Covalent bond(from the Latin "co" together and "vales" being valid) is carried out at the expense of an electron pair belonging to both atoms. Formed between atoms of non-metals.

The electronegativity of non-metals is quite large, so that during the chemical interaction of two atoms of non-metals, complete transfer of electrons from one to the other (as in the case) is impossible. In this case, it is necessary to combine the electrons to perform.

As an example, let us discuss the interaction of hydrogen and chlorine atoms:

H 1s 1 - one electron

Cl 1s 2 2s 2 2 p 6 3 s 2 3 p 5 - seven electrons at the outer level

Each of the two atoms lacks one electron in order to have a complete outer electron shell. And each of the atoms allocates "for general use" one electron. This enforces the octet rule. This is best portrayed using Lewis formulas:

Formation of a covalent bond

The shared electrons now belong to both atoms. The hydrogen atom has two electrons (its own and shared electron of the chlorine atom), and the chlorine atom has eight electrons (its own plus the shared electron of the hydrogen atom). These two shared electrons form a covalent bond between the hydrogen and chlorine atoms. The particle formed by the bonding of two atoms is called molecule.

Non-polar covalent bond

A covalent bond can also form between two the same atoms. For example:

This diagram explains why hydrogen and chlorine exist as diatomic molecules. Thanks to the pairing and sharing of two electrons, it is possible to fulfill the octet rule for both atoms.

In addition to single bonds, a double or triple covalent bond can be formed, as, for example, in the molecules of oxygen O 2 or nitrogen N 2. Nitrogen atoms have five valence electrons, therefore, three more electrons are required to complete the shell. This is accomplished by sharing three pairs of electrons as shown below:

Covalent compounds are usually gases, liquids, or relatively low melting solids. One of the rare exceptions is diamond, which melts above 3,500 ° C. This is due to the structure of diamond, which is a continuous lattice of covalently bonded carbon atoms, rather than a collection of individual molecules. Virtually any diamond crystal, regardless of its size, is one huge molecule.

A covalent bond occurs when the electrons of two nonmetal atoms combine. The resulting structure is called a molecule.

Polar covalent bond

In most cases, two covalently bonded atoms have different electronegativity and shared electrons do not belong to two atoms equally. Most of the time, they are closer to one atom than to another. In a hydrogen chloride molecule, for example, the electrons forming a covalent bond are located closer to the chlorine atom, since its electronegativity is higher than that of hydrogen. However, the difference in the ability to attract electrons is not so great that a complete transfer of an electron from a hydrogen atom to a chlorine atom occurs. Therefore, the bond between hydrogen and chlorine atoms can be viewed as a cross between an ionic bond (complete electron transfer) and a non-polar covalent bond (symmetric arrangement of a pair of electrons between two atoms). The partial charge on atoms is denoted by the Greek letter δ. This connection is called polar covalent bond, and the hydrogen chloride molecule is said to be polar, that is, it has a positively charged end (hydrogen atom) and a negatively charged end (chlorine atom).

The table below lists the main types of bonds and examples of substances:

Exchange and donor-acceptor mechanism of covalent bond formation

1) Exchange mechanism. Each atom gives one unpaired electron to a common electron pair.

2) Donor-acceptor mechanism. One atom (donor) provides an electron pair, and another atom (acceptor) provides a free orbital for this pair.

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You know that atoms can combine with each other to form both simple and complex substances. In this case, various types of chemical bonds are formed: ionic, covalent (non-polar and polar), metallic and hydrogen. One of the most essential properties of atoms of elements that determine which bond is formed between them - ionic or covalent - it is electronegativity, i.e. the ability of atoms in a compound to attract electrons to themselves.

A conditional quantitative assessment of electronegativity is given by the scale of relative electronegativity.

In periods, there is a general tendency towards an increase in the electronegativity of elements, and in groups - their fall. Elements by electronegativity are arranged in a row, on the basis of which the electronegativities of elements located in different periods can be compared.

The type of chemical bond depends on how large the difference in the values ​​of electronegativities of the connecting atoms of elements is. The more the atoms of the elements forming the bond differ in electronegativity, the more polar the chemical bond is. It is impossible to draw a sharp line between the types of chemical bonds. In most compounds, the type of chemical bond is intermediate; for example, a highly polar covalent chemical bond is close to an ionic bond. Depending on which of the limiting cases the chemical bond is closer in nature to, it is referred to either an ionic or a covalent polar bond.

An ionic bond is formed by the interaction of atoms, which differ sharply from each other in electronegativity. For example, typical metals lithium (Li), sodium (Na), potassium (K), calcium (Ca), strontium (Sr), barium (Ba) form an ionic bond with typical non-metals, mainly halogens.

In addition to alkali metal halides, ionic bonds are also formed in compounds such as alkalis and salts. For example, in sodium hydroxide (NaOH) and sodium sulfate (Na 2 SO 4), ionic bonds exist only between sodium and oxygen atoms (other bonds are covalent polar).

When atoms with the same electronegativity interact, molecules with a covalent non-polar bond are formed. Such a bond exists in the molecules of the following simple substances: H 2, F 2, Cl 2, O 2, N 2. The chemical bonds in these gases are formed by common electron pairs, i.e. when the corresponding electron clouds overlap, due to the electron-nuclear interaction, which is carried out when atoms approach.

When composing the electronic formulas of substances, it should be remembered that each common electron pair is a conditional image of an increased electron density resulting from the overlap of the corresponding electron clouds.

In the interaction of atoms, the values ​​of the electroretequencies of which differ, but not sharply, a shift of the common electron pair occurs to a more electronegative atom. It is the most common type of chemical bond found in both inorganic and organic compounds.

The covalent bonds fully include those bonds that are formed by the donor-acceptor mechanism, for example, in the ions of hydronium and ammonium.

Metallic bond.

The bond that forms as a result of the interaction of relatively free electrons with metal ions is called a metal bond. This type of bond is typical for simple substances - metals.

The essence of the metal bond formation process is as follows: metal atoms easily donate valence electrons and turn into positive charged ions. Relatively free electrons, detached from the atom, move between the positive metal ions. A metallic bond arises between them, that is, the electrons seem to cement the positive ions of the crystal lattice of metals.

Hydrogen bond.

The bond that forms between the hydrogen atoms of one molecule and the atom of a strongly electronegative element(O, N, F) another molecule is called a hydrogen bond.

The question may arise: why exactly hydrogen forms such a specific chemical bond?

This is because the atomic radius of hydrogen is very small. In addition, when displacing or completely giving up its only electron, hydrogen acquires a relatively high positive charge, due to which the hydrogen of one molecule interacts with the atoms of electronegative elements that have a partial negative charge that goes into the composition of other molecules (HF, H2O, NH3) ...

Let's look at some examples. We usually depict the composition of water with the chemical formula H 2 O. However, this is not entirely accurate. It would be more correct to denote the composition of water by the formula (H 2 O) n, where n = 2,3,4, etc. This is explained by the fact that individual water molecules are linked through hydrogen bonds.

The hydrogen bond is usually denoted by dots. It is much weaker than ionic or covalent bonds, but stronger than normal intermolecular interactions.

The presence of hydrogen bonds explains the increase in water volume with decreasing temperature. This is due to the fact that as the temperature decreases, the molecules become stronger and therefore the density of their "packing" decreases.

When studying organic chemistry, the following question arose: why are the boiling points of alcohols much higher than the corresponding hydrocarbons? This is explained by the fact that hydrogen bonds are also formed between alcohol molecules.

An increase in the boiling point of alcohols also occurs due to the enlargement of their molecules.

The hydrogen bond is also typical for many other organic compounds (phenols, carboxylic acids, etc.). From courses in organic chemistry and general biology, you know that the presence of a hydrogen bond explains the secondary structure of proteins, the structure of the DNA double helix, that is, the phenomenon of complementarity.

The concept of a chemical bond is of no small importance in various fields of chemistry as a science. This is due to the fact that it is with its help that individual atoms are able to combine into molecules, forming all kinds of substances, which, in turn, are the subject of chemical research.

The variety of atoms and molecules is associated with the emergence of various types of bonds between them. Different classes of molecules are characterized by their own characteristics of the distribution of electrons, and hence their own types of bonds.

Basic concepts

Chemical bond is called a set of interactions that lead to the binding of atoms with the formation of stable particles of a more complex structure (molecules, ions, radicals), as well as aggregates (crystals, glasses, etc.). The nature of these interactions is electrical in nature, and they arise during the distribution of valence electrons in approaching atoms.

Valence accepted name the ability of an atom to form a certain number of bonds with other atoms. In ionic compounds, the number of donated or attached electrons is taken as the valence value. In covalent compounds, it is equal to the number of common electron pairs.

Under the oxidation state is understood as a conditional the charge that could be on an atom if all polar covalent bonds were ionic.

The multiplicity of communication is called the number of shared electron pairs between the considered atoms.

The bonds considered in various branches of chemistry can be divided into two types of chemical bonds: those that lead to the formation of new substances (intramolecular) , and those that arise between molecules (intermolecular).

Basic communication characteristics

By the energy of communication is called the energy that is required to break all existing bonds in the molecule. It is also the energy released during the formation of a bond.

Communication length refers to the distance between adjacent nuclei of atoms in a molecule, at which the forces of attraction and repulsion are balanced.

These two characteristics of the chemical bond of atoms are a measure of its strength: the shorter the length and the greater the energy, the stronger the bond.

Valence angle it is customary to call the angle between the represented lines passing in the direction of the bond through the nuclei of atoms.

Relationship Description Methods

The most common two approaches to explaining the chemical bond, borrowed from quantum mechanics:

Molecular orbital method. He considers a molecule as a collection of electrons and nuclei of atoms, with each individual electron moving in the field of action of all other electrons and nuclei. The molecule has an orbital structure, and all of its electrons are distributed along these orbits. Also, this method is called MO LCAO, which stands for "molecular orbital - linear combination

Method of valence bonds. Represents a molecule as a system of two central molecular orbitals. Moreover, each of them corresponds to one bond between two adjacent atoms in the molecule. The method is based on the following provisions:

1. The formation of a chemical bond is carried out by a pair of electrons having opposite spins, which are located between the two considered atoms. The formed electron pair belongs to two atoms equally.
2. The number of bonds formed by one or another atom is equal to the number of unpaired electrons in the ground and excited states.
3. If electronic pairs do not take part in the formation of a bond, then they are called lone pairs.

Electronegativity

It is possible to determine the type of chemical bond in substances based on the difference in the values ​​of the electronegativities of its constituent atoms. Under electronegativity understand the ability of atoms to pull off common electron pairs (electron cloud), which leads to the polarization of the bond.

There are various ways to determine the values ​​of the electronegativities of chemical elements. However, the most used is the scale based on thermodynamic data, which was proposed back in 1932 by L. Pauling.

The more significant the difference in the electronegativities of atoms, the more its ionicity is manifested. On the contrary, equal or close values ​​of electronegativity indicate the covalent nature of the bond. In other words, it is possible mathematically to determine what kind of chemical bond is observed in a particular molecule. To do this, you need to calculate ΔХ - the difference between the electronegativities of atoms using the formula: ΔX = | X 1 -NS 2 |.

• If ΔX> 1.7, then the bond is ionic.
• If 0.5≤ΔX≤1.7, then the covalent bond is polar.
• If ΔX = 0 or close to it, then the bond refers to a covalent non-polar.

Ionic bond

An ionic bond is called such a bond that appears between ions or due to the complete pulling off of a common electron pair by one of the atoms. In substances, this type of chemical bond is carried out by the forces of electrostatic attraction.

Ions are charged particles formed from atoms as a result of the attachment or release of electrons. If an atom accepts electrons, it acquires a negative charge and becomes an anion. If the atom donates valence electrons, it becomes a positively charged particle called a cation.

It is characteristic of compounds formed by the interaction of atoms of typical metals with atoms of typical non-metals. The main part of this process is the desire of atoms to acquire stable electronic configurations. And typical metals and non-metals for this need to give or receive only 1-2 electrons, which they easily do.

The mechanism of the formation of an ionic chemical bond in a molecule is traditionally considered on the example of the interaction of sodium and chlorine. Alkali metal atoms easily donate an electron pulled by a halogen atom. The result is a Na + cation and a Cl - anion, which are held together by electrostatic attraction.

There is no ideal ionic bond. Even in such compounds, which are often referred to as ionic, the final transition of electrons from atom to atom does not occur. The formed electron pair still remains in common use. Therefore, one speaks of the degree of ionicity of the covalent bond.

Ionic bond is characterized by two main properties related to each other:

• nondirectionality, that is, the electric field around the ion has the shape of a sphere;
• unsaturation, that is, the number of oppositely charged ions that can be located around any ion, is determined by their size.

Covalent chemical bond

The bond formed when the electron clouds of nonmetal atoms overlap, that is, carried out by a common electron pair, is called a covalent bond. The number of shared pairs of electrons determines the multiplicity of the bond. Thus, hydrogen atoms are linked by a single H ··· H bond, and oxygen atoms form a double bond O :: O.

There are two mechanisms for its formation:

• Exchange - each atom represents one electron for the formation of a common pair: А
• Donor-acceptor - for the formation of a bond, one of the atoms (donor) provides a pair of electrons, and the second (acceptor) provides a free orbital for its placement: A +: B = A: B.

The methods of overlapping electron clouds during the formation of a covalent chemical bond are also different.

1. Direct. The cloud overlap region lies on a straight imaginary line connecting the nuclei of the atoms under consideration. In this case, σ-bonds are formed. The type of chemical bond that occurs in this case depends on the type of electron clouds undergoing overlapping: s-s, s-p, p-p, s-d or p-d σ-bonds. In a particle (molecule or ion), only one σ-bond is possible between two neighboring atoms.
2. Lateral. It is carried out on both sides of the line connecting the atomic nuclei. This is how a π-bond is formed, and its varieties are also possible: p-p, p-d, d-d. Apart from the σ-bond, the π-bond is never formed; it can be in molecules containing multiple (double and triple) bonds.

Covalent bond properties

It is they who determine the chemical and physical characteristics of the compounds. The main properties of any chemical bond in substances are its directionality, polarity and polarizability, as well as saturation.

Focus connection is due to the peculiarities of the molecular structure of substances and the geometric shape of their molecules. Its essence is that the best overlap of electron clouds is possible with a certain orientation in space. Above, the options for the formation of σ- and π-bonds have already been considered.

Under saturation understand the ability of atoms to form a certain number of chemical bonds in a molecule. The number of covalent bonds for each atom is limited by the number of outer orbitals.

Polarity bond depends on the difference in the values ​​of electronegativities of atoms. The uniformity of the distribution of electrons between the nuclei of atoms depends on it. A covalent bond for this trait can be polar or non-polar.

• If the common electron pair equally belongs to each of the atoms and is located at the same distance from their nuclei, then the covalent bond is non-polar.
• If the common pair of electrons is displaced to the nucleus of one of the atoms, then a covalent polar chemical bond is formed.

Polarizability is expressed by the displacement of bond electrons under the action of an external electric field, which can belong to another particle, neighboring bonds in the same molecule, or come from external sources of electromagnetic fields. So, a covalent bond under their influence can change its polarity.

Hybridization of orbitals is understood as a change in their shape during the implementation of a chemical bond. This is necessary to achieve the most effective overlap. There are the following types of hybridization:

• sp 3. One s and three p orbitals form four "hybrid" orbitals of the same shape. Outwardly, it resembles a tetrahedron with an angle between the axes of 109 °.
• sp 2. One s- and two p-orbitals form a flat triangle with an angle between the axes of 120 °.
• sp. One s- and one p-orbital form two "hybrid" orbitals with an angle between their axes of 180 °.

A feature of the structure of metal atoms is a rather large radius and the presence of a small number of electrons in outer orbitals. As a result, in such chemical elements, the bond between the nucleus and the valence electrons is relatively weak and easily broken.

Metal a bond is called such an interaction between atoms-ions of metals, which is carried out with the help of delocalized electrons.

In metal particles, valence electrons can easily leave the outer orbitals, as well as occupy vacant places on them. Thus, at different times the same particle can be an atom and an ion. The electrons detached from them move freely throughout the volume of the crystal lattice and carry out a chemical bond.

This type of bond has similarities to ionic and covalent. As for the ionic bond, ions are required for the existence of a metallic bond. But if for the implementation of electrostatic interaction in the first case, cations and anions are needed, then in the second the role of negatively charged particles is played by electrons. If we compare a metallic bond with a covalent bond, then common electrons are required for the formation of both. However, unlike a polar chemical bond, they are not localized between two atoms, but belong to all metal particles in the crystal lattice.

The special properties of almost all metals are due to the metal bond:

• plasticity, is present due to the possibility of displacement of layers of atoms in the crystal lattice, held by the electron gas;
• metallic luster, which is observed due to the reflection of light rays from electrons (in a powdery state there is no crystal lattice and, therefore, electrons moving along it);
• electrical conductivity, which is carried out by a flow of charged particles, and in this case, small electrons move freely among large metal ions;
• thermal conductivity is observed due to the ability of electrons to transfer heat.

This type of chemical bond is sometimes referred to as an intermediate between covalent and intermolecular interactions. If a hydrogen atom has a bond with one of the strongly electronegative elements (such as phosphorus, oxygen, chlorine, nitrogen), then it is able to form an additional bond called hydrogen.

It is much weaker than all the types of bonds considered above (energy not exceeding 40 kJ / mol), but it cannot be neglected. That is why the hydrogen chemical bond in the diagram looks like a dotted line.

The formation of a hydrogen bond is possible due to the simultaneous donor-acceptor electrostatic interaction. A large difference in the values ​​of electronegativity leads to the appearance of excess electron density on the atoms of O, N, F and others, as well as to its lack on the hydrogen atom. In the event that there is no existing chemical bond between such atoms, when they are sufficiently close, the forces of attraction are activated. In this case, the proton is the acceptor of the electron pair, and the second atom is the donor.

A hydrogen bond can arise both between adjacent molecules, for example, water, carboxylic acids, alcohols, ammonia, and within a molecule, for example, salicylic acid.

The presence of a hydrogen bond between water molecules explains a number of its unique physical properties:

• The values ​​of its heat capacity, dielectric constant, boiling and melting points, in accordance with the calculations, should be significantly less than the real ones, which is explained by the connectedness of molecules and the need to spend energy on breaking intermolecular hydrogen bonds.
• Unlike other substances, the volume of water increases with decreasing temperature. This is due to the fact that the molecules occupy a certain position in the crystal structure of ice and move away from each other by the length of the hydrogen bond.

This bond plays a special role for living organisms, since its special structure, and hence properties, are determined by its presence in protein molecules. In addition, nucleic acids, making up the double helix of DNA, are also linked by hydrogen bonds.

Crystal bonds

The overwhelming majority of solids have a crystal lattice - a special mutual arrangement of the particles that form them. In this case, a three-dimensional periodicity is observed, and atoms, molecules or ions are located at the nodes, which are connected by imaginary lines. Depending on the nature of these particles and the bonds between them, all crystal structures are divided into atomic, molecular, ionic and metallic.

The sites of the ionic crystal lattice are cations and anions. Moreover, each of them is surrounded by a strictly defined number of ions with only opposite charges. A typical example is sodium chloride (NaCl). They tend to have high melting points and hardness as they require a lot of energy to break down.

At the sites of the molecular crystal lattice are molecules of substances formed by a covalent bond (for example, I 2). They are connected with each other by a weak van der Waals interaction, and therefore, such a structure is easy to destroy. Such compounds have low boiling and melting points.

The atomic crystal lattice is formed by the atoms of chemical elements with high valence values. They are connected by strong covalent bonds, which means that substances are distinguished by high boiling points, melting points and great hardness. An example is a diamond.

Thus, all types of bonds present in chemical substances have their own characteristics, which explain the subtleties of the interaction of particles in molecules and substances. The properties of the connections depend on them. They determine all the processes occurring in the environment.

Chemical bond, its types, properties, along with is one of the cornerstones of an interesting science called chemistry. In this article, we will analyze all aspects of chemical bonds, their significance in science, give examples and much more.

What is chemical bond

In chemistry, a chemical bond is understood as the mutual adhesion of atoms in a molecule and, as a result of the action of the force of attraction that exists between. It is thanks to chemical bonds that various chemical compounds are formed, this is the nature of the chemical bond.

Types of chemical bonds

The mechanism of formation of a chemical bond strongly depends on its type or type; in general, the following main types of chemical bonds differ:

• Covalent chemical bond (which in turn can be polar and non-polar)
• Ionic bond
• connection
• Chemical bond

like people.

As for, a separate article is devoted to it on our website, and you can read in more detail at the link. Further, we will analyze in more detail all the other main types of chemical bonds.

Ionic chemical bond

The formation of an ionic chemical bond occurs when two ions with different charges are mutually attracted by electricity. Ions are usually simple with such chemical bonds, consisting of one atom of matter.

Ionic chemical bond diagram.

A characteristic feature of the ionic type of a chemical bond is its lack of saturation, and as a result, a very different number of oppositely charged ions can join an ion or even a whole group of ions. An example of an ionic chemical bond is the cesium fluoride compound CsF, in which the “ionicity” level is almost 97%.

Hydrogen chemical bond

Long before the appearance of the modern theory of chemical bonds in its modern form, chemical scientists noticed that hydrogen compounds with non-metals have various amazing properties. Let's say the boiling point of water and together with hydrogen fluoride is much higher than it could be, here's a ready-made example of a hydrogen chemical bond.

The picture shows a diagram of the formation of a hydrogen chemical bond.

The nature and properties of the hydrogen chemical bond are due to the ability of the hydrogen atom H to form another chemical bond, hence the name of this bond. The reason for the formation of such a connection is the properties of electrostatic forces. For example, the general electron cloud in a hydrogen fluoride molecule is so displaced towards fluorine that the space around the atom of this substance is saturated with a negative electric field. Around the hydrogen atom, especially when it is deprived of its only electron, everything is exactly the opposite, its electron field is much weaker and, as a result, has a positive charge. And positive and negative charges, as you know, are attracted, in such a simple way and there is a hydrogen bond.

Chemical bond of metals

What chemical bond is typical for metals? These substances have their own type of chemical bond - the atoms of all metals are arranged not just like that, but in a certain way, the order of their arrangement is called the crystal lattice. The electrons of different atoms form a common electron cloud, while they weakly interact with each other.

This is what a metallic chemical bond looks like.

Any metals can be used as an example of a metallic chemical bond: sodium, iron, zinc, and so on.

How to determine the type of chemical bond

Depending on the substances taking part in it, if a metal and a non-metal, then the bond is ionic, if two metals, then metallic, if two non-metals, then covalent.

Chemical bond properties

To compare different chemical reactions, different quantitative characteristics are used, such as:

• length,
• energy,
• polarity,
• order of links.

Let's take a closer look at them.

Bond length - the equilibrium distance between the nuclei of atoms, which are connected by a chemical bond. Usually measured experimentally.

The energy of a chemical bond determines its strength. In this case, energy refers to the effort required to break a chemical bond and separate atoms.

The polarity of a chemical bond shows how much the electron density is shifted towards one of the atoms. The ability of atoms to shift electron density to themselves, or in simple terms, "pull the blanket over themselves" in chemistry is called electronegativity.

All chemical compounds are formed through the formation of a chemical bond. And depending on the type of connecting particles, several types are distinguished. The most basic- it is covalent polar, covalent non-polar, metallic and ionic. Today we will talk about ionic.

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What are ions

It is formed between two atoms - as a rule, provided that the difference in electronegativity between them is very large. The electronegativity of atoms and ions is assessed using the Polling scale.

Therefore, in order to correctly consider the characteristics of compounds, the concept of ionicity was introduced. This characteristic allows you to determine the percentage of a particular bond is exactly ionic.

The compound with the highest ionicity is cesium fluoride, in which it is approximately 97%. Ionic bond is characteristic for substances formed by metal atoms located in the first and second groups of D.I. Mendeleev, and atoms of non-metals, which are in the sixth and seventh groups of the same table.

Note! It should be noted that there is no compound in which the relationship is exclusively ionic. For the currently discovered elements, one cannot achieve such a large difference in electronegativity to obtain a 100% ionic compound. Therefore, the definition of the ionic bond is not entirely correct, since compounds with partial ionic interaction are actually considered.

Why did they introduce this term, if in reality such a phenomenon does not exist? The fact is that this approach helped to explain many of the nuances in the properties of salts, oxides and other substances. For example, why are they highly soluble in water, and their solutions are capable of conducting electric current... This cannot be explained from any other point of view.

Formation mechanism

The formation of an ionic bond is possible only if two conditions are met: if the metal atom participating in the reaction is able to easily donate electrons that are at the last energy level, and the non-metal atom is able to accept these electrons. Metal atoms are by nature reducing agents, that is, they are capable of donation of electrons.

This is due to the fact that at the last energy level in a metal there can be from one to three electrons, and the radius of the particle itself is quite large. Therefore, the force of interaction of the nucleus with electrons at the last level is so small that they can easily leave it. With non-metals, the situation is completely different. They have small radius, and the number of its own electrons at the last level can be from three to seven.

And the interaction between them and the positive nucleus is strong enough, but any atom strives to complete the energy level, so the atoms of the non-metal strive to get the missing electrons.

And when two atoms - a metal and a non-metal - meet, electrons move from a metal atom to a non-metal atom, and a chemical interaction is formed.

Connection diagram

The figure clearly shows how the formation of the ionic bond is carried out. Initially, there are neutrally charged sodium and chlorine atoms.

The first has one electron at the last energy level, the second seven. Next, an electron transition from sodium to chlorine and the formation of two ions. Which combine with each other to form a substance. What is an ion? Ion is a charged particle in which the number of protons is not equal to the number of electrons.

Differences from covalent type

The ionic bond has no direction due to its specificity. This is due to the fact that the electric field of an ion is a sphere, while it decreases or increases in one direction uniformly, obeying the same law.

Unlike covalent, which is formed by overlapping electron clouds.

The second difference is that the covalent bond is saturated... What does it mean? The number of electronic clouds that can take part in the interaction is limited.

And in the ionic field, due to the fact that the electric field has a spherical shape, it can combine with an unlimited number of ions. This means that we can say that it is not saturated.

It can also be characterized by several more properties:

1. Bond energy is a quantitative characteristic, and it depends on the amount of energy that needs to be spent on breaking it. It depends on two criteria - bond length and ion charge participating in her education. The bond is the stronger, the shorter its length and the greater the charges of the ions that form it.
2. Length - this criterion has already been mentioned in the previous paragraph. It depends solely on the radius of the particles participating in the formation of the compound. The radius of the atoms changes as follows: decreases over the period with increasing serial number and increases in the group.

Substances with ionic bonds

It is characteristic of a significant number of chemical compounds. This is most of all salts, including the well-known table salt. It is found in all connections where there is a direct contact between metal and non-metal... Here are some examples of ionically bonded substances:

• sodium and potassium chlorides,
• cesium fluoride,
• magnesium oxide.

It can also manifest itself in complex connections.

For example magnesium sulfate.

Here is the formula for a substance with an ionic and covalent bond:

An ionic bond will form between the oxygen and magnesium ions, but sulfur and are already connected to each other using a covalent polar one.

From which we can conclude that ionic bonds are characteristic of complex chemical compounds.

What is ionic bond in chemistry

Types of chemical bonds - ionic, covalent, metallic

Output

Properties are directly device dependent crystal lattice... Therefore, all compounds with an ionic bond are readily soluble in water and other polar solvents, are conductive, and are dielectrics. At the same time, they are rather refractory and fragile. The properties of these substances are often used in the design of electrical devices.