All substances that we talk about in a 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. Complex substances are divided into organic and inorganic. Among inorganic substances, the following four classes are primarily distinguished: oxides (or oxides), acids (oxygen 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 conventionally “and other complex substances”.
Simple substances are usually divided into metals, non-metals and inert gases. Metals include all chemical elements in which the d- and f-sublevels are being filled, these are the 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 to the left and below there will be metals, and to the right and above - non-metals. Inert gases are located in group 8 of the Periodic Table. Elements located on the diagonal: Al, Ge, Sb, Po (and some others. For example, Zn) in a 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 - which means it is a metal, acidic - a non-metal, and both (depending on the conditions) - metal-non-metal. The same chemical element in compounds with a lower positive degree oxidation (Mn+2, Cr+2) exhibits pronounced “metallic” properties, and in compounds with a maximum positive oxidation state (Mn+7, Cr+6) exhibits the properties of a typical non-metal. To see the relationship simple substances, oxides, hydroxides and salts, we present a summary table.
Under chemical element understand a collection of atoms with the same positive charge kernels and with a certain set of properties. Atoms of the same chemical element combine to form simple substance. When atoms of different chemical elements combine, complex substances (chemical compounds) or mixtures. The difference between chemical compounds and mixtures is that:
They have new properties that the simple substances from which they were obtained did not have;
They cannot be mechanically divided into their component parts;
Chemical elements in their composition can only be in strictly defined quantitative ratios.
Some chemical elements (carbon, oxygen, phosphorus, sulfur) can exist in the form of several simple substances. This phenomenon is called allotropy, and varieties of simple substances of the same chemical element are called its allotropic modifications(modifications).
Tasks
1.1. What more exists in nature: chemical elements or simple substances? Why?
1.2. Is it true that sulfur and iron are included in the composition of iron sulfide as substances? If not, what is the correct answer?
1.3. Name allotropic modifications of oxygen. Do they differ in their properties? If so, how?
1.4. Which of the allotropic modifications of oxygen is chemically more active and why?
1.5. The simple substances or chemical elements are zinc, sulfur and oxygen in the following reactions:
1) CuSO 4 + Zn = ZnSO 4 + Cu;
2) S + O 2 = SO 2;
3) Zn + 2HC1 = ZnCl 2 + H 2 ;
4) Zn + S = ZnS;
5) 2H 2 0 = 2H 2 + O 2 .
1.6. Is it possible to get another simple substance from one simple substance? Give a reasoned answer.
1.7. When a substance is burned in oxygen, sulfur (IV) oxide, nitrogen and water are produced. What chemical elements form the starting substance?
1.8. Indicate whether simple or complex substances include: H 2 O, C1 2, NaOH, O 2, HNO 3, Fe, S, ZnSO 4, N 2, AgCl, I 2, A1 2 O 3, O 3?
1.9. For which chemical elements are allotropic modifications known? Name these modifications.
1.10. Is it possible for a chemical element to transition from one allotropic modification to another? Give examples.
1.11. What chemical elements do they mean when they talk about diamond and ozone?
1.12. Which of the substances are chemical compounds and which are mixtures:
2) air;
4) sulfuric acid;
1.13. How to prove that sodium chloride is a complex substance?
1.14. Name three allotropic modifications of carbon.
1.15. What are allotropic modifications of phosphorus called and how do they differ from each other?
1.16. What are allotropic modifications of sulfur called and how do they differ from each other?
1.17. Indicate which of the statements is true and why - the composition of barium sulfate includes:
1) simple substances barium, sulfur, oxygen;
2) chemical elements barium, sulfur, oxygen.
1.18. How many liters of ammonia can be produced from a mixture of 10 liters of nitrogen and 30 liters of hydrogen?
1.19. How many liters of water vapor are produced from a mixture of 10 liters of hydrogen and 4 liters of oxygen? What gas and in what volume will remain in excess?
1.20. How many grams of zinc sulfide (ZnS) can be formed from a mixture of 130 g of zinc and 48 g of sulfur?
1.22. What is a solution of alcohol in water - a mixture or a chemical compound?
1.23. Can a complex substance consist of atoms of the same type?
1.24. Which of the following substances are mixtures and which are chemical compounds:
1) bronze;
2) nichrome;
3) kerosene;
4) potassium nitrate:
5) rosin;
6) superphosphate.
1.25. Given a mixture of Cl 2 + HCl + CaCl 2 + H 2 O.
1) How much is in the mixture various substances;
2) How many chlorine molecules are in the mixture;
3) How many chlorine atoms are in the mixture;
4) How many molecules of different substances are contained in the mixture.
When studying the material in the previous paragraphs, you have already become acquainted with some substances. For example, a molecule of hydrogen gas 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 known to you include: oxygen, graphite, sulfur, nitrogen, all metals: iron, copper, aluminum, gold, etc. Sulfur consists only of atoms of the chemical element sulfur, while graphite consists of atoms of the chemical element carbon.
It is necessary to clearly distinguish between concepts "chemical element" And "simple matter". 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, the chemical element (carbon) and the simple substance (diamond) are called differently. Often a chemical element and its corresponding simple substance are named the same. For example, the element oxygen corresponds to a simple substance - oxygen.
It is necessary to learn how to distinguish between where we are talking about an element and where about a substance! 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 the 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 at normal conditions solids, with the exception of mercury - the only liquid metal. Metals are opaque and have a characteristic metallic luster. Metals are ductile and conduct heat and electricity well.
Nonmetals 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 is bromine, a brownish-red liquid.
If you draw a conventional line from the chemical element boron to the chemical element astatine, then in the long version of the Periodic System there are non-metallic elements above the line, and below it - metal. IN short version The Periodic Table contains non-metallic elements below this line, and both metallic and non-metallic elements 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 Table. This division is arbitrary, since all elements in one way or another exhibit both metallic and non-metallic properties, but in most cases this distribution corresponds to reality.
Complex 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 containing atoms of various types
Let's conduct the following experiment. Mix sulfur and zinc powders. Place the mixture on a metal sheet and set it on fire using a wooden torch. The mixture ignites and quickly burns with a bright flame. After the completion of the chemical reaction, a new substance was formed, which included sulfur and zinc atoms. The properties of this substance are completely different from the properties of the starting substances - sulfur and zinc.
Complex substances are usually divided into two groups: inorganic substances and their derivatives and organic substances and their derivatives. For example, rock salt is an inorganic substance, and the starch contained in potatoes is an organic substance.
Types of structure of substances
Based on the type of particles that make up the substances, substances are divided into substances molecular and non-molecular structure.
The substance may contain various structural particles, such as atoms, molecules, ions. Consequently, there are three types of substances: substances of atomic, ionic and molecular structure. Substances various types buildings will have various properties.
Substances of atomic structure
An example of substances of atomic structure are substances formed by the element carbon: graphite and diamond. These substances contain only carbon atoms, but the properties of these substances are very different. Graphite– a fragile, easily exfoliating substance of gray-black color. Diamond– transparent, one of the hardest minerals on the planet. Why do substances consisting of the same type of atom have different properties? It's all about the structure of these substances. Carbon atoms in graphite and diamond combine in different ways. Substances of atomic structure have high temperatures boiling and melting, as a rule, 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 whose crystal lattice includes molecules. Water is a substance of molecular structure. Ice also has a molecular structure, but unlike liquid water, has a crystal lattice where all molecules are strictly ordered. Substances of molecular structure have low boiling and melting points, are usually fragile, and do not conduct electricity.
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 we can see, NaCl consists of ions Na+ and Cl⎺, alternating in certain places (nodes) of the crystal lattice. Substances with an ionic structure have high melting and boiling points, are fragile, are usually 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 specific concept, since atoms really exist.
- « Chemical element» – this is a collective, abstract concept; In nature, a chemical element exists in the form of free or chemically bonded atoms, that is, simple and complex substances.
The names of chemical elements and the corresponding simple substances are the same in most cases.
When we talk about a material or component of a mixture - for example, a flask is filled with chlorine gas, 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, the substance contains phosphorus, the 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 (a collection of particles) and the properties (characteristics) of a chemical element (an isolated atom of a certain type), see the table below:
Complex substances must be distinguished from mixtures, which also consist of different elements.
The quantitative ratio of the components of the mixture can be variable, but the chemical compounds have a constant composition.
For example, in a glass of tea you can add one spoon 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 no mixture.
The components of the mixture retain their physical and chemical properties. For example, if you mix iron powder with sulfur, 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 connection FeS iron and sulfur are bound to each other, and it is impossible to separate them using the methods used to separate mixtures.
Thus, substances can be classified according to several parameters:
Conclusions from an article on the topic Simple and complex substances
- Simple substances- substances that contain atoms of the same type
- Simple substances are divided into metals and non-metals
- Complex substances- substances containing atoms of various types
- Complex substances are divided into organic and inorganic
- There are substances of atomic, molecular and ionic structure, their properties are different
- Crystal lattice– an auxiliary geometric image introduced to analyze the crystal structure
Organic and inorganic substances;
> recognize metals and non-metals;
> identify metallic and non-metallic elements by their location in periodic table D. I. Mendeleev; understand why all metals have similar properties.
Atoms in normal 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 at the end of the 18th century. 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 many common 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 of historical eras indicate: the Copper Age, the Bronze Age, the Iron Age.
The similarity of metals is due to their internal structure.
Structure of metals. Metals are crystalline substances. The crystals in metals are much smaller than sugar or table salt crystals and cannot be seen with the naked eye.
Molecule - 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 of 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 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 the Latin word moles (mass), the 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 structures. 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 vary - 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. Model of compound of 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 of an 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 given technical or everyday names for complex substances. In addition, substances also 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 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).
Other complex substances, as well as all simple ones, belong to inorganic substances. 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 non-metals, and chemical elements are divided into metallic and non-metallic.
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. By 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.
Ticket 1:
Chemistry is the science of substances, their structure and properties, as well as the transformation of some substances into others. A chemical element is a certain type of atom with the same positive nuclear charge. A chemical element exists in three forms: 1) a single atom; 2) simple substances; 3) complex substances or chemical compounds. Substances formed by one chemical element are called simple. Substances formed by several chemical elements are called complex
Ticket 2:
Human life depends on chemistry - the processes of breaking down food in the body are continuous chemical reaction. Well, everything we wear, what we drive in, what we look at, one way or another, goes through certain stages of chemical processing - be it painting, making various alloys, etc. Chemistry plays a big role in industry. Both heavy and light. For example: without chemistry, a person would not be able to obtain medicines and some food products non-natural origin (vinegar). By and large - chemistry within and around us. The chemical industry is one of the most rapidly developing industries. It refers to the industries that form the basis of modern scientific and technological progress (plastics, chemical fibers, dyes, pharmaceuticals, detergents and cosmetics). As a result economic activity person changes gas composition and dustiness lower layers atmosphere. As a result, this can cause a long-term effect on a person: chronic inflammatory diseases various organs, changes nervous system, an effect on the intrauterine development of the fetus, leading to various abnormalities in newborns. Environmental problems can only be solved by stabilizing the economic situation and creating an economic mechanism for environmental management in which payment for pollution environment will correspond to the cost of its complete cleaning.
Ticket 3:
The most famous:
Dmitry Ivanovich Mendeleev, of course, with his famous periodic system of chemical elements.
KUCHEROV MIKHAIL GRIGORIEVICH - Russian organic chemist, discovered the reaction of catalytic hydration of acetylene hydrocarbons with the formation of carbonyl-containing compounds, in particular, the conversion of acetylene into acetaldehyde in the presence of mercury salts.
KONOVALOV MIKHAIL IVANOVICH - Russian organic chemist, discovered the nitrating effect of a weak solution of nitric acid on limiting hydrocarbons, developed methods for the isolation and purification of naphthenes.
SERGEY VASILIEVICH LEBEDEV - Russian chemist, first obtained a sample of synthetic butadiene rubber, obtained synthetic rubber by polymerizing butadiene under the action of metallic sodium. Thanks to Lebedev, since 1932, a domestic synthetic rubber industry began to be created in our country.
Ticket 4: Type of element, what element, information about it (number of electron layers, number of electrons on the external level, degree of deposition, number of protons/neutrons/electrons, relative mass, element group, configuration of the outer layer), reaction - interaction of elements, substances, formulas - substances and classes of substances.
Ticket 5: An atom consists of an atomic nucleus and particles (electrons, protons, neutrons) located on the periphery. Protons and neutrons make up the nucleus of an atom, which carries almost all the mass of the atom. Electrons make up the electronic shell of the atom, which is divided into energy levels (1,2,3, etc.), the levels are divided into sublevels (denoted by the letters s, p, d, f). The sublevels consist of atomic orbitals, i.e. regions of space where electrons are likely to reside. Orbitals are designated as 1s (orbital of the first level, s-sublevel) The filling of atomic orbitals occurs in accordance with three conditions: 1) The principle of minimum energy
2) The exclusion rule, or the Pauli principle
3) The principle of maximum multiplicity, Hund's rule.
Isotopes are atoms of the same element that differ in the number of neutrons in the nucleus.
For example, the most striking example can be hydrogen isotopes:
1H - protium with one proton in the nucleus and 1 electron in the shell
2H - deuterium with one proton and one neutron in the nucleus and one electron in the shell
3H - tritium with one proton and two neutrons in the nucleus and one electron in the shell
Ticket 6:
1. H)1
2. He)2
3. Li)2)1
4. Be)2)2
5. B)2)3
6. C)2)2
7. N)2)5
8. O)2)6
9. F)2)7
10. Ne)2)8
11. Na)2)8)1
12. Mg)2)8)2
13. Al)2)8)3
14. Si)2)8)4
15. P)2)8)5
16. S)2)8)6
17. Cl)2)8)7
18. Ar)2)8)8
19. K)2)8)8)1
20. Ca)2)8)8)8
At the external level, if there are 2 or 8 electrons, it is complete, and if there is a different number, it is not complete.
Ticket 8:
An ionic bond is: a typical metal + a typical non-metal. Example: NaCl, AlBr3. Covalent polar is: nonmetal + nonmetal (different). Example: H2O, HCl. Covalent nonpolar is: nonmetal + nonmetal (identical). Example: H2, Cl2, O2, O3. And metallic when metal + metal Li, Na, K
Ticket 11:
Complex substances consist of organic and inorganic substances.
Inorganic substances: Oxides, hydroxides, salts
Organic matter: acids, bases.
Well, my friend, I helped with whatever I could.)
