What Is the Difference between Bohr and Schrodinger Model?

The main difference between the Bohr model and the Schrödinger model lies in their treatment of electrons.

Bohr’s model considers electrons as orbiting the nucleus in fixed, discrete orbits, akin to planets orbiting the sun. In contrast, Schrödinger’s model, based on quantum mechanics, describes electrons as existing in probabilistic regions of space called orbitals, where their exact locations and energies are uncertain but can be described by wave functions.

Thus, Schrödinger’s model provides a more nuanced and accurate description of electron behavior compared to Bohr’s simplified planetary model.

Difference between Bohr and Schrodinger Model (With Table)

Aspect	Bohr Model	Schrodinger Model
Nature of Electrons	Electrons are considered as particles orbiting the nucleus in fixed paths.	Electrons are described by wave functions, representing their probability distributions in space.
Orbitals	Electrons occupy discrete, fixed orbits around the nucleus.	Electrons occupy probabilistic orbitals, characterized by their energy levels and shapes.
Quantization	Energy levels and angular momentum are quantized (discrete).	Energy levels are quantized, but electron position and momentum are described probabilistically.
Treatment of Angular Momentum	Angular momentum is quantized and specific to each orbit.	Angular momentum arises naturally from the quantum mechanical treatment of electrons.
Energy Levels	Each orbit corresponds to a specific energy level.	Energy levels are derived from solving the Schrödinger equation and depend on quantum numbers.

What Is Bohr Model?

The Bohr model, proposed by Niels Bohr in 1913, is a simplified model of the atom that depicts electrons as orbiting the nucleus in discrete, fixed orbits or shells.

In this model:

Electrons can only occupy certain orbits around the nucleus where their angular momentum is quantized, meaning it can only take specific values.
Each orbit corresponds to a specific energy level, and electrons can jump between these levels by absorbing or emitting energy in discrete packets (quanta).
The model suggests that electrons do not emit radiation while in these stable orbits unless they change energy levels.

The Bohr model was significant because it provided a framework to explain the stability of atoms and the discrete nature of atomic spectra observed in experiments, such as the emission of light by excited atoms.

However, it has limitations, particularly in describing the behavior of electrons in heavier atoms or in more complex situations, where quantum mechanics (like the Schrödinger equation) is required for a more accurate description.

What Is Schrodinger Model?

The Schrödinger model, also known as the Schrödinger equation or quantum mechanics, is a more advanced and accurate model of the atom compared to the Bohr model.

Proposed by Erwin Schrödinger in 1926, this model:

Describes electrons not as particles with definite paths but as waves described by a wave function, ψ, that evolves over time. This wave function encapsulates the probability amplitude of finding an electron at a particular location around the nucleus.
Electrons are described by their quantum states, which include the principal quantum number (n), orbital angular momentum (l), magnetic quantum number (m), and spin quantum number (s). These quantum numbers define the energy levels and spatial distributions of electrons.
Instead of fixed orbits, electrons exist in orbitals—regions of space around the nucleus where the probability of finding an electron is highest. Orbitals are characterized by their shape (spherical, dumbbell-shaped, etc.) and orientation in space.
The square of the wave function, ψ^2, gives the probability density of finding an electron at a particular point in space.

The Schrödinger model is fundamental to understanding the behavior of electrons in atoms and molecules.

It accurately describes phenomena such as electron distribution, chemical bonding, and the spectral lines of atoms, providing a more comprehensive and mathematically rigorous framework compared to the simpler Bohr model.

Difference between Bohr and Schrodinger Model

Nature of Electrons

Bohr Model: Electrons are considered as particles orbiting the nucleus in fixed paths.
Schrödinger Model: Electrons are described by wave functions, representing their probability distributions in space.

Orbitals

Bohr Model: Electrons occupy discrete, fixed orbits around the nucleus.
Schrödinger Model: Electrons occupy probabilistic orbitals, characterized by their energy levels and shapes.

Quantization

Bohr Model: Energy levels and angular momentum are quantized (discrete).
Schrödinger Model: Energy levels are quantized, but electron position and momentum are described probabilistically.

Treatment of Angular Momentum

Bohr Model: Angular momentum is quantized and specific to each orbit.
Schrödinger Model: Angular momentum arises naturally from the quantum mechanical treatment of electrons.

Energy Levels

Bohr Model: Each orbit corresponds to a specific energy level.
Schrödinger Model: Energy levels are derived from solving the Schrödinger equation and depend on quantum numbers.

Electron Motion

Bohr Model: Electrons move in circular orbits around the nucleus.
Schrödinger Model: Electrons are described as standing waves around the nucleus.

Radiation Emission

Bohr Model: Electrons emit radiation when transitioning between orbits.
Schrödinger Model: Radiation emission is associated with changes in electron energy levels.

Predictive Power

Bohr Model: Predicts discrete spectral lines for hydrogen-like atoms but lacks accuracy for heavier atoms.
Schrödinger Model: Provides accurate predictions of atomic spectra, chemical bonding, and electron behavior in all elements.

Mathematical Formulation

Bohr Model: Based on classical mechanics with ad hoc quantum conditions.
Schrödinger Model: Based on the Schrödinger equation, a fundamental equation of quantum mechanics.

Wave Function vs. Orbits

Bohr Model: Focuses on fixed electron orbits.
Schrödinger Model: Focuses on electron wave functions describing their probable locations.

Concept of Orbitals

Bohr Model: Does not explicitly define orbitals.
Schrödinger Model:Defines orbitals as regions of high probability density where electrons are likely to be found.

Application to Complex Systems

Bohr Model: Limited application to hydrogen-like atoms and simpler systems.
Schrödinger Model: Applicable to all atoms and molecules, providing a unified description of quantum behavior.

Spin and Quantum Numbers

Bohr Model: Does not include spin or other quantum numbers.
Schrödinger Model: Includes spin quantum number and other quantum numbers to describe electron properties.

Relativity

Bohr Model: Does not consider relativistic effects.
Schrödinger Model: Can incorporate relativistic effects, important for heavy atoms.

Foundation of Modern Quantum Mechanics

Bohr Model: Early step in the development of quantum theory.
Schrödinger Model: Fundamental to modern quantum mechanics, forming the basis for understanding atomic and molecular structure.

Similarities between Bohr and Schrodinger Model

Both models incorporate the concept of quantized energy levels for electrons in atoms.
Both models address the stability of atoms by proposing that electrons occupy specific energy levels or orbits where they do not emit radiation unless transitioning between these levels.
Both models provide accurate descriptions for hydrogen-like atoms (e.g., hydrogen, singly ionized helium), where the electron interacts with a single proton.
Despite its limitations, the Bohr model successfully predicts the discrete spectral lines observed in the emission and absorption spectra of hydrogen-like atoms, which is also a success of the Schrödinger model.
Both models played crucial roles in the development of quantum mechanics.

Conclusion

In conclusion, the differences between the Bohr and Schrödinger models of atomic structure highlight the evolution from a semi-classical to a fully quantum mechanical understanding.

The Bohr model, with its concept of discrete orbits and quantized energy levels, laid foundational groundwork for explaining atomic spectra and stability. However, it was limited by its inability to accurately describe more complex atoms and molecules.

Conversely, the Schrödinger model revolutionized atomic theory by introducing wave mechanics and describing electrons as probabilistic entities defined by wave functions. This model not only refined our understanding of electron behavior in all elements but also provided a robust framework for predicting atomic spectra, chemical bonding, and the structure of molecules.

While the Bohr model remains historically significant for its initial insights into quantum phenomena, the Schrödinger model stands as the cornerstone of modern quantum mechanics, offering a more comprehensive and mathematically rigorous approach to understanding the fundamental nature of atoms and their constituents.