Chemical bonds correspond to the union of atoms for the formation of molecules . In other words, chemical bonds happen when atoms react with each other.
They are classified as: ionic bond, covalent bond, dative covalent bond and metallic bond.
In the Octet Theory, created by Gilbert Newton Lewis (1875-1946), American chemist and Walter Kossel (1888-1956), German physicist, emerged from the observation of some noble gases and some characteristics such as the stability of these elements. filled by 8 electrons in the Valencia layer .
From this, the "Octet Theory or Rule" postulates that an atom acquires stability when it has 8 electrons in the valence shell (outermost electron shell), or 2 electrons when it has only one shell.
To this end, the atom seeks its stability by donating or sharing electrons with other atoms, from which chemical bonds arise.
Also called electrovalent bonding , this type of bonding is performed between ions (cations and anions), hence the term " ionic bonding ".
Ions are atoms that have an electric charge by the addition or loss of one or more electrons, so a negatively charged anion joins with a positively charged cation forming an ionic compound through the electrostatic interaction between them.
Example : Na + Cl - = NaCl (sodium chloride or table salt)
Also called molecular bonding , covalent bonds are bonds in which electron sharing occurs to form stable molecules, according to the Octet Theory; unlike ionic bonds where there is electron loss or gain.
In addition, electronic pairs is the name given to the electrons given by each nucleus, figuring the electron sharing of covalent bonds.
As an example, look at the water molecule H2O: H - O - H , formed by two hydrogen and one oxygen atoms where each trace corresponds to a shared electron pair forming a neutral molecule, since there is no loss or gain. of electrons in this kind of bond.
Also called coordinate bonding , the dative covalent bond is similar to the dative bond, but it occurs when one of the atoms has its full octet, that is, eight electrons in the last shell and the other, to complete its electronic stability needs to acquire two more electrons.
Represented by an arrow an example of this type of bond is the sulfur dioxide compound SO2: O = S → O
This is because a double bond of sulfur with one of the oxygen is established to achieve its electronic stability, and in addition, the sulfur donates one pair of its electrons to the other oxygen so that it has eight electrons in its shell. valence .
It is the bond that occurs between metals, elements considered electropositive and good thermal and electrical conductors. To this end, some metals lose electrons from their last shell called "free electrons" thus forming cations.
From this, the electrons released at the metal bond form an "electronic cloud", also called the "sea of electrons" that produces a force that causes the metal atoms to remain united. Examples of metals: Gold (Au), Copper (Cu), Silver (Ag), Iron (Fe), Nickel (Ni), Aluminum (Al), Lead (Pb), Zinc (Zn), among others.