The concept of electron clouds is a part of the quantum mechanical model of the atom, which describes the behaviour of electrons in terms of probability distributions rather than fixed orbits. In this model, electrons are not confined to specific orbits as proposed by the Bohr model but instead are described by electron clouds or probability distributions.
Electrons in an atom are organized into energy levels or shells. These shells are designated by principal quantum numbers (n = 1, 2, 3, …), with higher values of n corresponding to higher energy levels. Electrons in higher energy levels are farther from the nucleus.
Each energy level is divided into subshells or orbitals. These are designated by letters (s, p, d, f). The number of subshells in an energy level is equal to its principal quantum number (n). For example, the first energy level (n = 1) has one subshell (s), the second energy level (n = 2) has two subshells (s and p), and so on.
An orbital is a region in space where there is a high probability of finding an electron. Each orbital can hold a maximum of two electrons with opposite spins. The shape of the orbital depends on its type (s, p, d, f).
The electron cloud is a visual representation of the probability distribution of finding an electron in a particular region around the nucleus. It is not a physical boundary but rather a region where the electron is likely to be found.
The s orbital is spherical and is found in all energy levels. The p orbitals are dumbbell-shaped and are present in the second energy level and higher. The d and f orbitals have more complex shapes and are found in higher energy levels.