Atomic Orbital: Definition, Types, Shapes, and Diagram (2024)

What Is An Atomic Orbital?

From the electron cloud model concept, we already know that electrons do not revolve around the atomic nucleus in fixed orbits. Instead, they form a cloud of negative charge around the nucleus. This concept was given by Schrödinger through an equation called the Schrödinger equation.

By solving the equation, we obtain a mathematical expression, called wave function, which describe the probability of finding electrons at certain regions within an atom. This wave function can be described as atomic orbital.

In simple words, atomic orbital refers to a region of space with a high probability of finding the electron. It is depicted as a three-dimensional region with a 95% probability of tracing an electron. On the contrary, the regions around the atomic nuclei where the likelihood of finding electrons is zero are referred to as nodes or nodal planes.

Types of Orbitals

Atomic orbitals are of four different types: s, p, d, and f. They are commonly denoted by a combination of letters and numerals, such as 1s, 2p, 3d, 4f, etc. Here, the numerals indicate principal quantum numbers (n), designating the energy levels as well as relative distance from the nucleus. On the other hand, the letters s, p, d, and f denote the orbital shape.

Each orbital can only accommodate two electrons due to their spin. As the energy levels increase, the electrons are located further from the nucleus, making the orbitals bigger. The number of orbitals that each subshell can accommodate depends on the values of magnetic quantum number (ml). The value of ml ranges from -ℓ to +ℓ, including zero, where ‘ℓ’ stands for azimuthal quantum number.

s orbital

It is a spherical space encircling the nucleus. As it is spherically symmetrical, there is an equal probability of finding electrons in all directions. The size of the orbital increases with the increase in principal quantum number (n). The order of size is 1s < 2s < 3s < 4s and so on. We get a single ‘ml’ value for s-orbital, i.e., zero. So, every subshell has only one s-orbital.

p orbital

As we move from the first energy level, there is another orbital called p orbital. It looks like two lobes or ballons tied at the nucleus, giving a dumbbell shape. Electrons can be found in either of the two lobes. The ‘ml’ value for p orbital ranges from -1 to +1, i.e., -1, 0, +1 (here, ℓ = 1). Thus, every subshell can accommodate three p-orbital.

Depending on how the lobes lie along the x, y, or z-axis, they are designated as 2px, 2py, and 2pz. The axes of these three p orbitals are mutually perpendicular. Similar to s orbitals, the size of p orbitals increases with an increase in the principal quantum number, such as 2p < 3p < 4p and so on.

d orbital

At the third level, there is another orbital called d orbital, in addition to s and p orbitals. There are five d-orbitals in each subshell, as its ‘ml’ values are -2,-1, 0, +1, +2. These orbitals are designated as dxy, dyz, dxz, dx2–y 2 , and dz2.

Out of these five d orbitals, the first four are clover-shaped. However, the energy of all five d orbitals is the same. Similar to other orbitals, the size of this orbital also increases with an increase in the principal quantum number, such as 3d < 4d < 5d and so on.

f orbital

Upon reaching the fourth energy level, there is f orbital. They are oriented in the shape of double dumbbells. The ‘ml’ value for this orbital ranges from -3 to +3, i.e., -3, -2, -1, 0, +1, +2, +3 (here, ℓ = 3). Thus, every subshell can accommodate seven f-orbital. The size of f orbital can be arranged as 4f < 5f < 6f and so on.

Filling Order of Atomic Orbitals

Electrons enter into each orbital following the Aufbau principle. According to this principle, the subshells get filled in order of increasing value of ‘n + ℓ’. In the case of an equal value of ‘n + ℓ’, electrons are assigned to the subshell having a lower ‘n’ value.

The table below shows the ‘n + ℓ’ value of some orbitals, arranged in increasing order of ‘n’ values:

OrbitalPrinciple quantum number (n)Azimuthal quantum number (l)Sum (n + ℓ’)

Article was last reviewed on Thursday, February 2, 2023

Atomic Orbital: Definition, Types, Shapes, and Diagram (2024)


What are 4 types of atomic orbitals and their shapes? ›

An s-orbital has a spherical nucleus in the center, a p-orbital is dumbbell-shaped, and four of the five d orbitals are cloverleaf shaped. The fifth d orbital is fashioned like a long dumbbell with a doughnut in the center. The orbitals of an atom are organized into layers or electron shells.

What is an orbital and what are the types of orbitals? ›

2) Orbitals are combined when bonds form between atoms in a molecule. There are four types of orbitals that you should be familiar with s, p, d and f (sharp, principle, diffuse and fundamental). Within each shell of an atom there are some combinations of orbitals.

What describes the shape of the atomic orbitals? ›

The angular quantum number (l) describes the shape of the orbital. Orbitals have shapes that are best described as spherical (l = 0), polar (l = 1), or cloverleaf (l = 2). They can even take on more complex shapes as the value of the angular quantum number becomes larger.

What is the meaning of atomic orbital? ›

An atomic orbital is a mathematical term in atomic theory and quantum mechanics that describes the position and wavelike behaviour of an electron in an atom. A maximum of two electrons, each with its own spin quantum number s, will occupy each of those orbitals.

What are the 4 types of orbitals how many electrons do they each hold? ›

However, the electron can exist in spin up (ms = +1/2) or with spin down (ms = -1/2) configurations. This means that the s orbital can contain up to two electrons, the p orbital can contain up to six electrons, the d orbital can contain up to 10 electrons, and the f orbital can contain up to 14 electrons.

What are the orbital types in order? ›

The order of the electron orbital energy levels, starting from least to greatest, is as follows: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p.

What are the 4 types of orbitals? ›

The four different orbital forms (s, p, d, and f) have different sizes and one orbital will accommodate up to two electrons at most. The orbitals p, d, and f have separate sub-levels and will thus accommodate more electrons.

What is an orbital diagram in chemistry? ›

What are Orbital Diagrams? Electron orbital diagrams are diagrams used to show the energy of electrons within the sublevels of an atom or atoms when used in bonding. Single atom diagrams (atomic orbital diagrams) consist of horizontal lines or boxes for each sublevel.

What shape is f orbital? ›

F orbitals are the orbitals that, in total, have the affinity to accommodate 14 electrons in them. The shape of the f orbital is tetrahedral.

How to remember orbital shapes? ›

There are four known shapes of atomic orbitals. First, what are the orbitals? They are s, p, d, and f - in that order You can remember them with the word "speedIfy", which may or may not be an actual word.

Why are there different shaped orbitals? ›

In increasing energy order we find that patterns arise in the eigenvalues for energy, angular momentum etc. The angular momentum is what gives the orbitals their shapes.

What is the shape of an atom? ›

Atoms lack a well-defined outer boundary, so their dimensions are usually described in terms of an atomic radius. This is a measure of the distance out to which the electron cloud extends from the nucleus. This assumes the atom to exhibit a spherical shape, which is only obeyed for atoms in vacuum or free space.

How to explain atomic structure? ›

Atoms consist of three basic particles: protons, electrons, and neutrons. The nucleus (center) of the atom contains the protons (positively charged) and the neutrons (no charge). The outermost regions of the atom are called electron shells and contain the electrons (negatively charged).

How to identify orbitals? ›

Each orbital is denoted by a number and a letter. The number denotes the energy level of the electron in the orbital. Thus 1 refers to the energy level closest to the nucleus; 2 refers to the next energy level further out, and so on. The letter refers to the shape of the orbital.

What is the shape of all the d orbitals? ›

The general shape of the d-orbitals can be described as "daisy-like" or "four leaf clover" with the exception of the dz2 orbital which looks like the donut with a lobe above and below. All the d-orbitals contain 2 angular nodes.

What is the shape of the orbit? ›

All orbits are elliptical, which means they are an ellipse, similar to an oval.

What is the shape of an S orbital? ›

The shape of the s orbital is a sphere; s orbitals are spherically symmetric. The nodes of s orbital is n-1; the angular nodes is l, which is 0 for all s orbitals; the radial nodes is n-l-1, which is n-1 for all s orbitals. Therefore, s orbital only has radial nodes, which are spheres.

What is the shape of the 1s orbital? ›

This orbital is equivalent to the innermost electron shell of the Bohr model of the atom. It is called the 1s orbital because it is spherical around the nucleus. The 1s orbital is always filled before any other orbital. Hydrogen has one electron; therefore, it has only one spot within the 1s orbital occupied.


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