Question

Discuss briefly the difference between an orbit (as described by Bohr for hydrogen) and an orbital (as described by the more modern, wave mechanical picture of the atom).

Short answer

In conclusion, the main differences between an orbit and an orbital are: Orbits, as described by Bohr, are fixed circular paths in which electrons with quantized energy levels move around the nucleus. Orbitals, as defined by the wave mechanical model, are regions in 3-dimensional space where the probability of finding an electron is high, without a fixed path. The Bohr model is limited to hydrogen atoms, while the wave mechanical model can be applied to all elements. Additionally, the Bohr model is based on classical physics, while the wave mechanical model incorporates quantum mechanics and the wave-particle duality of electrons.

Step-by-step solution

Define the Bohr Model and Orbits

The Bohr model of the atom was proposed by Niels Bohr in 1913. In this model, the electron is assumed to move in well-defined circular paths called orbits around the nucleus. These orbits are discrete, meaning the electron can only occupy specific energy levels. The energy levels are quantized, and an electron can move from one energy level to another by absorbing or emitting a photon of light of the corresponding energy difference. This model was successful in explaining the hydrogen spectrum but has limitations when it comes to more complex atoms.

Define the Wave Mechanical Model and Orbitals

The wave mechanical model, also known as the quantum mechanical model, is a more modern and accurate description of the atom. In this model, rather than considering the electron as a particle moving in a fixed orbit, it is considered as both a particle and a wave. This model uses the Schrödinger equation to calculate the probable location of the electrons in an atom. The concept of an orbital in this model is a region in space where the probability of finding an electron is high. Orbitals are represented by wave functions, or mathematical equations, that indicate the probability density of electrons in a 3-dimensional space around the nucleus. The shape and size of an orbital depend on the quantum numbers associated with the electron.

Highlight the Main Differences

1. Orbits are the paths of electrons in the Bohr model, while orbitals are regions in space with high electron probability in the wave mechanical model. 2. Orbits assume that electrons move in well-defined circular paths around the nucleus with fixed energy levels, while orbitals use wave functions to represent the probability density of electron distribution in 3-dimensional space. 3. The Bohr model is limited to the hydrogen atom, while the wave mechanical model is applicable to all elements in the periodic table. 4. Orbits within the Bohr model imply a fixed position and definite energy for the electron, while orbitals provide only the probable location of the electron with no fixed path. 5. The Bohr model is based on classical physics, while the wave mechanical model is based on quantum mechanics and incorporates the wave-particle duality of electrons. In conclusion, the concept of an orbit in the Bohr model represents a well-defined path for electrons with quantized energy levels, while an orbital in the wave mechanical model represents the probable location of an electron in 3-dimensional space around the nucleus without a fixed path. The wave mechanical model provides a more accurate and comprehensive description of atomic structure than the Bohr model.