Have you ever wondered how electrons are arranged inside an atom? Just like planets revolve around the sun, electrons move around the nucleus of an atom in specific paths called electron shells. These shells help us understand why some elements are more reactive, why atoms bond in a certain way and how the periodic table is organized. In this article, we’ll break down what electron shells are, explore their subshells, and learn how electrons arrange themselves. Let’s scroll down to learn all about it.

What Electron Shells are?

Bohr’s Atomic model suggests that electrons move in specific circular paths, or orbits, around the nucleus. These orbits are also known as shells, and each shell has a fixed energy level.

The energy level of a shell is constant and each shell can contain a limited number of electrons. These shells are also referred to as energy levels. They are numbered as 1, 2, 3, 4, etc. or labeled as K, L, M, N, etc. moving away from the nucleus.

The energy of each shell increases as we move away from the nucleus, and each shell must be completely filled with electrons before electrons can start filling the next shell.

Electron shells are like layers around the nucleus where electrons move. Each shell has its own name, holds a specific number of electrons, and sits at a different energy level.

What are Subshells?

The electrons in the same shell do not all have the same energy. Therefore, shells are divided into sublevels, or subshells, based on the energy of the electrons. Each shell contains one or more subshells, which are made up of atomic orbitals.

• Subshells are characterized by Azimuthal quantum numbers (l).
• The value of 'l' depends on the shell (n) it is associated with.
• Subshells are labeled as s (l = 0), p (l =1), d (l = 2), and f (l =3).
• The energy of various subshells within the same shell follows the order: s < p < d <f.
• Subshells with the same 'l' value but different n values have similar shapes, but their size increases with the increase in n value. For example, 2s-subshell is larger than 1s-subshell.
• The maximum number of electrons present in a subshell is given by 2(2l+1).

Electron Count in a Shell

• Each shell is made up of one or more subshells.
• The K shell contains just one subshell - 1s.
• The L shell contains two subshells - 2s, 2p.
• The M shell contains three subshells - 3s, 3p, 3d.
• The N shell contains four subshells - 4s, 4p, 4d, 4f.

The electrons are arranged in the shell and subshell as follows:

Importance of Electron Arrangement

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