How to Find Valence Electrons

Valence electrons are situated at the outermost highest energy level of an atom, making them the most available for creating molecular bonds. The number of valence electrons in one atom of any element is determined by its position in the periodic table. The valence electrons are the primary factors in chemical reactions that bond and react with other atoms or molecules. Hence, determining the elements’ reactivity, electronegativity, and the number of bonds they can form. In this article, we will look into what valence electrons are and how to find valence electron for atoms.

What are Valence Electrons?

Valence electrons refer to the electrons located in the outermost energy level of an atom, with the outermost orbitals typically containing these valence electrons that determine if the chemical bonds will form or not. These electrons help to determine an atom’s rate of reactivity, electronegativity, and bonding capacity. The number of valence electrons is easily determined by the group number of the main group elements on the periodic table.

Transition metals have more complex electron configurations. The valence electrons are the outermost shell electrons located in an atom, which help in chemical bond formation. They are in the outermost part of the atom, and they are the least tightly held by the nucleus. Hence, they become available for sharing in bonding and the various chemical reactions.

Calculation of Valence Electrons

To calculate the number of valence electrons in an atom, you can use the following methods:

Periodic Table Method

For s-block elements, the number of valence electrons is equal to the group number on the periodic table. For p block elements, the number of valence electrons is equal to the group number minus ten. For example, the valence electron of aluminium is 13 – 10 = 3. This method makes the valence electrons of the main group elements directly determinable.

Valence electrons of s and p block elements

The valence electrons of the elements belonging to s and p block are mentioned below:

Block	Groups	Number of Valence Electrons
s-block	Group 1 (I)	1
	Group 2 (II)	2
p – block	Group 13 (III)	3
	Group 14 (IV)	4
	Group 15 (V)	5
	Group 16 (VI)	6
	Group 17 (VII)	7
	Group 18 (VIII or 0)	8* (except helium, which has 2)

For example, when you want to know how many valence shell electrons the sodium (Na) has, you can see in the periodic table that it belongs to Group 1. Thus, sodium gets a valence electron that is one. Besides, similarly to find out the valence electrons of the element nitrogen N, you only need to observe that it is at Group 15 on the periodic table or Group V. Nitrogen therefore has five electrons in its valency.

Valence Electron for Transition Elements

In case of transition elements, it is slightly difficult to determine the number of valence electrons using periodic table. However, we can get range of valence electrons from the table below

Groups	Valence Electrons
Group 3	3
Group 4	2 to 4
Group 5	2 to 5
Group 6	2 to 6
Group 7	2 to 7
Group 8	2 or 3
Group 9	2 or 3
Group 10	2 or 3
Group 11	1 or 2
Group 12	2

Electronic Configuration Method

This technique takes into account the electron distribution of the atom and counts the number of electrons at the highest energy level, which can be termed the valence shell. When counted, one can determine the valence electron in any atom by obtaining a clear view of its electron configuration.

For example, if we need to find the electronic configuration of Oxygen then we need to write its electronic configuration. The atomic number of oxygen is 8, hence using Aufbau Principle, Pauli Exclusion Principle and Hund’s rule, we can write electronic configuration of oxygen as follows:

• Electronic Configuration of Oxygen is 1s² 2s² 2p⁴
• Here, the last shell is second shell which has 2 + 4 = 6 electrons
• Hence, the number of valence electrons in Oxygen is 6

Characteristics of Valence Electrons

The characteristics of valence electrons include:

Location: Valence electrons are electrons located in the last energy level, which is the atom’s outermost shell . Hence, such electrons are the ones that are farthest to the nucleus of an atom.

Reactivity: The valence electrons are the active participants of an atom in a chemical bond; hence, it is these valence electrons that define the reactivity of an atom. In other words, these are the electrons used in sharing with another atom to form a chemical bond.

Ionization: Ionization is a process where the valence electrons can be gained or lost. The process influences the charge of the ion, and, therefore, the atom’s character.

Electron Affinity: Electron affinity’s magnitude may be determined by the amount of valence electrons it contains. This is the energy released or absorbed when a neutral atom of an element gains an electron, attracting, and repelling at the same time.

Electron shielding: inner-shell electrons shield the valence electrons; therefore, they are more reactive than their counterpart with respect to another atom or another molecule.

Stability: An atom having a full valence shell is very stable and chemically inactive. An atom with an incomplete valence shell is chemically active.

Importance of Calculation of Valence Electrons

The importance of valence electrons can be summarized as follows:

Chemical reactions: Valence electrons participate in chemical reactions; hence, the reactivities of elements and compounds are best understood by studying the outermost electrons.

Electron configuration: The electron configuration of an atom or ion defines the behavior of valence electrons. In this sense, the behavior of valence electrons is related to the definition of the physical and chemical properties of matter.

Bonding: Chemical bonding in any atom is based on valence electrons; therefore, these bonds play a major role in the making up of a molecule and are considered the basic unit of a compound.

Stability: Valence electrons are key to displaying the stability of elements. This can be seen clearly in a neutral atom or molecule in which the lowest-energy state corresponds to filled or half-filled shells, and the valence electrons reside in these shells.

Conclusion

Understanding valence electrons is fundamental in comprehending chemical bonding, reactivity, and stability of elements. They dictate an atom’s behavior in chemical reactions and determine its bonding capacity. By grasping the concept of valence electrons, we unravel the intricate world of chemistry and the formation of compounds.

FAQs on How to Find Valence Electrons

What is meant by valence electron?

The valence electrons are the electrons in the shell corresponding to the valency of an atom that take an active part in the chemical bonding.

What is the valency of Xenon?

The valency of Xenon is eight because compounds containing it can either give 8 or share 8 electrons.

What is the valency electrons of Te?

There are 6 valence electrons in tellurium (Te) since it is part of Group 16 on the periodic table.

How do you determine valence electrons?

The step one to find valence electron we are to look at the group number for main group elements (1-2 and 13-18). The number of electrons in the s and p orbitals represents the valence electrons