Valence oxidation state electronegativity examples. Valency and oxidation state. Oxidation state in almost all compounds

Video tutorial 2: Oxidation state chemical elements

Video tutorial 3: Valence. Determination of valency

Lecture: Electronegativity. Oxidation state and valency of chemical elements

Electronegativity

Electronegativity is the ability of atoms to attract electrons from other atoms to join them.

It is easy to judge the electronegativity of a particular chemical element using the table. Remember, in one of our lessons it was said that it increases when moving from left to right through periods in the periodic table and when moving from bottom to top through groups.

For example, the task was given to determine which element from the proposed series is the most electronegative: C (carbon), N (nitrogen), O (oxygen), S (sulfur)? We look at the table and find that this is O, because he is to the right and higher than the others.

What factors influence electronegativity? This:

The radius of an atom, the smaller it is, the higher the electronegativity.
The valence shell is filled with electrons; the more electrons there are, the higher the electronegativity.

Of all the chemical elements, fluorine is the most electronegative because it has a small atomic radius and there are 7 electrons in the valence shell.

Elements with low electronegativity include alkali and alkaline earth metals. They have large radii and very few electrons in the outer shell.

The electronegativity values of an atom cannot be constant, because it depends on many factors, including those listed above, as well as the degree of oxidation, which can be different for the same element. Therefore, it is customary to talk about the relativity of electronegativity values. You can use the following scales:

You will need electronegativity values when writing formulas for binary compounds consisting of two elements. For example, the formula of copper oxide Cu 2 O - the first element should be written down the one whose electronegativity is lower.

At the moment of formation of a chemical bond, if the electronegativity difference between the elements is greater than 2.0, a covalent polar bond is formed; if less, an ionic bond is formed.

Oxidation state

Oxidation state (CO)- this is the conditional or real charge of an atom in a compound: conditional - if the bond is polar covalent, real - if the bond is ionic.

An atom acquires a positive charge when it gives up electrons, and a negative charge when it accepts electrons.

Oxidation states are written above the symbols with a sign «+»/«-» . There are also intermediate COs. The maximum CO of an element is positive and equal to group number, and the minimum negative for metals is zero, for non-metals = (Group No. – 8). Elements with maximum CO only accept electrons, and elements with minimum CO only give up electrons. Elements that have intermediate COs can both give and receive electrons.

Let's look at some rules that should be followed to determine CO:

The CO of all simple substances is zero.

The sum of all CO atoms in a molecule is also equal to zero, since any molecule is electrically neutral.

In compounds with covalent non-polar bond CO is equal to zero (O 2 0), and with an ionic bond it is equal to the charges of ions (Na + Cl - sodium CO +1, chlorine -1). CO elements of compounds with a covalent polar bond are considered as with an ionic bond (H:Cl = H + Cl -, which means H +1 Cl -1).

Elements in a compound that have the greatest electronegativity have negative oxidation states, while those with the least electronegativity have positive oxidation states. Based on this, we can conclude that metals have only a “+” oxidation state.

Constant oxidation states:

Alkali metals +1.

All metals of the second group +2. Exception: Hg +1, +2.

Aluminum +3.

Hydrogen +1. Exception: hydrides of active metals NaH, CaH 2, etc., where the oxidation state of hydrogen is –1.
Oxygen –2. Exception: F 2 -1 O +2 and peroxides that contain the –O–O– group, in which the oxidation state of oxygen is –1.

When an ionic bond is formed, a certain transfer of electron occurs, from a less electronegative atom to an atom of greater electronegativity. Also, in this process, atoms always lose electrical neutrality and subsequently turn into ions. Integer charges are also formed. When a polar covalent bond is formed, the electron is transferred only partially, so partial charges arise.

Valence

Valence– is the ability of atoms to form n - number chemical bonds with atoms of other elements.

Valence is also the ability of an atom to hold other atoms near itself. As you know from school course chemistry, different atoms are bonded to each other by electrons from the outer energy level. An unpaired electron seeks a pair from another atom. These outer level electrons are called valence electrons. This means that valency can also be defined as the number of electron pairs connecting atoms to each other. Look at the structural formula of water: H – O – H. Each dash is an electron pair, which means it shows the valency, i.e. oxygen here has two lines, which means it is divalent, hydrogen molecules come from one line each, which means hydrogen is monovalent. When writing, valency is indicated by Roman numerals: O (II), H (I). Can also be indicated above the element.

Valence can be constant or variable. For example, in metal alkalis it is constant and equals I. But chlorine in various compounds exhibits valences of I, III, V, VII.

How to determine the valence of an element?

Let's turn again to periodic table. Metals of the main subgroups have a constant valency, so metals of the first group have valency I, the second - II. And metals of side subgroups have variable valency. It is also variable for non-metals. The highest valency of an atom is equal to group number, the lowest is equal to = group number - 8. A familiar formulation. Doesn't this mean that the valency coincides with the oxidation state? Remember, valence may coincide with the oxidation state, but these indicators are not identical to each other. Valency cannot have a =/- sign, and also cannot be zero.

The second method is to determine valency using a chemical formula, if the constant valency of one of the elements is known. For example, take the formula of copper oxide: CuO. Oxygen valence II. We see that for one oxygen atom in this formula there is one copper atom, which means that the valence of copper is equal to II. Now let's take a more complicated formula: Fe 2 O 3. The valency of the oxygen atom is II. There are three such atoms here, multiply 2*3 = 6. We found that there are 6 valences per two iron atoms. Let's find out the valency of one iron atom: 6:2=3. This means the valency of iron is III.

In addition, when it is necessary to estimate the "maximum valence", one should always start from the electronic configuration that is present in the "excited" state.

Chapter 3. CHEMICAL BOND

The ability of an atom of a chemical element to attach or replace a certain number of atoms of another element to form a chemical bond is called the element's valency.

Valence is expressed as a positive integer ranging from I to VIII. Valence equal to 0 or greater VIII no. Constant valency is exhibited by hydrogen (I), oxygen (II), alkali metals - elements of the first group of the main subgroup (I), alkaline earth elements - elements of the second group of the main subgroup (II). Atoms of other chemical elements exhibit variable valency. So, transition metals– elements of all secondary subgroups – exhibit from I to III. For example, iron in compounds can be di- or trivalent, copper - mono- and divalent. The atoms of other elements can exhibit a valence in compounds equal to the group number and intermediate valences. For example, the highest valence of sulfur is IV, the lowest is II, and the intermediate ones are I, III and IV.

Valency is equal to the number of chemical bonds by which an atom of a chemical element is connected to atoms of other elements in chemical compound. A chemical bond is indicated by a dash (–). Formulas that show the order of connection of atoms in a molecule and the valency of each element are called graphical.

Oxidation state is the conditional charge of an atom in a molecule, calculated under the assumption that all bonds are ionic in nature. This means that a more electronegative atom, by displacing one electron pair completely towards itself, acquires a charge of 1–. Nonpolar covalent bonds between like atoms do not contribute to the oxidation state.

To calculate the oxidation state of an element in a compound, one should proceed from the following provisions:

1) the oxidation states of elements in simple substances are assumed to be zero (Na 0; O 2 0);

2) algebraic sum the oxidation states of all atoms that make up the molecule are zero, and in a complex ion this sum is equal to the charge of the ion;

3) atoms have a constant oxidation state: alkali metals(+1), alkaline earth metals, zinc, cadmium (+2);

4) the oxidation state of hydrogen in compounds is +1, except for metal hydrides (NaH, etc.), where the oxidation state of hydrogen is –1;

5) the oxidation state of oxygen in compounds is –2, except for peroxides (–1) and oxygen fluoride OF2 (+2).

The maximum positive oxidation state of an element usually coincides with its group number in the periodic table. The maximum negative oxidation state of an element is equal to the maximum positive oxidation state minus eight.

The exceptions are fluorine, oxygen, iron: their highest oxidation state is expressed by a number whose value is lower than the number of the group to which they belong. Elements of the copper subgroup, on the contrary, have the highest oxidation state more than one, although they belong to group I.

Atoms of chemical elements (except noble gases) can interact with each other or with atoms of other elements forming b.m. complex particles - molecules, molecular ions and free radicals. The chemical bond is due electrostatic forces between atoms , those. forces of interaction between electrons and atomic nuclei. In the formation of a chemical bond between atoms main role play valence electrons, i.e. electrons located in the outer shell.

I.Valence (repetition)

Valence is the ability of atoms to attach to themselves a certain number of other atoms.

Rules for determining valence
elements in connections

1. Valence hydrogen mistaken for I(unit). Then, in accordance with the formula of water H 2 O, two hydrogen atoms are attached to one oxygen atom.

2. Oxygen in its compounds always exhibits valence II. Therefore, the carbon in the compound CO 2 (carbon dioxide) has a valence of IV.

3. Higher valence equal to group number .

4. Lowest valency is equal to the difference between the number 8 (the number of groups in the table) and the number of the group in which this element is located, i.e. 8 - N groups .

5. For metals located in “A” subgroups, the valence is equal to the group number.

6. Nonmetals generally exhibit two valences: higher and lower.

For example: sulfur has the highest valency VI and the lowest (8 – 6) equal to II; phosphorus exhibits valences V and III.

7. Valence can be constant or variable.

The valency of elements must be known in order to compose chemical formulas of compounds.

Remember!

Features of compilation chemical formulas connections.

1) The lowest valence is shown by the element that is located to the right and above in D.I. Mendeleev’s table, and the highest valence is shown by the element located to the left and below.

For example, in combination with oxygen, sulfur exhibits the highest valency VI, and oxygen the lowest valency II. Thus, the formula for sulfur oxide will be SO 3.

In the compound of silicon with carbon, the first exhibits the highest valency IV, and the second - the lowest IV. So the formula– SiC. This is silicon carbide, the basis of refractory and abrasive materials.

2) The metal atom comes first in the formula.

2) In the formulas of compounds, the non-metal atom exhibiting the lowest valency always comes in second place, and the name of such a compound ends in “id”.

For example, Sao – calcium oxide, NaCl – sodium chloride, PbS – lead sulfide.

Now you can write the formulas for any compounds of metals and non-metals.

3) The metal atom is placed first in the formula.

II. Oxidation state (new material)

Oxidation state- this is a conditional charge that an atom receives as a result of the complete donation (acceptance) of electrons, based on the condition that all bonds in the compound are ionic.

Let's consider the structure of fluorine and sodium atoms:

F +9)2)7

Na +11)2)8)1

- What can be said about the completeness of the external level of fluorine and sodium atoms?

- Which atom is easier to accept, and which is easier to give away valence electrons in order to complete the outer level?

Do both atoms have an incomplete outer level?

It is easier for a sodium atom to give up electrons, and for a fluorine atom to accept electrons before completing the outer level.

F 0 + 1ē → F -1 (a neutral atom accepts one negative electron and acquires an oxidation state of “-1”, turning into negatively charged ion - anion )

Na 0 – 1ē → Na +1 (a neutral atom gives up one negative electron and acquires the oxidation state “+1”, turning into positively charged ion - cation )

How to determine the oxidation state of an atom in PSHE D.I. Mendeleev?

Determination rules oxidation state of an atom in PSHE D.I. Mendeleev:

1. Hydrogen usually exhibits oxidation number (CO) +1 (exception, compounds with metals (hydrides) – in hydrogen, CO is equal to (-1) Me + n H n -1)

2. Oxygen usually exhibits SO -2 (exceptions: O +2 F 2, H 2 O 2 -1 - hydrogen peroxide)

3. Metals only show + n positive CO

4. Fluorine always exhibits CO equal -1 (F -1)

5. For elements main subgroups:

Higher CO (+) = group number N groups

Lowest CO (-) = N groups – 8

Rules for determining the oxidation state of an atom in a compound:

I. Oxidation state free atoms and atoms in molecules simple substances equal to zero - Na 0 , P 4 0 , O 2 0

II. IN complex substance the algebraic sum of the COs of all atoms, taking into account their indices, is equal to zero = 0 , and in complex ion its charge.

For example, H +1 N +5 O 3 -2 : (+1)*1+(+5)*1+(-2)*3 = 0

2- : (+6)*1+(-2)*4 = -2

Task 1 – determine the oxidation states of all atoms in the formula of sulfuric acid H 2 SO 4?

1. Let’s put the known oxidation states of hydrogen and oxygen, and take CO of sulfur as “x”

H +1 S x O 4 -2

(+1)*1+(x)*1+(-2)*4=0

X = 6 or (+6), therefore, sulfur has C O +6, i.e. S+6

Task 2 – determine the oxidation states of all atoms in the formula of phosphoric acid H 3 PO 4?

1. Let’s put the known oxidation states of hydrogen and oxygen, and take the CO of phosphorus as “x”

H 3 +1 P x O 4 -2

2. Let’s compose and solve the equation according to rule (II):

(+1)*3+(x)*1+(-2)*4=0

X = 5 or (+5), therefore, phosphorus has C O +5, i.e. P+5

Task 3 – determine the oxidation states of all atoms in the formula of ammonium ion (NH 4) +?

1. Let’s put the known oxidation state of hydrogen, and take CO2 of nitrogen as “x”

(N x H 4 +1) +

2. Let’s compose and solve the equation according to rule (II):

(x)*1+(+1)*4=+1

X = -3, therefore, nitrogen has C O -3, i.e. N-3

08. Electronegativity, oxidation number, oxidation and reduction

Let's discuss the meaning of extremely interesting concepts that exist in chemistry, and as often happens in science, they are quite confusing and used upside down. We will talk about “electronegativity”, “oxidation state” and “redox reactions”.

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

We will try to gradually talk about this.

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 similar to the concept of “electronegativity”. It also characterizes the redox properties of the element. But there is the following difference between them.

Electronegativity gives a characteristic to an individual element. By itself, without being part of any chemical compound. While the oxidation state characterizes its redox abilities precisely when the element is part of a molecule.

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

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

It's amazing how long contradictions in logic exist in science without anyone noticing.

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 electric current(flow of negatively charged electrons)” (ibid.).

Those. The first quote says that an oxidizing agent is something that accepts electrons, and the second quote is an oxidizing agent that is something that donates electrons.

And such erroneous, contradictory conclusions are forced to be memorized 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 examined the reasons for this in an article devoted to the analysis periodic table, in the second part, where they talked about the color of nucleons. From group 1 to group 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 release of accumulated free photons. Yellow accumulates, but retains it weakly. And red ones promote returns. Giving up photons is the process of oxidation. But when some are red, then there are no particles capable of accumulating photons. This is why group 8 elements, the noble gases, are not oxidizing agents, unlike their neighbors, the halogens.

Recovery is a process opposite to oxidation. Nowadays, in science, it is believed that when a chemical element receives electrons, it is reduced. This point of view can be understood (but not accepted). When studying the structure of chemical elements, it was discovered that they emit electrons. We concluded that electrons are part of the elements. This means that transferring electrons to an element is, in a way, restoring its lost structure.

However, in reality this is not the case.

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 lead to restoration of the structure of an element or molecule. On the contrary, these photons, with the ether (energy) they emit, weaken and destroy the bonds between elements. And this is a process of oxidation, but not reduction.

To restore a molecule, in reality, is to take energy from it (in this case, free photons), and not to impart it. By 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 Attraction Fields are the largest and there are necessarily many or enough particles on the surface blue.

You can even derive the following definition of metals.

Metal is a chemical element, the composition of the surface layers of which necessarily contains blue particles.

A 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, with their strong attraction, are great at removing electrons. And that's why they are restorers.

Let us define the concepts “electronegativity”, “oxidation state”, “redox reactions”, which can be found in chemistry textbooks.

« Oxidation state – 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 conventionally assumed that the bonding (valence) electrons move to more electronegative atoms, and therefore the compounds consist of positively and negatively charged ions. The oxidation number can have zero, negative and positive values, which are usually placed above the element symbol at the top.

A zero oxidation state value is assigned to atoms of elements that are in a free state... A negative oxidation state value is assigned to those atoms towards which the connecting electron cloud (electron pair) shifts. For fluorine in all its compounds it is equal to -1. Atoms that donate valence electrons to other atoms have a positive oxidation state. For example, for alkali and alkaline earth metals it is equal to +1 and +2, respectively. 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. Oxygen has an oxidation state of -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. ...

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

Here are the basic information regarding this concept. It is closely related to another term – “electronegativity”.

« Electronegativity “is the ability of an atom in a molecule to attract electrons that participate in the formation of a chemical bond” (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 reacting substances as a result of the movement of electrons from an atom of one of the reagents (reducing agent) to an atom of another. In redox reactions, oxidation (donation of electrons) and reduction (gain of electrons) occur simultaneously” (Chemical Encyclopedic Dictionary edited by I.L. Knunyants, article “Redox 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 a process of sharing their electrons. A chemical bond is a gravitational bond. The electrons supposedly flying around the nucleus are free photons that accumulate on the surface of nucleons within the body of the element and between them. In order for a connection to arise between two elements, their free photons do not need to travel between the elements. This doesn't happen. In fact, more heavy element removes (attracts) free photons from the lighter one, and leaves them with itself (more precisely, on itself). And the zone of the lighter element from which these photons were taken is exposed to one degree or another. Because of this, attraction in this zone is more pronounced. 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 in a distorted way - inverted. It is believed that the greater the electronegativity of an element, the more capable it is of attracting electrons. And fluorine and oxygen supposedly do this best - they attract other people's electrons. As well as other elements of groups 6 and 7.

In fact, this opinion is nothing more than a misconception. It is based on the misconception that the higher the group number, the heavier the elements. And also, the greater the positive charge of the nucleus. This is nonsense. Scientists still don’t even bother to explain what constitutes a “charge” from their point of view. Simply, as in numerology, we counted all the elements in order and assigned the charge value in accordance with the number. Great hike!

It is clear to a child that gas is lighter dense metal. How did it happen that in chemistry it is believed that gases attract electrons better?

Dense metals, of course, attract electrons better.

Chemical scientists, of course, can keep the concept of “electronegativity” in use, since it is so common. 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, naturally, 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. A positive – these are always elements with more pronounced metallic properties, with larger Attraction Fields.

Let's smile together.

Electronegativity - this is yet another, yet 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 not trust their physicist colleagues, but rather simply because any person, making discoveries, follows his own path, and not simply exploring the experience of others.

That's what happened this time too.

Mass and charge did not help chemists 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 must be admitted that the idea behind this concept is very correct. With the only amendment that it reflects reality in an inverted form. As we have already said, metals, rather than non-metals, attract electrons best due to the color characteristics of surface nucleons. Metals are the best reducing agents. Nonmetals are oxidizing agents. Metals are taken away, non-metals are given away. Metals are Yin, non-metals are Yang.

Esotericism comes to the aid of science in understanding the secrets of Nature.

Regarding 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 this compound contains no oxidizing agents and no reducing agents. And all elements are equal in quality. Nobody takes away electrons, nobody gives them away. Be it dense substance, or liquid, or gas - it doesn’t matter.

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

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

In accordance with the current concept, it turns out that the strongest oxidizing agents are assigned the smallest conventional charges - fluorine has a charge of -1 in all compounds, oxygen has a charge of -2 almost everywhere. And for very active metals - alkali and alkaline earth - these charges are +1 and +2, respectively. After all, this is completely illogical. Although, we repeat, 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 at the external energy level.

At a minimum, the magnitude of these charges on 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, negative charge, and elements that take away electrons - reducing agents, metals, positive charge. It is in this way that they compare elements, relate them to each other, and try to determine their oxidation state.

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

You can take the electronegativity scale and put its values in the formula for each element. And then it will be immediately clear which elements give up electrons and which take them away. The element whose electronegativity in the compound is greatest—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 element, first of all, metals and non-metals are connected to each other. Metals take electrons from nonmetals and bond with them. And from one non-metal element 2 or 2 electrons can be simultaneously taken away larger number elements with more pronounced metallic properties. This is how a complex, complex molecule arises. But this does not mean that in such a molecule the metal elements will form a strong bond with each other. Perhaps they will be located on opposite sides of each other. If they are 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, the element will not be exposed—freed from free photons on the surface. The Field of Attraction will not fully manifest itself, and there will be no strong connection. This complex topic– the formation of chemical bonds, and we will not talk about this in detail 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 your attention with a lot of interesting information.

From the book Autobiography of a Yoga author Yogananda Paramahansa

Chapter 23 I'm Getting a University Degree - You ignore the textbook's philosophical definitions, no doubt counting on some effortless "intuition" to guide you through all the exams. But if you do not urgently contact more scientific method then I'll have to

From the book Guided Dreams author Mir Elena

Restoration “When the One sign of individuation arises, essence and life are divided into two. From this moment on, unless final peace is achieved, essence and life will never see each other again." William, “The Secret of the Golden Flower” After college

From the book The Riddle of the Great Sphinx by Barbarin Georges

Restoration of the statue The actual age of the Great Sphinx dates back to the beginning of the Adamic era. At the very least, he is a contemporary of the pyramids, the ensemble of which, as we will see, he completed with himself. The image of the Great Sphinx has been subjected to over the past centuries

From the book Golden Rules of Feng Shui. 10 simple steps to success, well-being and longevity author Ogudin Valentin Leonidovich

The degree of negative influence of external objects The greatest negative influence is exerted by external objects located directly in front of the entrance to the house. But the more they are located at an angle to the entrance, the weaker their influence becomes. The object is directly

From the book The Complete History of Freemasonry in One Book author Sparov Victor

Initiation to the degree of Master (Mystery performance of the third degree) Below we present, as in the case of initiation into the Masons and the assignment of the degree of Apprentice, a “mystery play” of the third degree, performed during initiation to the degree of Master. Q: Are you a master? O.: Yes,

From the book Divine Evolution. From the Sphinx to Christ author Shure Edward

First degree: Preparation. The Sermon on the Mount and the Kingdom of God The work of Christ begins with the Galilean idyll and the announcement of the “kingdom of God.” This prediction points us to his popular teachings. At the same time, it is a preparation for more sublime

From the book Vampires in Russia. Everything you need to know about them! author Bauer Alexander

Second degree of initiation (purification). Miraculous healings. Christian therapy In all the ancient mysteries, moral and intellectual preparation was followed by a purification of the soul, which should revive new organs in it and subsequently give it the ability to

From the book Cagliostro and Egyptian Freemasonry author Kuzmishin E. L.

How to determine the degree of blood loss When a vampire drinks blood, he drinks from half a liter to one and a half liters of blood at a time. The human body contains only five to six liters of blood, so such blood loss is not necessarily life-threatening. However, a vampire can

From the book Book of Secrets. The Incredibly Obvious on Earth and Beyond author Vyatkin Arkady Dmitrievich

Apprentice Degree Admission to the Apprentice Degree Decoration of the box and vestments The walls and ceiling of the box should be hung with blue and white material without gilding. Above the head of the Worshipful Master is a triangle surrounded by radiance with his name inscribed in its center

From the book Healing the Soul. 100 meditation techniques, healing exercises and relaxation author Rajneesh Bhagwan Shri

Admission to the degree of Apprentice Decoration of the box and vestments The walls and ceiling of the box should be hung with blue and white material without gilding. Above the head of the Worshipful Master is a triangle surrounded by radiance with the name "Jehovah" inscribed in its center, embroidered

From the book Modeling the Future in a Dream author Mir Elena

Fellow Degree

From the book of Kabbalah. Upper world. The beginning of the journey author Laitman Michael

Inner Temple Master's Degree

From the author's book

Masochism as an extreme degree of voluntary vampirism In this sense, masochism is similar to codependency. Masochists are people who derive pleasant sensations from their own physical and mental suffering. In other words, they like to be beaten, scolded, mocked

From the author's book

Restoring rhythm...Set the same time to go to bed - if it's eleven every night, then it's eleven. This is the first thing: set a certain time, and soon the body will be able to fall into this rhythm. Do not change this time, otherwise you will confuse the body. Body

From the author's book

Recovery After being transferred from college, working as an engineer at a closed enterprise, I realized that I was out of place, so I decided to change my profession and entered the jazz school of improvisation, and later music school to the classical department.

From the author's book

7.5. The degree of awareness of evil As explained in the article “The Giving of the Torah,” pleasure and bliss are determined by the degree of similarity to the Creator in properties, and suffering and impatience are determined by the degree of difference from the Creator. Accordingly, selfishness is disgusting and unbearably painful to us,

Part 1. Task A5.

Checked elements: Electronegativity. Oxidation state and

valence of chemical elements.

Electronegativity-a quantity characterizing the ability of an atom to polarize covalent bonds. If in a diatomic molecule A - B the electrons forming the bond are attracted to atom B more strongly than to atom A, then atom B is considered more electronegative than A.

The electronegativity of an atom is the ability of an atom in a molecule (compound) to attract electrons that bind it to other atoms.

The concept of electronegativity (EO) was introduced by L. Pauling (USA, 1932). Quantitative characteristics electronegativity of an atom is very arbitrary and cannot be expressed in any units physical quantities, therefore, several scales have been proposed to quantify EO. The scale of relative EO has received the greatest recognition and distribution:

Electronegativity values of elements according to Pauling

Electronegativity χ (Greek chi) is the ability of an atom to hold external (valence) electrons. It is determined by the degree of attraction of these electrons to the positively charged nucleus.

This property manifests itself in chemical bonds as a shift of bond electrons towards a more electronegative atom.

The electronegativity of the atoms involved in the formation of a chemical bond is one of the main factors that determines not only the TYPE, but also the PROPERTIES of this bond, and thereby affects the nature of the interaction between atoms during a chemical reaction.

In L. Pauling’s scale of relative electronegativities of elements (compiled on the basis of the bond energies of diatomic molecules), metals and organogenic elements are arranged in the following row:

The electronegativity of elements obeys periodic law: it grows from left to right in periods and from bottom to top in the main subgroups of the Periodic Table of Elements D.I. Mendeleev.

Electronegativity is not an absolute constant of an element. It depends on the effective charge of the atomic nucleus, which can change under the influence of neighboring atoms or groups of atoms, the type of atomic orbitals and the nature of their hybridization.

Oxidation state is the conditional charge of the atoms of a chemical element in a compound, calculated from the assumption that the compounds consist only of ions.

Oxidation states can have a positive, negative or zero value, and the sign is placed before the number: -1, -2, +3, in contrast to the charge of the ion, where the sign is placed after the number.

In molecules, the algebraic sum of the oxidation states of elements, taking into account the number of their atoms, is equal to 0.

The oxidation states of metals in compounds are always positive, the highest oxidation state corresponds to the number of the group of the periodic system where the element is located (excluding some elements: gold Au+3 (group I), Cu+2 (II), from group VIII the oxidation state +8 can only osmium Os and ruthenium Ru.

The degrees of non-metals can be both positive and negative, depending on which atom it is connected to: if with a metal atom it is always negative, if with a non-metal it can be both + and - (you will learn about this when studying a number of electronegativities) . The highest negative oxidation state of non-metals can be found by subtracting from 8 the number of the group in which the element is located, the highest positive is equal to the number of electrons per outer layer(the number of electrons corresponds to the group number).

The oxidation states of simple substances are 0, regardless of whether it is a metal or a non-metal.

Table showing constant powers for the most commonly used elements:

The degree of oxidation (oxidation number, formal charge) is an auxiliary conventional value for recording the processes of oxidation, reduction and redox reactions, numerical value electric charge, assigned to an atom in a molecule under the assumption that the electron pairs performing the bond are completely biased towards more electronegative atoms.

Ideas about the degree of oxidation form the basis for the classification and nomenclature of inorganic compounds.

The degree of oxidation is a purely arbitrary value that has no physical meaning, but characterizing the formation of a chemical bond of interatomic interaction in a molecule.

Valence of chemical elements -(from Latin valens - having strength) - the ability of atoms of chemical elements to form a certain number of chemical bonds with atoms of other elements. In compounds formed using ionic bonds, the valence of atoms is determined by the number of electrons added or given up. In compounds with covalent bonds, the valence of atoms is determined by the number of shared electron pairs formed.

Constant valency:

Remember:

The oxidation state is the conditional charge of the atoms of a chemical element in a compound, calculated from the assumption that all bonds are ionic in nature.

1. Item in simple matter has zero oxidation state. (Cu, H2)

2. The sum of the oxidation states of all atoms in a molecule of a substance is zero.

3. All metals have a positive oxidation state.

4. Boron and silicon in compounds have positive oxidation states.

5. Hydrogen has an oxidation state (+1) in compounds. Excluding hydrides

(hydrogen compounds with metals of the main subgroup of the first and second groups, oxidation state -1, for example Na + H -)

6. Oxygen has an oxidation state (-2), with the exception of the compound of oxygen with fluorine OF2, the oxidation state of oxygen (+2), the oxidation state of fluorine (-1). And in peroxides H 2 O 2 - the oxidation state of oxygen (-1);

7. Fluorine has an oxidation state (-1).

Electronegativity is the property of HeMe atoms to attract common electron pairs. Electronegativity has the same dependence as Non-metallic properties: across the period (from left to right) it increases, across the group (from above) it decreases.

The most electronegative element is Fluorine, then Oxygen, Nitrogen...etc....

Algorithm for completing the task in demo version:

Exercise:

The chlorine atom is located in group 7, so it can have maximum degree oxidation +7.

The chlorine atom exhibits this degree of oxidation in the substance HClO4.

Let's check this: The two chemical elements hydrogen and oxygen have constant oxidation states and are equal to +1 and -2, respectively. The number of oxidation states for oxygen is (-2)·4=(-8), for hydrogen (+1)·1=(+1). The number of positive oxidation states is equal to the number of negative ones. Therefore (-8)+(+1)=(-7). This means that the chromium atom has 7 positive degrees; we write down the oxidation states above the elements. The oxidation state of chlorine is +7 in the HClO4 compound.

Answer: Option 4. The oxidation state of chlorine is +7 in the HClO4 compound.

Various formulations of task A5:

3. Oxidation state of chlorine in Ca(ClO 2) 2

1) 0 2) -3 3) +3 4) +5

4.The element has the lowest electronegativity

5. Manganese has the lowest oxidation state in the compound

1)MnSO 4 2)MnO 2 3)K 2 MnO 4 4)Mn 2 O 3

6. Nitrogen exhibits an oxidation state of +3 in each of the two compounds

1)N 2 O 3 NH 3 2)NH 4 Cl N 2 O 3)HNO 2 N 2 H 4 4)NaNO 2 N 2 O 3

7.The valency of the element is

1) the number of σ bonds it forms

2) the number of connections it forms