Quantum Mechanics is one of the most important sections of Physics and Chemistry. It describes the properties of atomic and subatomic particles. Orbitals and Sublevels are two parts of electrons carrying atoms that are often confused with each other. Even though the two share a few similarities, they carry different properties.
Orbitals vs Sublevels
The main difference between orbitals and sublevels is that orbitals are spaces inside atoms that have the highest probability of carrying electrons whereas sublevels refer to the division of energy levels carried by the electrons. In an atom, a sublevel is divided into various orbitals.
Orbitals are mathematical functions that describe the most probable location and behavior of electrons in an atom. Each orbital of an atom is characterized into three quantum numbers that describe the electron’s energy, angular momentum, and the vector component of the atom.
Sublevels are defined as energy levels in Quantum Mechanics. In chemistry, these energy levels are associated with electrons of the atom. However, in physics, these energy levels are also associated with the nucleus. The capacity of holding electrons vary with every sublevel.
Comparison Table Between Orbitals and Sublevels
| Parameters of Comparison | Orbitals | Sublevels |
| Definition | Mathematical Functions describing the electrons’ location. | Energy levels of atomic electrons and nucleus. |
| Division | They are types of sublevels. | They are types of orbits. |
| Electron Capacity | One orbital can hold two electrons. | Varies with the capacity of each sublevel. |
| Shape | Symmetrical, dumbbell, or complex shapes. | Not defined as shapes. |
| Purpose | Determining the location of electrons. | Prediction of chemical bonds. |
What are Orbitals?
Orbitals are mathematical functions that describe the most probable location and behavior of electrons in an atom. An orbital is also known as the wave function of the electron. There are four basic types of orbitals including s, p, d, and f-orbital. Each orbital can hold a maximum of two electrons only.
Each orbital of an atom is characterized into three quantum numbers that describe the electron’s energy, angular momentum, and the vector component of the atom. The angular momentum is the electron spin of the electron. This spin of electrons in the orbital is either positive or negative, which are known as spin states of electrons.
As the orbitals radically move away from the nucleus, their sizes gradually increase with every step resulting in higher energy levels. Since the s-orbital is the smallest and closest orbital to the nucleus, it has the highest probability of carrying electrons. On the other hand, the f-orbital is large and far away from the nucleus. It carries a very high level of energy.
Physical characteristics of the orbital including its shape and size depend on the square of the wave function. The orbitals that are close to the nucleus are comparatively more stable. As a result, they have defined shapes. S-orbitals are spherically symmetrical in shape, p-orbitals and d-orbitals are shaped like dumbbells, and f-orbitals have complex diffused shapes as they have high energy levels.
What are Sublevels?
Sublevels are defined as energy levels in Quantum Mechanics. In chemistry, these energy levels are associated with electrons of the atom. However, in physics, these energy levels are also associated with the nucleus. The capacity of holding electrons vary with every sublevel. Sublevels of an atom are divided into various orbitals that carry electrons. There are mainly four principle energy sublevels of atoms. As the sublevel increases, the energy of the electrons present also increases.
Energy sublevel 1 has only one s-orbital, and therefore, it can carry only two electrons. On the other hand, energy sublevel 2 has one s-orbital and three p-orbitals. Since one orbital can carry only 2 electrons, energy sublevel 2 has the capacity of holding 8 electrons. As we move to sublevel 3, the energy levels and capacity significantly increase. Sublevel 3 has five additional d-orbitals than p-orbitals. Sublevel 3 includes a total of nine orbitals which can carry 18 electrons. Similarly, sublevel 4 contains 7 additional f-orbitals than sublevel 3. Hence, it can carry a total of 32 electrons.
The distribution of electrons in all atoms is different. These sublevels determine the distribution of electrons around the nucleus, and hence, it allows us to predict the chemical bonds that the atom can form with other elements.
Main Differences Between Orbitals and Sublevels
- Orbitals have electrons with spin directions whereas sublevels have varying energy levels.
- Orbitals are types of sublevels whereas sublevels are types of orbits.
- Each orbital can hold a maximum of two electrons whereas the capacity of electrons varies with each sublevel.
- Orbitals have no defined boundaries inside the atom whereas sublevels are pre-defined.
- The shape of orbitals can be symmetrical, dumbbell-like, or complex whereas sublevels are not defined as shapes.
Conclusion
The distribution of electrons around the nucleus is undoubtedly one of the most important concepts in Quantum Mechanics. It forms the base for depth in the field and allows us to study how the electrons stay stable while revolving around the nucleus of an atom. While orbitals and sublevels are both key parts of the atomic structure, they are often confused with each other. This is because of the close interrelation that the two have with each other.
The atomic structure of elements is studied on the foundation built by Bohr’s model of an atom, which was proposed by Neil Bohr in 1915. Although there were a few limitations in Bohr’s model, it still did clearly explain the nucleus of an atom, energy levels, and stable revolving of electrons around the nucleus. Four postulates were derived from Bohr’s model to study the atomic structures of all elements.
While sublevels are defined boundaries at constant radii from the nucleus, they directly do not carry electrons in them. Sublevels are further divided into orbitals that carry the electrons within them. As each sublevel has a different number of orbitals, the capacity, energy levels, stability also varies with sublevels.
References
- https://link.springer.com/article/10.1007/BF02461321
- https://iopscience.iop.org/article/10.1088/0022-3700/20/16/028/meta