What are valence electrons? – Function and characteristics of these electrons
The structure of matter is made up of atoms. They are the least amount of a chemical element that has its own existence and can enter into combination. They are made up of a nucleus of protons (positive), neutrons (no charge) and a shell of electrons (negative). They occupy the sublevels according to the increasing order of their energy, which in general increases with the main quantum number, with some exceptions. Often, they completely fill one sublevel before they begin to occupy the next. For this reason, the salient aspects of them and their characteristics will be exposed.
Definition of Valence Electrons
The atom in its structure presents a negatively charged particle called an electron. It was discovered by Joseph John Thomson on April 30, 1897. These are distributed around the nucleus, according to their degree of energy. Therefore, electrons are defined as those that are located in the atom in the upper energy level or in its last layer. It is also known by the name of the outer layer according to the atomic model proposed by Bohr. They are responsible for the characteristics of chemical elements. They are represented by the Lewis structure.
Furthermore, if the atomic number (Z) is known and can be determine the valence electrons. As an example, we have sodium (Na) has a Z=11, which means that it has 11 electrons in three shells (2.8 and 1). As shown by 1s2 2s2 2p6 3s1. Observing the electronic configuration, sodium has a valence electron in its last shell.
The energy levels refer to the different electronic layers that surround the nucleus of an atom. Each energy level is composed of sublevels that are differentiated by the amount of energy that the electrons occupying them have. The electrons in an atom are organized into specific energy levels and sublevels, which determine the chemical and physical properties of the atom.
What are valence electrons used for?
They are used to form new compounds. Through chemical bonds attached with other elements and are capable of being constituted. Which can be ionic, covalent and metallic bonds. They are fundamental in the conduction of electric current, in those materials that are semiconductors.
Allows the classification of elements as conductors, insulators or semiconductors. Likewise, electronegativity, which is the ability of an atom to attract electrons by joining through a chemical connection. In the year 1932, Linus Pauling was the one who established the magnitude of this, developing the theory of the valence bond. It is not measured directly, like ionization energy. It can only be found by performing calculations using other properties.
These are important because they are involved in chemical reactions, gaining or losing electrons to fill the octet in your last energy level. They are of vital importance because they collaborate in the formation of molecules and compounds. Also, in the area of chemistry they allow to determine the number of valence electrons in a specific particle and thus identify its bond.
In addition, according to the physical-chemical properties of the number of atoms that make it up, they can be ordered the elements on the periodic table, knowing its atomic number. In this, the chemical elements are organized in seven periods (horizontal) and in 18 groups (vertical). Valence electrons allow us to know:
- Confirm writing a chemical formula or if it is a radical; in case it is incorrect, it is because when adding the amount of the elements and the electrons it is not zero.
- When a new compound is formed, detect the times a radical is found or an element.
- Know the valence with which you are operating, since they are extremely reactive and valence is identified as the radical works.
- So too, are used in hybridizations and quantum numbers.
Why are valence electrons important?
They are essential since, thanks to them, more than a hundred chemical elements, their properties and possible combinations to form various compounds are known today. In other respects, the colors, because the materials have the ability to assimilate light. It is made up of photons that have an energy that corresponds to the energy jumps of the electrons. Therefore, light is not absorbed, but rather reflected, generating the colors that are perceived by the human eye.
In addition, they are involved in all the chemical processes that cause life. They are the basis of microelectronics and digital technology due to the properties of electrons. Are able to walk electrical circuits that are part of household appliances, which are used in daily life.
How do valence electrons work?
Valence electrons work in a chemical reaction when they are transferred from one atom to another. Changing the electronic structure and when they join compounds through chemical bonds. Therefore, the valence of any element clearly intervenes in the ability to unite with others and create chemical compounds.
What is kernel?
It is a way of writing the electronic configuration of any element in a simplified way. To better understand this term used in inorganic chemistry. It is necessary to understand that the simplest way to describe the arrangement of electrons in an atom is to give its electronic configuration. It tells us the number of electrons in each main level and in each sublevel.
- For example: The electronic configuration of Magnesium (Z=12) is 1s2 2s2 2p6 3s2
To write this same electronic configuration, the Kernel is used for short, which means that it is expressed in a more simplified or reduced form. Start counting electrons applying as reference to the noble gas, closest to the element of which one wants to write the electronic configuration.
Considering the previous example of Magnesium(Z=12).
- The electronic configuration of Neon (Ne) is 1s2 2s2 2p6 and that of Magnesium is 1s2 2s2 2p6 3s2, which are initially equal, therefore its Kernel is summarized as follows: (Ne) 3s2.
- In the case of Oxygen whose Z= 8, the Kernel would be (He) 1s2 2s2 2p4
According to what was mentioned before, the Kernel is conceived as that included in another, that is, it represents the electronic configuration of a gas within that of an element that you want to know. Starting from the noble gases, who must have the atomic number (Z) less than that of the element. The chemical symbol for the noble gas in brackets ( ).
To easily write the electronic configuration through the kernel, one must use the Aufbau principle, which means “build”. It states that electrons complete atomic orbitals of less energy before filling those of greater energy and the use of the periodic table.
Here we provide you some examples how the term ‘kernel’ might be used in chemistry:
- The kernel of the carbon atom has a mass number of 12, which means that it is made up of 6 protons and 6 neutrons.
- Hydrogenation catalysts used in the chemical industry often contain a palladium kernel, which It is a metal that is very effective to catalyze the hydrogenation reaction of organic molecules.
- In the synthesis of ammonia from nitrogen and hydrogen, a catalyst is used that contains an iron kernel. The iron kernel allows the reaction to proceed faster and with lower energy consumption.
- Elements in group 18 of the periodic table, which include helium, neon, argon, and other noble gases, have a very stable kernel because they have a full number of electrons in its valence shell. This gives them high chemical stability and low reactivity.
To conclude, it is necessary to know that atoms have to unite forming molecules and must make chemical bonds in which the orbitals and the electrons that are in them intervene.