Types of Chemical Bonds

Chemistry / by admin / July 04, 2021

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When two or more atoms form a molecule, they join together by means of a junction between electrons of its last layers, the most superficial. This union is called Chemical bond. For a chemical bond to form, the atoms must have their incomplete octet, that is, less than eight electrons in their last shell, which is the number that will give them chemical stability.

There are three types of chemical bonds:

Ionic bonds
Covalent bonds
Metal links

Ionic bonds

Ionic bonds are those in which the valence electrons are attracted by electrostatic forces. The atom (s) that have 1 to 4 valence electrons can deliver them to form the bond; This gives it a positive charge, because it would be getting rid of the negative charges. On the other hand, the atom (s) with 5 to 7 valence electrons will be able to receive those necessary to reach 8.

This gives them a negative charge, because they pick up electrons, which are negative. The fact that electrons can be captured or delivered gives the atoms the electrical charge

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. According to Coulomb's law, the charges formed on both atoms they are going to attract each other with a force, which is the electrostatics mentioned above. Negative charges attract positive charges and vice versa. Opposite charges attract. Once this force binds them together, the molecule is formed.

Ionic bonds occur mostly between metal and nonmetal atoms. Metals give up their electrons and always carry a positive charge, participating as a cation (+). Nonmetals are electron receptors and generally carry a negative charge, participate as anions (-) but it also happens that they carry a positive charge, this when they form groups of charged atoms called radicals, as ammonium NH₄⁺, carbonate CO₃^-2, phosphate PO₄^-3.

Among the chemical compounds that are formed by ionic bonds are:

Binary salts
Oxisales

When these substances are dissolved in water they dissociate, namely, separate into their electrical charges and these are dispersed in the water together with the hydrogen ions H⁺ and hydroxyl (OH^-) that form water. The mixture that forms is a solution called electrolyte.

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Covalent bonds

Covalent bonds are those in which electrons are shared without detaching them from the atom, that is, without the formation of electrical charges. The atoms are held together by proximity and use the force with which the nucleus attracts electrons. Once the bond is formed, the two or more nuclei of the atoms end up attracting the shared electrons, thereby fulfilling the octet rule and making the molecule stable.

There are several forms of covalent bonding, and they are:

Covalent bond
Coordinate covalent bond
Polar covalent bond
Nonpolar covalent bond

The covalent bond It is just like the one described at the beginning. The participating atoms share electrons so that they all have their complete octet. There are no electrical charges here, because no electrons are shed, they are just shared.

In the coordinate covalent bond it is only one atom that contributes all the electrons necessary for the bond. The other atom simply binds together and takes these electrons as its own. The molecule is formed like this. This is the case, for example, of sulfuric acid H₂SW₄ in which sulfur shares two pairs of electrons with oxygen atoms.

In the polar covalent bond, the forces between the atoms are tilted to one side of the molecule. This when there are different types of atoms in the molecule. This force is measured in Debye units, and the higher its value on one side of the molecule, the more polar it will be. This means that poles are formed in the structure, and that is why they are given this name. Its forces are asymmetric.

In the nonpolar covalent bond, the forces between the atoms are uniform throughout the entire molecule, and therefore no poles are formed in its structure. It works as a single unit and that is why it is very difficult, almost impossible, to divide its loads. This makes it insoluble in water. This is the case of compounds such as alkanes, which have their equal forces throughout the molecule. Its forces are symmetrical.

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Metallic bond

The atoms of a metal are held together by means of metallic bonds. In this type of bond, the electrons of all the atoms are attracted to form a crystalline lattice that remains firm. The bonds of the crystal lattice have all electrons interspersed and arranged to carry electrical current and heat when it is transmitted to them. In transition metals this structure of metallic bonds is more remarkable, because their atoms are larger.