Electronegativity oxidation state and valency. Electronegativity

Electronegativity is the property of a chemical element to attract electrons to its atom from the atoms of other elements with which this element forms a chemical bond in compounds.

At education chemical bond between atoms of different elements, the common electron cloud shifts to a more electronegative atom, due to which the bond becomes covalently polar, and with a large difference in electronegativity - ionic.

Electronegativity is taken into account when writing chemical formulas: in binary compounds, the symbol of the most electronegative element is written behind.

Electronegativity increases from left to right for elements of each period and decreases from top to bottom for elements of the same PS group.

Valency An element is called the property of its atoms to combine with a certain number of other atoms.

There are stoichiometric, electronic valency and coordination number. We will consider only the stoichiometric valency.

Stoichiometric valence shows how many atoms of another element attaches an atom of this element. The valence of hydrogen is taken as a unit of valence, because hydrogen is always monovalent. For example, in the compounds HCl, H 2 O, NH 3 (the correct spelling of ammonia H 3 N is already used in modern manuals), CH 4 chlorine is monovalent, oxygen is divalent, nitrogen is trivalent and carbon is tetravalent.

The stoichiometric valence of oxygen is usually 2. Since almost all elements form compounds with oxygen, it is convenient to use it as a standard for determining the valency of another element. For example, in the compounds Na 2 O, CoO, Fe 2 O 3, SO 3, sodium is monovalent, cobalt is bivalent, iron is trivalent, and sulfur is hexavalent.

In redox reactions, it will be important for us to determine the oxidation states of elements.

oxidation state element in a substance is called its stoichiometric valency, taken with a plus or minus sign.

Chemical elements are subdivided into elements of constant valence elements of variable valency.

1.3.3. Substances of molecular and non-molecular structure. Type of crystal lattice. The dependence of the properties of substances on their composition and structure.

Depending on the state in which compounds are in nature, they are divided into molecular and non-molecular. In molecular substances, the smallest structural particles are molecules. These substances have a molecular crystal lattice. In nonmolecular substances, the smallest structural particles are atoms or ions. Their crystal lattice is atomic, ionic or metallic.

The type of crystal lattice largely determines the properties of substances. For example, metals that have metal crystal lattice type, different from all other elements high plasticity, electrical and thermal conductivity. These properties, as well as many others - malleability, metallic luster, etc. due to a special type of bond between metal atoms - metallic bond. It should be noted that the properties inherent in metals appear only in the condensed state. For example, silver in the gaseous state does not have the physical properties of metals.

A special type of bond in metals - metallic - is due to a shortage of valence electrons, so they are common to the entire structure of the metal. The simplest model of the structure of metals assumed that the crystal lattice of metals consists of positive ions surrounded by free electrons, the movement of electrons occurs randomly, like gas molecules. However, such a model, while qualitatively explaining many properties of metals, turns out to be insufficient in quantitative verification. Further development of the theory of the metallic state led to the creation band theory of metals, which is based on the concepts of quantum mechanics.

At the nodes of the crystal lattice there are cations and metal atoms, and electrons move freely along the crystal lattice.

A characteristic mechanical property of metals is plastic, due to the peculiarities of the internal structure of their crystals. Plasticity is understood as the ability of bodies under the action of external forces to undergo deformation, which remains after the cessation of external influence. This property of metals allows them to be given various shapes during forging, rolled metal into sheets or drawn into wire.

The plasticity of metals is due to the fact that under external action, the layers of ions that form the crystal lattice are shifted relative to each other without breaking. This occurs as a result of the fact that the moved electrons, due to free redistribution, continue to carry out the connection between the ionic layers. Under mechanical action on solid with the atomic lattice, its individual layers are displaced and the cohesion between them is broken due to the breaking of covalent bonds.

ions, then these substances form ionic type of crystal lattice.

These are salts, as well as oxides and hydroxides of typical metals. These are hard, brittle substances, but their main quality : solutions and melts of these compounds conduct electricity .

If the nodes of the crystal lattice are atoms, then these substances form atomic type of crystal lattice(diamond, boron, silicon oxides of aluminum and silicon). By properties very hard and refractory, insoluble in water.

If the nodes of the crystal lattice are molecules, then these substances form (under normal conditions, gases and liquids: O 2, HCl; I 2 organic matter).

It is interesting to note the gallium metal, which melts at a temperature of 30 ° C. This anomaly is explained by the fact that Ga 2 molecules are located at the nodes of the crystal lattice and its properties become similar to substances that have a molecular crystal lattice.

Example. All non-metals of the group have a non-molecular structure:

1) carbon, boron, silicon; 2) fluorine, bromine, iodine;

3) oxygen, sulfur, nitrogen; 4) chlorine, phosphorus, selenium.

In nonmolecular substances, the smallest structural particles are atoms or ions. Their crystal lattice is atomic, ionic or metallic

At decision This question is easier to go from the contrary. If the nodes of the crystal lattice are molecules, then these substances form molecular type of crystal lattice(under normal conditions, gases and liquids: O 2, HCl; also I 2, rhombic sulfur S 8, white phosphorus P 4, organic substances). By properties, these are fragile low-melting compounds.

In the second answer there is fluorine gas, in the third - oxygen, nitrogen gases, in the fourth - chlorine gas. This means that these substances have a molecular crystal lattice and a molecular structure.

AT first answer, all substances are solid compounds under normal conditions and form an atomic lattice, which means they have a non-molecular structure.

Correct answer:1) carbon, boron, silicon

08. Electronegativity, oxidation state, oxidation and reduction

Let's discuss the meaning of extremely interesting concepts that exist in chemistry, and, as is often the case in science, quite confusing and used upside down. We will talk about "electronegativity", "oxidation states" and "redox reactions".

What does it mean - the concept is used upside down?

We will try to gradually talk about it.

Electronegativity shows us the redox properties of a chemical element. That is, its ability to take or give away free photons. And also whether this element is a source or absorber of energy (ether). Yang or Yin.

Oxidation state is a concept analogous to the concept of "electronegativity". It also characterizes the redox properties of the element. But there is a difference between them.

Electronegativity characterizes a single element. By itself, without being in the composition of any chemical compound. While the degree of oxidation characterizes its redox abilities precisely when the element is part of a molecule.

Let's talk a little about what is the ability to oxidize, and what is the ability to reduce.

Oxidation is the process of transferring free photons (electrons) to another element. Oxidation is not at all the removal of electrons, as it is now considered in science. . When an element oxidizes another element, it acts like an acid or oxygen (hence the name "oxidation"). To oxidize means to contribute to the destruction, decay, combustion of elements. . The ability to oxidize is the ability to cause the destruction of molecules by the energy transferred to them (free photons). Remember that energy always destroys matter.

It's amazing how long there are contradictions in logic in science that no one notices.

Here, for example: “Now we know that an oxidizing agent is a substance that acquires electrons, and a reducing agent is a substance that gives them away” (Encyclopedia of a young chemist, article “Redox reactions)”.

And then, two paragraphs below: “The strongest oxidizing agent is an electric current (a stream of negatively charged electrons)” (ibid.).

Those. the first quote says that an oxidizing agent is something that accepts electrons, and the second quote says that an oxidizing agent is something that gives it away.

And such erroneous, contradictory conclusions are forced to memorize in schools and institutes!

It is known that the best oxidizing agents are non-metals. Moreover, the smaller the period number and the larger the group number, the more pronounced the properties of the oxidizing agent. This is not surprising. We analyzed the reasons for this in the article devoted to the analysis of the periodic system, in the second part, where we talked about the color of nucleons. From group 1 to 8, the color of nucleons in the elements gradually changes from violet to red (if we also take into account the blue color of the d- and f-elements). The combination of yellow and red particles facilitates the return of accumulated free photons. Yellow ones accumulate, but hold weakly. And the reds contribute to the return. Giving off photons is the process of oxidation. But when some are red, there are no particles capable of accumulating photons. That is why the elements of group 8, the noble gases, are not oxidizing agents, unlike their neighbors, the halogens.

Recovery is a process opposite to oxidation. Now, in science, it is believed that when a chemical element receives electrons, it is restored. This point of view is quite understandable (but not accepted). When studying the structure chemical elements, they were found to emit electrons. They concluded that electrons are part of the elements. This means that the transfer of electrons to an element is, in a way, the restoration of its lost structure.

However, in reality, everything is not so.

Electrons are free photons. They are not nucleons. They are not part of the element's body. They are attracted, coming from outside, and accumulate on the surface of nucleons and between them. But their accumulation does not at all lead to the restoration of the structure of the element or molecule. On the contrary, these photons, emitted by their ether (energy), weaken and destroy bonds between elements. And this is an oxidation process, but not reduction.

Restoring a molecule is really taking energy (in this case, free photons) from it, not imparting it. Selecting photons, the reducing element compacts the substance - restores it.

The best reducing agents are metals. This property naturally follows from their qualitative and quantitative composition - their Fields of Attraction are the largest and there are necessarily many or enough particles on the surface of blue color.

One can even derive the following definition of metals.

Metal - This is a chemical element, in the composition of the surface layers of which there are necessarily blue particles.

BUT non-metal - this is an element in the composition of the surface layers of which there are no or almost no blue photons, and there are always red ones.

Metals are excellent at taking electrons with their strong attraction. And so they are restorers.

Let's give a definition of the concepts of "electronegativity", "oxidation state", "redox reactions", which can be found in textbooks on chemistry.

« Oxidation state is the conditional charge of an atom in a compound, calculated on the assumption that it consists only of ions. When defining this concept, it is conditionally assumed that the binding (valence) electrons pass to more electronegative atoms, and therefore the compounds consist, as it were, of positively and negatively charged ions. The oxidation state can have zero, negative, and positive values, which are usually placed above the element symbol at the top.

The zero value of the oxidation state is attributed to the atoms of the elements that are in the free state ... The negative value of the oxidation state is given to those atoms towards which the binding electron cloud (electron pair) is displaced. For fluorine in all its compounds, it is -1. Atoms that donate valence electrons to other atoms have a positive oxidation state. For example, for alkali and alkaline earth metals, it is respectively +1 and +2. In simple ions, it is equal to the charge of the ion. In most compounds, the oxidation state of hydrogen atoms is +1, but in metal hydrides (their compounds with hydrogen) and others, it is -1. For oxygen, the oxidation state is -2, but, for example, in combination with fluorine it will be +2, and in peroxide compounds -1. …

The algebraic sum of the oxidation states of atoms in a compound is zero, and in a complex ion it is the charge of the ion. …

The highest oxidation state is its highest positive value. For most elements, it is equal to the group number in periodic system and is an important quantitative characteristic of an element in its compounds. The lowest value of the oxidation state of an element that occurs in its compounds is commonly called the lowest oxidation state; all the rest are intermediate” (Encyclopedic Dictionary of a Young Chemist, article “Oxidation State”).

Here is the basic information about this concept. It is closely related to another term - "electronegativity".

« Electronegativity is the ability of an atom in a molecule to attract electrons involved in the formation of a chemical bond to itself ”(Encyclopedic Dictionary of a Young Chemist, article“ Electronegativity ”).

“Redox reactions are accompanied by a change in the oxidation state of the atoms that make up the reactants as a result of the movement of electrons from an atom of one of the reagents (reductant) to an atom of another. In redox reactions, oxidation (electron donation) and reduction (electron addition) occur simultaneously” (Chemical Encyclopedic Dictionary ed. I.L. Knunyants, article "Oxidation-reduction reactions").

In our opinion, there are many errors hidden in these three concepts.

Firstly , we believe that the formation of a chemical bond between two elements is not at all the process of sharing their electrons. A chemical bond is a gravitational bond. The electrons allegedly flying around the nucleus are free photons that accumulate on the surface of nucleons in the composition of the body of the element and between them. In order for two elements to bond, their free photons do not need to travel between the elements. This is not happening. In fact, a heavier element removes (attracts) free photons from a lighter one, and leaves them on itself (more precisely, on itself). And the zone of the lighter element, from which these photons were taken, is more or less exposed. Because of what, the attraction in this zone is manifested to a greater extent. And the lighter element is attracted to the heavier one. This is how a chemical bond occurs.

Secondly , modern chemistry sees the ability of elements to attract electrons to themselves distorted - inverted. It is believed that the greater the electronegativity of an element, the more it is able to attract electrons to itself. And fluorine and oxygen allegedly do this best of all - they attract foreign electrons to themselves. As well as other elements of the 6th and 7th groups.

In fact, this opinion is nothing more than a delusion. It is based on the misconception that the larger the group number, the heavier the elements. And also, the greater the positive charge of the nucleus. This is bullshit. Scientists still do not even bother to explain what, from their point of view, is a “charge”. Simply, as in numerology, they counted all the elements in order, and put down the amount of charge in accordance with the number. Great hike!

It is clear even to a child that gas is lighter than dense metal. How is it that in chemistry it is believed that gases are better at attracting electrons to themselves?

Dense metals, of course, they are better at attracting electrons.

Chemical scientists, of course, can keep the concept of "electronegativity" in use, since it is so commonly used. However, they will have to change its meaning to the exact opposite.

Electronegativity is the ability of a chemical element in a molecule to attract electrons to itself. And, of course, this ability is better expressed in metals than in non-metals.

As for the electric poles in the molecule, then, indeed, negative pole - these are non-metal elements that donate electrons, with smaller Attractive Fields. BUT positive are always elements with more pronounced metallic properties, with large fields of attraction.

Let's smile together.

Electronegativity - this is another, another attempt to describe the quality of a chemical element, along with the already existing mass and charge. As often happens, scientists from another field of science, in this case, chemistry, seem to distrust their fellow physicists, but rather simply because any person, making discoveries, goes his own way, and not just exploring the experience of others.

So it happened this time.

Mass and charge did not help chemists in any way to understand what happens in atoms when they interact with each other - and electronegativity was introduced - the ability of an element to attract electrons involved in the formation of a chemical bond. It should be recognized that the idea of ​​this concept is very true. With the only amendment that it reflects reality upside down. As we have already said, metals, and not non-metals, attract electrons best of all - due to the color features of surface nucleons. Metals are the best reducing agents. Nonmetals are oxidizers. Metals are taken, non-metals are given away. Metals are Yin, non-metals are Yang.

Esotericism comes to the aid of science in matters of comprehending the secrets of Nature.

Concerning oxidation states , then this is a good attempt to understand how the distribution of free electrons occurs within a chemical compound - a molecule.

If a chemical compound is homogeneous - that is, it is simple, its structure consists of elements of the same type - then everything is correct, indeed the oxidation state of any element in the compound is zero. Since there are no oxidizing agents and no reducing agents in this compound. And all elements are equal in quality. No one takes electrons, no one gives. Whether it is a dense substance, or a liquid, or a gas, it does not matter.

The oxidation state, like electronegativity, shows the quality of a chemical element - only within the framework of a chemical element. The oxidation state is designed to compare the quality of the chemical elements in the compound. In our opinion, the idea is good, but its implementation is not entirely satisfactory.

We are categorically against the whole theory and concept of the structure of chemical elements and the bonds between them. Well, at least because the number of groups, according to our ideas, should be more than 8. This means that the whole system is collapsing. And not only that. In general, counting the number of electrons in atoms “on the fingers” is somehow not serious.

In accordance with the current concept, it turns out that the smallest conditional charges are assigned to the strongest oxidizing agents - fluorine has a charge of -1 in all compounds, oxygen almost everywhere -2. And for very active metals - alkali and alkaline earth - these charges are +1 and +2, respectively. After all, this is completely illogical. Although, again, we understand very well the general scheme in accordance with which this was done - all for the sake of 8 groups in the table and 8 electrons in the outer energy level.

Already, at a minimum, the value of these charges for halogens and oxygen should have been the largest with a minus sign. And for alkali and alkaline earth metals, it is also large, only with a plus sign.

In any chemical compound there are elements that donate electrons - oxidizing agents, non-metals, a negative charge, and elements that take away electrons - reducing agents, metals, a positive charge. It is in this way that elements are compared, correlated with each other, and they try to determine their oxidation state.

However, to find out the degree of oxidation in this way, in our opinion, does not accurately reflect reality. It would be more correct to compare the electronegativity of elements in a molecule. After all, electronegativity is almost the same as the degree of oxidation (it characterizes the quality of only a single element).

You can take the scale of electronegativity and put down its values ​​in the formula for each element. And then it will be immediately clear which elements donate electrons and which ones take away. The element with the highest electronegativity in the compound, the negative pole, donates electrons. And the one whose electronegativity is the smallest - the positive pole - takes electrons.

If there are, say, 3 or 4 elements in a molecule, nothing changes. We also set the electronegativity values ​​and compare.

Although you should not forget to draw a model of the structure of the molecule. Indeed, in any compound, if it is not simple, that is, it does not consist of one type of elements, metals and non-metals are connected with each other, first of all. Metals take electrons from non-metals and bond with them. And from one non-metal element, 2 or more elements with more pronounced metallic properties can simultaneously take away electrons. So there is a complex, complex molecule. But this does not mean that in such a molecule the metal elements will enter into a strong bond with each other. Perhaps they will be located on opposite sides of each other. If nearby, they will be attracted. But a strong bond is formed only if one element is more metallic than the other. It is imperative that one element selects electrons - removes them. Otherwise, there will be no exposure of the element - liberation from free photons on the surface. The Field of Attraction will not fully manifest, and there will be no strong connection. This is a complex topic - the formation of chemical bonds, and we will not go into detail about this in this article.

We believe that we have covered in sufficient detail the topic devoted to the analysis of the concepts of "electronegativity", "oxidation state", "oxidation" and "reduction", and provided you with a lot of interesting information.