Classification of the Elements in the Periodic Table

The elements in the periodic table can be classified in four ways based on their electronic configurations:

• Noble gas elements: Noble gases are elements in the modern periodic table’s group 18. The electronic configuration of this group’s first element (helium) is 1s². The rest of the elements (neon, argon, krypton, xenon, and radon) have an ns² np⁶ outer shell electronic configuration. Since the octet of these elements is complete, they are extremely stable.
• Representative elements: S-block and p-block elements are examples of representative elements. The elements in groups 1 and 2 are referred to as s – block elements (elements with 1s² and 2s² outermost configuration). Groups 13-17 are known as the p-block elements (outermost configuration varies from ns² np¹ to ns² np⁵).
• Transition elements: Transition elements are elements that belong to groups 3 to 12 and have an outer shell electronic configuration of (n-1)d^1-10 ns^1-2. These elements are also referred to as d-block elements.
• Inner transition elements: The inner transition elements are the lanthanides and actinides series, which are found at the bottom of the periodic table. The 4f and 5f orbitals are partially filled in these elements, giving them unique properties.
• Alkali and Alkaline Earth metals: The first two groups on the periodic table’s left side are made up of highly reactive elements (except hydrogen). The Elements of the first group are called Alkali Metals, while the elements of the second group are called Alkaline Earth Metals
• Metalloids and non-metals: Metalloids are typically found in a diagonal line on the periodic table’s right side. These are the elements that separate metals on the left side of the periodic table from non-metals on the right. Because these elements have properties of both metals and nonmetals, they are referred to as metalloids.

Some General Trends of Periodicity in Modern Periodic Table

Atomic Radius: It is the distance from the center of the nucleus to the valence shell of the atom. In Modern Periodic Table, Atomic Radius decreases as we go left to right in a period, and the atomic radius increases as we go down the group.

Ionization Potential: It is the ability of an atom to lose electrons from its valence shell. Higher Ionization Potential means difficult to lose electrons while lower ionization potential means easy to lose electrons. As we go down the group ionization potential decreases and as we move left to right in a group ionization potential increases.

Electronegativity: It refers to the ability of shared pairs of electrons by an element in a molecule. Electronegativity decreases as we go down the group and increases as we move left to right in a period. The most electronegative elements are F > O > N.

Metallic Character: Metals are elements that lose electrons and gain positive charge. The ability to lose electrons is given by ionization potential. Hence as we go down the group metallic character increases and as we move left to right in a period metallic character decreases.

Note: It should be noted that the above trend in properties is general in nature. There exist exceptions in between which we will discuss later.

Read More,

• Characteristics of the Periods and Groups of the Periodic Table
• Position of Elements in the Periodic Table
• Mendeelev Periodic Table

Periodic Classification of Elements refers to the arrangement of elements on the basis of the periodic repetition of their properties. It means the elements which exhibit similar properties on a regular interval are placed in the same group.

In this article, we will learn about, History of the Classification of Elements, various ways to classify elements, their drawbacks, and others in detail in this article.