Work program for an optional course in chemistry in grade 10 “Fundamentals of Organic Chemistry”

Chemistry tutorial › Organic chemistry

It is known that all complex substances can be divided into organic and inorganic.

The composition of inorganic substances can include any element of the periodic table. The main classes of inorganic substances are oxides, acids, bases and salts. The properties of these substances were discussed in the first two sections.

The composition of organic substances necessarily includes a carbon atom, which forms chains in the vast majority of organic compounds. These chains have different lengths and different structures, so theoretically there can be an infinite number of organic compounds.

The basis of any organic compound is a hydrocarbon chain, which can be combined with functional groups.

The properties of an organic compound are described according to the scheme:

• definition;
• homologous series;
• isomerism;
• nomenclature (names);
• molecular structure (hydrocarbon chain and functional groups);
• properties associated with the structure of the functional group;
• hydrocarbon radical;

After reading the next lesson, try to describe the compounds you are studying using any example using this diagram. And everything will work out!

Subject of organic chemistry. Theory of the structure of organic substances

Organic substances have been known to people for a long time. Even in ancient times, people used sugar, animal and vegetable fats, dyes and aromatic substances. All these substances were isolated from living organisms. Therefore, such compounds began to be called organic, and the branch of chemistry that studied substances formed as a result of the vital activity of living organisms was called “organic chemistry.” This definition was given by the Swedish scientist Berzelius* in 1827.

* Berzelius Jens Jacob (08/20/1779–08/7/1848) - Swedish chemist. He tested and proved a number of basic laws of chemistry, determined the atomic masses of 45 chemical elements, introduced the modern designation of chemical elements (1814) and the first chemical formulas, developed the concepts of “isomerism”, “catalysis” and “allotropy”.

Already the first researchers of organic substances noted the features of these compounds. Firstly, when burned, they all form carbon dioxide and water, which means they all contain carbon and hydrogen atoms. Secondly, these compounds had a more complex structure than mineral (inorganic) substances. Thirdly, serious difficulties arose regarding the methods for obtaining and purifying these compounds. It was even believed that organic compounds could not be obtained without the participation of the “vital force”, which is inherent only in living organisms, that is, organic compounds could not, it seemed, be obtained artificially.

And finally, compounds of the same molecular composition, but different in properties, were discovered. This phenomenon was not typical for inorganic substances. If the composition of an inorganic substance is known, then its properties are also known.

Question. What properties do H2SO4 have? Ca(OH)2?

And organic chemists have discovered that a substance with the composition C2H6O is considered by some researchers to be a fairly inert gas, while by others it is a liquid that actively participates in various reactions. How to explain this?

By the middle of the 19th century, many theories had been created, the authors of which tried to explain these and other features of organic compounds. One of these theories was Butlerov’s theory of chemical structure*.

* Butlerov Alexander Mikhailovich (09/15/1928–08/17/1886) - Russian chemist. He created the theory of the chemical structure of organic substances, which lies at the basis of modern chemistry. He predicted the isomerism of many organic compounds and laid the foundations for the doctrine of tautomerism.

Some of its provisions were outlined by A. M. Butlerov in 1861 at a conference in Speyer, others were formulated later in the scientific works of A. M. Butlerov. In general, the main provisions of this theory in its modern presentation can be formulated as follows.

1. Atoms in molecules are arranged in a strict order according to their valence.

2. The carbon atom in organic molecules always has a valence of four .

3. The order of connections of atoms in a molecule and the nature of the chemical bonds between atoms is called chemical structure.

4. The properties of organic compounds depend not only on which atoms and in what quantities are included in the molecule, but also on the chemical structure:

• substances of different structures have different properties;
• substances of similar structure have similar properties.

5. By studying the properties of organic compounds, one can draw a conclusion about the structure of a given substance and describe this structure with a single chemical formula.

6. The atoms in a molecule influence each other, and this influence affects the properties of the substance.

When studying organic chemistry, you need to remember these provisions more often and, before describing the properties of any substance, you should indicate its structure using a chemical formula, which will show the order of connection of atoms in the molecule - a graphic formula.

Abstract Subject of organic chemistry

Organic chemistry The concept of organic chemistry and the reasons for its isolation into an independent discipline

Organic chemistry is the chemistry of hydrocarbons and their derivatives, i.e., products formed when hydrogen in the molecules of these substances is replaced by other atoms or groups of atoms.

Signs of organic substances:

1. Contain carbon in valency 4
2. Burns or decomposes to form carbon-containing products
3. The bonds in the molecule are usually covalent

Reasons for separating organic chemistry into an independent discipline:

1. Variety of organic compounds
2. Numerous organic compounds
3. Specific structure and properties of organic compounds
4. Great practical importance of carbon compounds: oil and methods of its processing

Reasons for the diversity of organic compounds:

1. Connection of carbon atoms in chains of different lengths
2. Different nature of carbon chains: straight, branched cyclic
3. The ability of a carbon atom to form single and multiple bonds with each other and other atoms
4. Many elements that make up organic compounds
5. Isomerism

Isomers are substances of the same qualitative and quantitative composition (i.e., having the same total formula), but different structures, therefore, different physical and chemical properties.

Phenanthrene (right) and anthracene (left) are structural isomers.

Brief outline of the development of organic chemistry

The first period of the development of organic chemistry, called empirical (from the mid-17th to the end of the 18th century), covers a large period of time from man’s initial acquaintance with organic substances to the emergence of organic chemistry as a science. During this period, knowledge of organic substances, methods of their isolation and processing occurred experimentally. According to the definition of the famous Swedish chemist I. Berzelius, organic chemistry of this period was “the chemistry of plant and animal substances.” By the end of the empirical period, many organic compounds were known. Citric, oxalic, malic, gallic, and lactic acids were isolated from plants, urea was isolated from human urine, and hippuric acid was isolated from horse urine. The abundance of organic substances served as an incentive for an in-depth study of their composition and properties. The next period, analytical (late 18th – mid-19th centuries), is associated with the emergence of methods for determining the composition of organic substances. The most important role in this was played by the law of conservation of mass discovered by M.V. Lomonosov and A. Lavoisier (1748), which formed the basis of quantitative methods of chemical analysis. It was during this period that it was discovered that all organic compounds contain carbon. In addition to carbon, elements such as hydrogen, nitrogen, sulfur, oxygen, and phosphorus, which are currently called organogenic elements, were found in organic compounds. It became clear that organic compounds differ from inorganic ones primarily in composition. At that time, there was a special attitude towards organic compounds: they continued to be considered products of the vital activity of plant or animal organisms, which can only be obtained with the participation of an intangible “vital force”. These idealistic views were refuted by practice. In 1828, the German chemist F. Wöhler synthesized the organic compound urea from inorganic ammonium cyanate. From the moment of F. Wöhler's historical experience, the rapid development of organic synthesis began. I. N. Zinin obtained aniline by reducing nitrobenzene, thereby laying the foundation for the aniline dye industry (1842). A. Kolbe synthesized acetic acid (1845). M, Berthelot – substances like fats (1854). A. M. Butlerov - the first sugary substance (1861). Nowadays, organic synthesis forms the basis of many industries. The structural period of great importance in the history of organic chemistry. The basic principles of the theory of structure were of great importance not only for their time, but also serve as a scientific platform for modern organic chemistry. At the beginning of the 20th century, organic chemistry entered the modern period of development. Currently, in organic chemistry, quantum mechanical concepts are used to explain a number of complex phenomena; chemical experiment is increasingly combined with the use of physical methods; The role of various calculation methods has increased. Organic chemistry has become such a vast field of knowledge that new disciplines are being separated from it - bioorganic chemistry, chemistry of organoelement compounds, etc.

Theory of the chemical structure of organic compounds by A. M. Butlerov

The decisive role in creating the theory of the structure of organic compounds belongs to the great Russian scientist Alexander Mikhailovich Butlerov. On September 19, 1861, at the 36th Congress of German Naturalists, A.M. Butlerov published it in his report “On the Chemical Structure of Matter.”

Basic provisions of the theory of chemical structure of A.M. Butlerov:

1. All atoms in a molecule of an organic compound are bonded to each other in a specific sequence according to their valence. Changing the sequence of atoms leads to the formation of a new substance with new properties. For example, the composition of the substance C2H6O corresponds to two different compounds: dimethyl ether (CH3-O-CH3) and ethyl alcohol (C2H5OH) - see Isomerism.
2. The properties of substances depend on their chemical structure. Chemical structure is a certain order in the alternation of atoms in a molecule, in the interaction and mutual influence of atoms on each other - both neighboring and through other atoms. As a result, each substance has its own special physical and chemical properties. For example, dimethyl ether is an odorless gas, insoluble in water, mp. = -138°C, t°boil. = 23.6°C; ethyl alcohol – a liquid with an odor, soluble in water, mp. = -114.5°C, t°boil. = 78.3°C. This position of the theory of the structure of organic substances explained the phenomenon of isomerism, which is widespread in organic chemistry. The given pair of compounds - dimethyl ether and ethyl alcohol - is one of the examples illustrating the phenomenon of isomerism.
3. The study of the properties of substances allows us to determine their chemical structure, and the chemical structure of substances determines their physical and chemical properties.
4. Carbon atoms are able to connect with each other, forming carbon chains of various types. They can be both open and closed (cyclic), both direct and branched. Depending on the number of bonds the carbon atoms spend connecting to each other, the chains can be saturated (with single bonds) or unsaturated (with double and triple bonds).
5. Each organic compound has one specific structural formula or structural formula, which is built based on the provision of tetravalent carbon and the ability of its atoms to form chains and cycles. The structure of a molecule as a real object can be studied experimentally using chemical and physical methods.

A.M. Butlerov did not limit himself to theoretical explanations of his theory of the structure of organic compounds. He conducted a series of experiments, confirming the predictions of the theory by obtaining isobutane, tert. butyl alcohol, etc. This made it possible for A.M. Butlerov to declare in 1864 that the available facts allow us to vouch for the possibility of synthetically producing any organic substance.

Features of the structure of organic compounds

Organic chemistry studies the structure of molecules and properties of carbon compounds, except for the simplest (carbonic and hydrocyanic acids and their salts).

The composition of inorganic compounds can include any of the 114 currently known chemical elements. More than 0.5 million inorganic substances are now known.

Organic molecules usually contain atoms of 6 chemical elements: C, H, O, N, P, S. And yet, more than 20 million organic compounds are currently known.

Why are there so many organic substances?

Since any organic compound contains a carbon atom, let’s try to find the answer to this question by considering the structural features of the carbon atom.

Carbon is a chemical element of the 2nd period, group IV of Mendeleev’s Periodic Table of Chemical Elements, therefore, the structure of its atom can be depicted as follows:

Thus, there are four electrons in the outer level of the carbon atom. Being a non-metal, a carbon atom can both give away four electrons and also accept four electrons until the completion of the outer level. That's why:

• The carbon atom in organic compounds is always tetravalent ;
• carbon atoms are able to connect with each other, forming chains of various lengths and structures;
• carbon atoms are connected to each other and to other atoms using a covalent bond, which is indicated by a dash in the formula; since the valence of a carbon atom is four, the total number of lines (chemical bonds) of one carbon atom is also four.

Carbon chains can contain different numbers of carbon atoms: from one to several thousand. In addition, the chains can have different structures:

Different types of chemical bonds can occur between carbon atoms:

Therefore, just four (!) carbon atoms can form more than 10 compounds of different structures, even if such compounds contain only carbon and hydrogen atoms. These compounds will have, for example, the following "carbon skeletons":

and others.

Task 17.1. Try to make 2-3 chains of carbon atoms of a different structure from four carbon atoms yourself.

conclusions

The ability of carbon atoms to form CARBON CHAINS of different composition and structure is the main reason for the diversity of organic compounds.

Subject of organic chemistry. Chemistry. Grade 10. Lesson summary

UMK "Chemistry. 10th grade” by O. S. Gabrielyan.

Purpose of the lesson: To introduce students to the concept of organic chemistry, the history of the development of organic chemistry, the types of organic substances, their diversity and the reasons for such diversity. Identify the distinctive features of organic substances from inorganic ones.

Tasks:

• educational: know the concepts of organic substances, their composition, structural features, reasons for diversity.
• developing: learning to independently find information, compare, draw conclusions, develop cognitive interest in the subject.
• educational: to cultivate a caring attitude towards nature, the ability to listen.

Lesson type: Learning new material using DOC.

Forms of student work: individual, collective.

Necessary technical equipment: computer, multimedia equipment, Internet.

Table 1. Lesson structure and flow

Table 2. List of electronic educational resources used in this lesson

Classification of organic compounds

Since there are so many organic compounds, they are classified according to different criteria:

• according to the structure of the carbon chain - linear, branched, cyclic compounds;
• by type of chemical bond - saturated, unsaturated and aromatic compounds;
• by composition - hydrocarbons, oxygen-containing compounds, nitrogen-containing compounds and others.

This tutorial will examine the properties of compounds of various classes, so definitions and examples will be given later.

Formulas of organic compounds

Formulas of organic compounds can be depicted in different ways. The composition of the molecule is reflected by the molecular (empirical) formula:

But this formula does not show the arrangement of atoms in the molecule, that is, the structure of the molecule of the substance. And in organic chemistry, this concept - the chemical structure of the molecule of a substance - is the most important! The sequence of connection of atoms in a molecule is shown by a graphic (structural) formula. For example, for a substance with the structure C4H10, you can write two formulas:

You can show all chemical bonds:

Such detailed graphic formulas clearly show that the carbon atom in organic molecules is tetravalent. When drawing up graphic formulas, you must first depict the carbon chain, for example:

Then use dashes to indicate the valence of each carbon atom:

Each carbon atom must have four lines!

Then fill the "free" valencies with hydrogen atoms (or other monovalent atoms or groups).

Now you can rewrite this formula in abbreviated form:

If you want to immediately write such a formula for butane, there is nothing complicated, you just need to count to four. Having depicted the carbon “skeleton”, you need to ask yourself the question: how many valencies (lines) does this particular carbon atom have?

Two. This means you need to add 2 hydrogen atoms:

It should be remembered that graphic formulas can be written in different ways. For example, the graphical formula for butane can be written as follows:

or like this:

and so on.

Since the sequence of arrangement of atoms has not been violated, these are formulas for the same compound(!) You can check yourself by making up the names of these compounds (see lesson 17.7). If the names of substances coincide, then these are formulas of the same substance.

Isomerism

By the middle of the 19th century, when quite a lot of organic compounds had been obtained and studied, organic chemists discovered an incomprehensible phenomenon: compounds with the same composition had different properties! For example, a gas that reacts with difficulty and does not react with Na is C2H6O. But there is a liquid that has the same composition and is very chemically active. In particular, this liquid of composition C2H6O actively reacted with Na, releasing hydrogen. Substances that are completely different in physical and chemical properties have the same molecular formula! Why? The answer to this question can be obtained using Butlerov’s theory of the structure of organic compounds, one of the provisions of which states: “The properties of organic compounds depend on the chemical structure of their molecules .

Since the chemical properties of the compounds under consideration are different, this means that their molecules have different structures. Let's try to create graphic formulas for these compounds. For a substance with the composition C2H6O, only two types of chains can be proposed:

Filling these “skeletons” with hydrogen atoms, we get:

Question. Which of these compounds is capable of reacting with Na, releasing hydrogen?

“O–H” bond , which is not present in molecule (II), is capable of such an interaction. And H2 gas is released because the “O–H” . If to form hydrogen it would be necessary to destroy the “C–H” , then since such bonds exist in both substances, H2 gas would be released in both cases. Thus, formula (I) reflects the structure of a liquid molecule, and formula (II) reflects the structure of a gas.

The existence of compounds that have the same composition but different chemical structures is called isomerism.

ISOMERS are compounds that have the same composition, but different chemical structures, and therefore different properties.

Therefore, molecules of organic compounds should be depicted using graphic (structural) formulas, since in this case the structure of the substance being studied will be visible, and therefore it will be clear how and due to what the chemical reaction occurs.

Exercise 17.1 . Find isomers among the following compounds:

Solution. Since the isomers have the same composition, we will determine the composition (molecular formulas) of all these compounds, that is, we will recalculate the number of carbon and hydrogen atoms:

Answer. Compounds a) and b) are isomeric to each other, since they have the same composition C4H10 , but different chemical structures.

Compounds c) and d) are isomeric to each other, since they have the same composition C5H12 , but different chemical structures.

Task 17.2. Find isomers among the following compounds:

A Brief History of Organic Chemistry

The history of chemistry dates back to ancient times, simultaneously with the beginning of human development. Since ancient times, man, not knowing the laws about the transformations of substances, learned to use them for his own benefit. The fire that our ancestors learned to produce made it possible not only to cook food, but also to obtain (albeit by accident) metals such as copper, lead, and tin. And later also pottery, by firing, glass, paints and much more.

Thus, a person gained knowledge about substances and their properties, but at the same time the number of questions to which he could not find an answer grew. Scientists of Ancient Greece made a great contribution to the development of chemistry. It was here that the first attempts to explain the processes themselves arose.

Thus, Anaximander and Heraclitus put forward the principle of “opposite”.

Empedocles identified 4 elements - water, air, fire and earth. And Aristotle suggested the possible interactions of these four elements.

Leucippus and Democritus believed that all substances consist of tiny particles - atoms and explained the occurring phenomena from the point of view of atomic theory.

Plato said that there are no pure substances, but only their modifications.

The next stage of development was alchemy , the basis of the study of which was metals, namely the desire to obtain gold from everything that came into hand. In addition, alchemists were concerned with the topic of creating an elixir of youth.

Although such organic substances as sugars, starch, alcohol, resins, oils, indigo, etc. have been known since ancient times, until the beginning of the 18th century, progress in their chemistry was very insignificant. Therefore, the beginning of the development of organic chemistry can be considered the 16th - 17th centuries.

In 1675, Lemery published his famous “Cours de Chimie”, in which he divided natural compounds into three classes: mineral, plant and animal. This classification was soon accepted. In 1784, Lavoisier first showed that all compounds obtained from plant and animal sources always contain at least carbon and hydrogen, and often nitrogen and phosphorus. Lavoisier's analytical work stimulated further research in this direction, as a result of which Lemery's classification inevitably had to undergo changes.

Lemery classified compounds by origin, but it has now been shown (no doubt thanks to improved analytical methods) that in some cases the same compound can be obtained from materials of both plant and animal origin. Thus, there is no difference between these two classes of compounds.

This led to the reclassification of substances into two groups:

• all those substances that could be obtained from vegetables or animals, that is, that were produced in a living organism, were classified as organic ;
• all those substances that were not obtained through a living organism are classified as inorganic .

At this stage of research into organic compounds, it turned out that there are certain differences between inorganic and organic compounds, for example, the complexity of the composition and the flammability of the latter.

Berzelius (1815) believed that organic compounds were produced from their elements according to laws different from those for inorganic compounds. This then led him to believe that organic substances were produced by the life force and that they could not be produced artificially.

However, in 1828, Wöhler converted ammonium cyanate (an inorganic compound) into urea, a substance that had hitherto only been obtained from animal sources. This synthesis somewhat weakened the distinction between organic and inorganic compounds. And this difference was completely ingrained by the synthesis of acetic acid from its elements by the scientist Kolbe in 1845, and the synthesis of methane by the scientist Berthelot in 1856. In 1861 A.M. Butlerov obtained a substance of the sugar class by acting on paraformaldehyde with lime water.

Now the question arises about the structure of organic compounds.
This question is fully revealed in the scientific theory created in 1861 by A.M. Butlerov: “Based on the idea that each chemical atom included in the composition of the body takes part in the formation of this latter and acts here with a certain amount of chemical force belonging to it, I call chemical structure the distribution of the action of this force, as a result of which chemical atoms, indirectly influencing each other on each other, combine to form a chemical particle" Categories Brief history of organic chemistry, ORGANIC CHEMISTRY

Homologues

From the same position of Butlerov’s theory of the structure of organic compounds, it follows that substances that have a similar (similar) molecular structure should also have similar (similar) properties. Organic compounds that have a similar structure, and therefore similar properties, form homologous series.

For example, hydrocarbons, the molecules of which have only one double bond, form a homologous series of alkenes:

and so on.

Hydrocarbons, whose molecules contain only simple bonds, form a homologous series of alkanes:

and so on.

Members of any homologous series are called HOMOLOGES.

Homologs are organic compounds that are similar in chemical structure and, therefore, in properties. Homologues differ from each other in composition by the CH2 or (CH2)n group.

Let us verify this using the example of the homologous series of alkenes:

Task 17.3 . Compare the composition of the members of the homologous series of alkanes (homologs of alkanes) and make sure that they differ in composition by the CH2 or (CH2)n group.

conclusions

Homologs are similar in structure, and therefore in properties; homologues differ in composition by the CH2 group. The CH2 group is called a homological difference.