Learning Objective: To learn about the different types of orbitals housing electrons in an atom, their visual representation, meaning, and their energy levels.
Skill Level – Intermediate
Prerequisites:
Related –
Pauli's Exclusion Principle
Aufbau’s Principle
Hund's Rule
Quantum numbers (principal, angular, magnetic, spin)
Nodes
Degenerate Orbitals
Difference between Aufbau, Hund, and Pauli
Chapter: Atom
Author's Note: In this section, we will explore the regions with the highest probability of finding electrons, known as orbitals or areas of electron density, which are represented by specific shapes. Regions with no electron density are called nodes. We will examine how electrons are distributed as their numbers increase and how this distribution affects their energy. Electrons closest to the nucleus experience the strongest attractive forces, resulting in higher energy interactions.
Atomic Orbitals - s, p, d, f
An orbital is a location in space around an atom where the probability of finding an electron is the highest.
For example, in a Hydrogen atom with one electron, there is a spherical, not well-defined region around the nucleus where the chances of the electron being present are highest. This region is called the s-orbital, where ‘s’ stands for sharp (due to their sharp spectral lines). A number 1 denotes its closest distance from the nucleus. 2, 3, and so on are used to indicate the increasing distance from the nucleus.
The electron closest to the nucleus experiences the maximum attractive force and therefore, has the lowest energy. Increasing the distance from the nucleus also increases the energy; therefore, 1,2,3,4 is sometimes used to refer to the energy levels.
In the case of hydrogen, the electron is found in the 1s region. The areas where the chances of finding an electron are >95% are marked more strongly with dots or colours when plotting the electron-density diagram.
While marking the density on a graph, the wave’s peak indicates the highest electron density at the nucleus. It drops off exponentially with increasing distance from the nucleus in any direction.
According to a theory proposed by Wolfgang Pauli,....
An experiment in 1997 at the University of Geneva proved that particles at the quantum level ....Therefore, even if the paths...
In an atom like He with two electrons,....
s, p, d, f orbitals
For an atom having more than two electrons, the electrons are found further away from the nucleus in another spherical orbital known as the 2s. The 2s orbital is higher in energy than the 1s orbital and has a wider area. In the 2s orbital, the electrons spend their maximum time away from the nucleus, unlike in 1s, where they are closer. Here, one also encounters areas where the probability of finding the electron is zero, called the nodes. ....
Increasing the number of electrons.....
In the second energy level, in addition to the s-orbital,....
The lobes of the p-orbital are ....
The p orbitals of the second energy level are called ....
In a quick summary, the s-orbital starts from the 1st energy level, .....
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