Neeraj Anand, Param Anand

Anand Classs Notes explain In Chemistry we can easily find the period, group, and block of an element in the periodic table by looking at its electronic configuration. This means, by knowing how the electrons are arranged in an atom, we can tell where the element is placed in the periodic table. It helps us understand the element’s properties and how it reacts with other elements.

Anand Classes explain how To find the position of an element in the periodic table, we can use its electronic configuration. This helps us easily determine the period, group, and block to which the element belongs. In this post, we’ll go through simple solved examples to understand how to apply these rules step by step. This is very helpful for students preparing for JEE, NEET, and CBSE Class 11 exams.

Anand Classes explain in the periodic table, elements are arranged in periods (horizontal rows) based on the way their electrons fill up different energy levels (shells). Each period starts with the filling of a new energy shell, and the number of elements in a period depends on how many orbitals are available in that shell to hold electrons. Let’s explore the electronic configurations of elements in the first three periods and understand why each period has a specific number of elements.

Anand Classes Notes explain the arrangement of elements in the periodic table follows a specific order based on the filling of electrons in atomic orbitals. From the fourth period onward, the pattern becomes more complex due to the involvement of d- and f-block orbitals. These periods include not only s- and p-block elements but also transition and inner transition elements. Understanding how these orbitals are filled explains why some periods have 18 or even 32 elements, unlike the shorter first three periods.

Anand Classes explains the periodic table is not just a list of elements—it’s a powerful tool that reveals the underlying pattern in chemical behavior. This repeating pattern, known as periodicity, occurs because elements with similar valence shell electron configurations exhibit similar chemical and physical properties. As we move across periods or down groups, these patterns repeat at regular intervals due to the systematic arrangement of electrons, especially in the outermost shell. Understanding this cause of periodicity helps explain why elements in the same group behave alike in reactions and form similar compounds.

Anand Classes Notes explains Atomic radius refers to the distance from an atom’s nucleus to its outermost electron shell, measured in different ways depending on context—covalent radius, metallic radius, or van der Waals radius. Understanding these radius types and their trends is vital for solving Class 11, NEET, and JEE chemistry problems on periodic properties and atomic structure.

Anand Classes Notes explains in atoms with more than one electron, the outer electrons are repelled by the inner electrons due to electron–electron repulsion. This repulsion reduces the full attractive force of the positively charged nucleus on the valence electrons. This phenomenon is known as the screening effect or shielding effect. The greater the number of inner electrons, the larger the shielding effect, which decreases the effective nuclear charge (Zeff) experienced by the outermost electrons. Slater, a scientist, formulated rules to calculate this shielding effect quantitatively, which are essential for understanding atomic structure and periodic trends.

Anand Classes Notes explains across any period in the periodic table, atomic radius generally decreases from left to right. This trend occurs because as the atomic number increases, the nuclear charge grows while electrons are added to the same principal energy level. Without significant shielding from electrons in the same shell, the increased effective nuclear pull draws electrons closer to the nucleus, resulting in a smaller atomic size.

Anand Classes explains the atomic radius of elements shows a clear trend when we move down a group in the periodic table. For both alkali metals (Group 1) and halogens (Group 17), the atomic radius increases as we go from top to bottom. This happens because each successive element down the group has an additional electron shell in its electronic configuration. The added shell increases the distance between the outermost electrons and the nucleus, while the shielding effect of inner electrons reduces the effective nuclear pull. As a result, the atoms become larger despite the increasing nuclear charge.