Since the human being is aware of his intellect, he has taken more and more interest in analyzing and understanding everything that surrounds him, phenomena that are now fully known, such as the process of evaporation of water and other more complex ones, such as the elaboration of composite materials, have passed from simple hypotheses to confirmed theories.
We are surrounded by processed materials that we see daily in each of the objects we use throughout our lives, which man has explained with the creation of concepts such as “Dalton’s Atomic Theory”, “Thomson’s Atomic Model” and ” The Bohr Atomic Model” among others, and that lead us to our point to deal with, which is The Octet Rule.
What do you need
First of all we will need:
- Paper.
- Pencil.
- Draft.
- Periodic Table of Chemical Elements.
- A little book of basic chemistry.
- And above all, a very broad mind to make it easier for us to understand the subject.
Instructions
It is necessary to review some concepts before delving into the Octet Rule.
- Dalton’s Atomic Theory: this theory is based on the following postulates: the elements are made up of atoms in separate and indestructible particles. The atoms of an element are equal in mass and in all characteristics. Atoms of different elements are different from each other. The union of the atoms of other elements gives way to the formation of new chemical compounds with their respective qualities and characteristics. These postulates were published by chemist John Dalton between the years 1803 and 1808.
- Thomson’s Atomic Model: this model states that the atom is a sphere with a properly positive charge, in which the electrons are embedded. This atomic model is also known as the Raisin Pudding Model because of its visual resemblance to the explanation Thomson put forward. Precisely the doubts about the distribution of positive charges in the atom ended up making the use of this model obsolete, but it was very useful, raised by Joseph John Thomson in 1904 and discarded in 1911.
- Bohr’s Atomic Model: defines that the electron rotates at a fixed distance from the nucleus of the atom, these electrons when changing orbit absorb or release energy, these present orbits are called layers of the atom, where the electron being at a longer length Closer to the nucleus it will present a lower amount of energy and when it moves away a greater amount. Niels Bohr published his model in 1913 and served as the basis for the theories raised later.
- The atom: commonly defined as the smallest particle in the universe and which forms a mass, is made up of a nucleus with positively charged particles (protons) and also particles with neutral charges (Neutrons). And in its external part (crust) provided with negatively charged particles called Electrons.
- Layers of the atom: called Electron Layers are a series of levels where electrons travel that surround the nucleus of the atom, these layers in each of their levels can contain a maximum number of electrons that must be filled before moving on to the next level. The first shell (K) n=1 can have a maximum of 2 electrons, the second shell (L) n=2 a maximum of 8 electrons, the third shell (M) n=3 a maximum of 18 electrons, the fourth shell (N ) n=4 a maximum of 32 electrons, the fifth shell (O) n=5 a maximum of 32 electrons, the sixth shell (P) n=6 a maximum of 18 electrons and the seventh shell (Q) n=7 a maximum of 8 electrons.
- Valence layer: It is the last layer of the atom (outer layer) that determines the ability to produce chemical reactions with another atom by exchanging electrons. The number of electrons existing in this outer shell will define the valence number, oxidation number of this atom.
- Periodic table of the chemical elements: The periodic table is a visual representation of how the different chemical elements studied by man are classified and ordered, for this they are located in columns (groups) and rows (periods) having the particularity that the elements presented in the same column have similar characteristics and behaviors and with a total of 18 groups. Among the most prominent groups are that of Noble Gases, Metals, Non-Metals, Halogens, Alkalines, etc. In it you can locate the elements according to their symbol, name, atomic mass and atomic number, being a fundamental tool for the study of chemistry. The first periodic table was presented with 63 chemical components in 1869 by Dimitri Mendeleev increased through the years to a number of 118 today.
- Chemical links: The union of two or more chemical elements gives way to a compound, which is why the need to explain how the interaction between atoms is carried out. In the Ionic bond one or several electrons are transferred to another atom, understanding that there is an attraction between negatively charged ions and positively charged ions. The Covalent bond is formed when two or more atoms share one or more electrons in their Valencian shell, an example of this is the Chlorine (Cl2) molecule, which is the result of the union of two chlorine atoms (Cl + Cl). There are 2 types of Covalent bond, the Polar that is made between 2 different atoms (water, alcohol, methanol) and the Apolar that occurs between 2 equal atoms (hydrogen, oxygen, sulfur). In Metallic Bonds the interaction does not occur between two or more atoms, if not between a cation and the free electrons present, which translates into a solid structure with thermal and electrical conductivity capacities. Also less commented but existing, are the chemical bonds between molecules such as those by Van der Waals forces and by Hydrogen Bond.
- Lewis diagram: It is the graphical representation where the electrons of the valence shell are shown marked with dots around the symbol of the chemical element, these electrons can be presented in pairs or singles and the bond with other atoms is represented with simple lines, doubles and triples where each of these lines represents a pair of electrons.
- Noble Gases: They are located in column 18 of the periodic table, characterized by being chemically stable elements that do not react with any other, having an inert behavior under normal conditions. Their reputation as stable gases is due to the fact that they have a complete Valencian Shell in their amount of electrons. The gases that make up this group are Neon (Ne), Helium (He), Argon (Ar), Xenon (Xe), Krypton (kr), Radon (Rn) and Organeson (Og). The most common use for this type of element is in the refrigeration area. The study of these gases led to the creation of the Octet Rule.
- The Octet Rule: this rule tells us that the chemical elements, in order to stabilize their properties, tend to configure themselves in such a way that they fill their last energy level (Valencian layer) with 8 electrons, so they are close to the most immediate noble gas when seen in the periodic table. All the noble gases (except Helium (He)) have the particularity of having 8 electrons in their last shell and from there comes their peculiarity of maintaining their chemical and physical properties under normal conditions. It is also indicated that the properties and behavior of the combined compounds will depend directly on the type of bond and number of bonds between the 2 or more atoms in combination. There are compounds that do not comply with the octet rule such as Nitrogen (N), Oxygen (O), Fluorine (F), Sulfur (S), Boron (B), Hydrogen (H), These elements have the ability to receive more than 8 electrons in their valence shell, which is known as hypervalence. The Octet Rule was postulated by the American Gilbert Newton Lewis in 1917 and denotes in other words that the atoms that comply with it fill their “S” and “P” subshells with electrons and also that it is the visualization of four pairs of electrons around the atom.
All these theories, concepts and postulates are the result of hundreds of investigations carried out for more than 200 years in which it has gradually evolved in order to create a definition that satisfies all the unknowns and doubts that inevitably arise in its development. Each theory, no matter how old or obsolete it is today, served at the time to take a step to the next.
The continuous advances in the field of chemistry have been essential for the development of other areas of industry that are so important to life, such as the pharmaceutical industry and electronics, practically many of the things that seem common to us today until a few years ago. 30, 40 years were even unthinkable but they are largely based on studies dating back more than a century and highly analyzed
Tips
- To clearly understand everything related to the Octet Rule, the basic concepts about the atom must be reviewed, how it is formed, how it interacts with other atoms of the same or different elements and what are its layers and subshells, the number of maximum electrons capacity to receive or contribute electrons, as an initial step.
- Knowing and manipulating the periodic table of chemical elements will also be very useful since from here we will quickly and easily obtain the necessary data to know the atomic structure of the elements.
- Understanding the concept and development of the Lewis Diagram will allow us to advance to the Octet Rule because it is a result of the concept of the diagram.
- Study and detail the characteristics of the noble gases in terms of their electrons in their last orbit shell, because these are the direct example of the definition of the rule and remember that all chemical elements tend to approach these gases by gaining or losing electrons.
- Leaning on video tutorials where the exchange of electrons between atoms is explained through exercises, the distribution of these in the layers and sublayers, the creation of single, double and triple bonds between atoms will also be of great help.
- In general, many of the literatures that you can find on the web can help you understand the subject, with more or less words they can all guide you on this matter. Remember, it will be easier for you even if you are not knowledgeable about the subject, to start from simple definitions as you understand and advance in the concepts, just as we did in this article, where one definition leads directly to the other to complete a whole.
If you like science, knowing the Octet rule will be very useful to advance your knowledge.