which includes sulfur and zinc atoms. The properties of this substance are completely different than the properties of the original substances - sulfur and zinc.

Complex substances are usually divided into two groups: Not organic matter and their derivatives and organic substances and their derivatives. For example, rock salt is an inorganic substance, while the starch found in potatoes is an organic substance.

Structure types of substances

According to the type of particles that make up substances, substances are divided into substances molecular and non-molecular structure.

The composition of a substance can include various structural particles, such as atoms, molecules, ions. Therefore, there are three types of substances: substances of atomic, ionic and molecular structure. Substances of different types of structure will have different properties.

Substances of atomic structure

An example of substances atomic structure can be substances formed by the element carbon: graphite and diamond. The composition of these substances includes only carbon atoms, but the properties of these substances are very different. Graphite- fragile, easily exfoliating substance of gray-black color. Diamond- transparent, one of the hardest mineral on the planet. Why do substances composed of the same type of atoms have different properties? It's all about the structure of these substances. Carbon atoms in graphite and diamond bond in a different way. Substances of atomic structure have high boiling and melting points, as a rule, they are insoluble in water, non-volatile.

Crystal lattice - an auxiliary geometric image introduced to analyze the structure of a crystal

Substances of molecular structure

Substances of molecular structure- These are almost all liquids and most gaseous substances. There are also crystalline substances, the composition of the crystal lattice of which includes molecules. Water is a substance of molecular structure. Ice also has a molecular structure, but unlike liquid water, it has a crystal lattice, where all molecules are strictly ordered. Substances of a molecular structure have low boiling and melting points, are usually brittle, and do not conduct electric current.

Substances of ionic structure

Substances of ionic structure are solid crystalline substances. An example of an ionic compound substance is table salt. Its chemical formula is NaCl. As you can see, NaCl consists of ions Na+ and Cl⎺, alternating in certain places (nodes) of the crystal lattice. Substances of an ionic structure have high melting and boiling points, are brittle, as a rule, are highly soluble in water, and do not conduct electric current.

The concepts of "atom", "chemical element" and "simple substance" should not be confused.

• "Atom"- a concrete concept, since atoms really exist.
• "Chemical element" is a collective, abstract concept; in nature, a chemical element exists in the form of free or chemically bound atoms, that is, simple and complex substances.

The names of chemical elements and the corresponding simple substances coincide in most cases.

When we talk about a material or a component of a mixture - for example, a flask filled with gaseous chlorine, an aqueous solution of bromine, let's take a piece of phosphorus - we are talking about a simple substance. If we say that a chlorine atom contains 17 electrons, a substance contains phosphorus, a molecule consists of two bromine atoms, then we mean a chemical element.

It is necessary to distinguish between the properties (characteristics) of a simple substance (sets of particles) and the properties (characteristics) of a chemical element (an isolated atom of a certain type), see the table below:

Compounds must be distinguished from mixtures, which also consist of different elements.

The quantitative ratio of the components of the mixture can be variable, and the chemical compounds have a constant composition.

For example, in a glass of tea, you can add one spoonful of sugar, or several, and sucrose molecules С12Н22О11 contains exactly 12 carbon atoms, 22 hydrogen atoms and 11 oxygen atoms.

Thus, the composition of compounds can be described by one chemical formula, and the composition mixture is not.

The components of the mixture retain their physical and chemical properties. For example, if you mix iron powder with sulfur, then a mixture of two substances is formed. Both sulfur and iron in this mixture retain their properties: iron is attracted by a magnet, and sulfur is not wetted by water and floats on its surface.

If sulfur and iron react with each other, a new compound is formed with the formula FeS, which does not have the properties of either iron or sulfur, but has a set of its own properties. In conjunction FeS iron and sulfur are bound together and cannot be separated by methods that separate mixtures.

Thus, substances can be classified according to several parameters:

Conclusions from the article on the topic Simple and complex substances

• Simple substances- substances that contain atoms of the same type
• Elements are divided into metals and non-metals
• Complex Substances Substances that are made up of different types of atoms
• Compounds are divided into organic and inorganic
• There are substances of atomic, molecular and ionic structure, their properties are different
• Crystal cell is an auxiliary geometric image introduced to analyze the crystal structure