Names of Atomic Orbitals

Atomic orbitals are regions around the nucleus where electrons are likely to be found most of the time. These orbitals are arranged differently and also have characteristic energies. These atomic orbital names are classified by their main quantum numbers (principal quantum number n) azimuthal quantum numbers (l) and magnetic quantum number (m_l)

The main types of atomic orbitals, labelled by their principal quantum number (n) and azimuthal quantum number (l), are as follows:

• s-orbital
• p-orbital
• d-orbital
• f-orbital

These orbitals are discussed in detail below:

s-orbital

The s (or spherical) orbital is the first atomic orbital in quantum mechanics in terms of its energy. It is known for its rounded form, and its main features are represented by the principal quantum number (n) and the azimuthal quantum number (l). Here are some key points about the s orbital:

1. Shape: S-orbital is spherically-shaped, which means that there is constant probability of finding an electron at any distance from the nucleus in any direction.

2. Principal Quantum Number (n): A principal quantum number is an indicator of the energy level of the electron as well as the size of the orbital. If an s orbital has been filled, the principal quantum number is only a positive integer (n = 1, 2, 3,…).

3. Azimuthal Quantum Number (l): The azimuthal quantum number for the s-orbital is always 0. That means that the shape of that orbital is spherically symmetric.

4. Electron Capacity: The distribution of s orbitals can contain two electrons, and if we apply the Pauli exclusion principle, it holds true that none of the two electrons have the same four quantum numbers.

5. Energy: In multi-electron atoms, the s orbitals occupy the position of the lowest energy states in the same principal level (n) of the orbitals p, d, and f.

6. Designation: The s orbitals carry the notation in the format of their principal quantum number followed by the letter “s”. For example, with the s orbital in the first energy level receiving the symbol 1s, in the second energy level as 2s, and so on.

p-orbital

p-orbital is ranked second atomic orbital in terms of energy level in quantum mechanics. Here are the key points about the p orbital

1. Shape: In contrast to the round shape of an s orbital, the p orbital can be represented by a dumbbell or a figure of eight with two lobes disconnected by a nodal plane in which the probability localization is zero. The lobes are positioned on the three mutually perpendicular axes (x, y, and z) in space.

2. Principal Quantum Number (n): p-orbital starts from second shell and hence has the principal quantum number starting from 2 onwards (n = 2, 3, 4,…). They are written as 2p, 3p, 4p etc.

3. Azimuthal Quantum Number (l): The azimuthal quantum number for the p orbital is 1, which means the sigmoidal shape of the orbitals. Contrary to the fact that the s orbital has no directional properties, the p orbital has some directional qualities owing to its dumbbell shape.

4. Electron Capacity: Since, azimuthal quantum number of p-orbital is 1, its magnetic quantum number is given as -1 to 1 i.e. -1, 0 and 1 corresponding to three sub-orbitals. According to Pauli Exclusion Principle there can be at maximum of two electrons resulting to total six electrons in the orbital.

5. Designation: The designation of orbital specifies the particular axis along which the electrons are located. In the case of the second energy level (n = 2), we have three p orbitals that are named 2px, 2py, and 2pz.

d-orbital

The d-orbital is ranked third in terms of increasing energy level. The details about d-orbital is discussed below:

1. Shape: The d-orbitals are usually complex, with four cloverleaf shapes probing four regions of space, which are similar to doughnut-shaped ones. These lobes all have their own unique characteristics, and they all occur along their own axis in three-dimensional space.

2. Principal Quantum Number (n): The principal quantum number of d orbital starts with 3 onwards. For example, 3d, 4d, 5d etc.

3. Azimuthal Quantum Number (l): The azimuthal quantum number for d orbital is 2.

4. Electron Capacity: There are total of five d-orbitals and each contain two electrons. Hence, there are total ten electrons in d-orbitals

6. Orientation: There are five d orbitals per total (n) that are designated for the first to the fifth principal energy levels, with dxy, dxz, dyz, dx²-y², and dz² as their names. These orbitals can be considered to have certain orientations with respect to the coordinate axes and, therefore, help make the bond in the molecular orbitals more directional.

d-orbitals are important since they determine the electronic configurations of transition metals and their compounds. However, electrons enter d- orbitals along with the s and p orbitals. It is the presence of d electrons that causes transition metals due to which they had variable oxidation state and the form colored compounds and complex ions.

f-orbital

f-orbital is the highest energy orbital among the four orbitals. f-orbitals are found in lanthanides and actinides configurations. The electrons in f subshell gives distinctive properties to these elements, including their magnetic properties, coordination property, and radiation behavior.

1. Shape: In f-orbitals, different lobes and additional splashes formed like an elongated doughnut shape are involved. Therefore, their shapes are more complex. They have bell-shaped structure and oriented in different directions, they form extremely complex and elegant 3D shapes.

2. Principal Quantum Number (n): The principal quantum number for f-orbital starts with four onwards. For example, 4f, 5f, 6f etc.

3. Azimuthal Quantum Number (l): The azimuthal quantum number for f-orbital is 3.

4. Electron Capacity: Each f-orbital can take up to two electrons per orbital and there are seven atomic orbitals. Hence, f-orbital can have maximum of fourteen electrons.

5. Orientation: There are total seven f-orbitals. They are represented by: fxyz, f(x2-y2), fz³, fz(x²-y²), fxyz², fyz³, and fzx³. Those states can have different orientations relative to the centroid and can give up the detailed description of electronic configurations of heavy elements.

Atomic orbitals are regions around the nucleus of an atom where electrons are likely to be found. They are described by quantum mechanics and are characterized by specific quantum numbers. Each type of atomic orbital has a distinct shape, size, and orientation, which corresponds to the probability distribution of finding an electron within that orbital.

In this article, we will learn in detail about atomic orbitals, their names, definition, significance and how they are related to different quantum numbers.