Valence Electrons

The electrons in valence shells are called valence electrons. Electrons close to the center of the atom are called core electrons. When atoms combine, they form molecules. Valence electrons end up on the outside of a molecule.

Till now, we have been talking about electrons simply as negative charges which are present inside the atom. However, these negative charges have a positive counterpart, called protons, which are located inside the nucleus of an atom. The number of protons is equal to the number of electrons present outside the nucleus in an atom. Electrons are present outside the nucleus because they have less mass than protons and hence, they can move more easily than protons. Protons and neutrons together make up nuclei while electrons make up clouds around them.

Both protons and neutrons are responsible for giving each element their unique properties such as their mass and charge respectively. Both these particles hold an equal number of positive charges or nuclear charges. However, protons have a positive charge (+) while neutrons do not carry charge at all.

Meaning of Valence Electrons

Valence is an important concept in chemistry and has a different meaning in other theories of bonding. In chemistry, when you look at the periodic table of elements, you will find that at the top of each column, there is a number. That number is that element’s valence. The symbol for valence is “Val”.

Valence is not the same thing as bond order. Bond order refers to the number of bonds between atoms, while valence refers to the number of electrons an atom needs in its outermost shell to be stable (i.e., to have a noble gas configuration). It is necessary to know both bond order and valence to determine the structure of a molecule.

An atom’s valence electrons are in the outermost shell of its electrons. The number of valence electrons is determined by the number of protons in its nucleus. Hydrogen has one proton and one electron, so it has a single valence electron. Helium has two protons and two electrons, so it has two valence electrons. The most common valences are 2 and 8.

Importance of Valence Electrons

The valence electrons are part of the outermost electron shells of an atom. These electrons have more energy and weight than those present in the inner orbits. This means that these electrons are usually involved in most of the chemical reactions because they contain more energy compared to the electrons in the inner orbits. Meanwhile, the number of valence electrons present also helps us determine a specific element’s chemical properties, such as its valence or valency, formation of bonds with other elements, and so on. It also gives us an idea of how readily atoms can form bonds, how many unpaired electrons it has, and so on.

For example, an atom with six valence electrons is expected to form a bond with one atom that has only two valence electrons. This is because both atoms will get rid of their extra electrons after combining with each other to form H2 which is a water molecule. Meanwhile, an atom that has four valence electrons will combine with another atom that also has four valence electrons since both atoms need to get rid of their extra electrons. The result is O2 which is a molecule made up of two oxygen atoms.

Characteristics of Valence Electrons

Electrons are the basic units of an atom. They are present in all atoms except inert gasses. They occupy the orbitals of the atom which is around the nucleus. The number of valence electrons of an atom can easily be obtained from the periodic table because it is equal to the group number of the atom. Atoms are most stable if they are having a filled valence shell of electrons. Atoms transfer or share electrons in such a way that they can attain a filled shell of electrons.

In bonds with covalent character, the electrons are not shared equally by the nuclei but are arranged tetrahedrally around both nuclei according to VSEPR Theory. It is easy to remember this by using Lewis Dot Diagrams in which oxygen always has two dots as it forms two bonds with two other atoms while nitrogen/carbon has three dots since they form three bonds with three other atoms.

The characteristics of Valence Electrons are-

• Only the outermost group valence electrons are present for the main group of the periodic elements.
• There are chances that the inner shell valence electron exists in case the metal is of transition type.
• All the atoms which would be having a closed shell mean that those atoms would be chemically inert.
• The valence electron has the capability of releasing or absorbing energy in the form of photons.

Determination of Valence Electrons

In the periodic table, there are horizontal rows of elements called periods. The elements in a period all have the same number of protons. Then the elements are organised into vertical columns called groups. Each element in a group has the same number of valence electrons, which is given in the table as their group number. The outermost shell or level of electrons is called the valence shell and it holds up to 8 electrons for each element but only 2 for helium.

To find the valence electrons of an element, it is necessary to first understand what valence electrons are and what elements have them. In this way, we will be able to find the valence of all elements. Valence electrons are the outermost and least tightly bound electrons in an atom. These are the electrons that are usually involved in chemical reactions and can become transferred from atom to atom.

Conclusion

In this material, we discussed the concept of valence electrons along with some examples to make the concept more clear. We also discussed how to determine it through the periodic table and also other things.