What is Orbital?

The orbital is a mathematical function that shows a wave-like behaviour of electrons or nucleons in Chemistry and Quantum Mechanics. Orbitals are also known as atomic orbitals or electrons. Atomic orbitals are the three-dimensional region of a space surrounding the nucleus in an atom. Covalent bonds are formed by the atoms in atomic orbitals. The commonly found orbitals that fill the space are s,p, d, and f having different shapes of orbitals. In the Pauli Exclusion principle, only two electrons coexist together in orbital space. The electrons having a similar value of n will be in the same shell. Electrons having the same m,n, and l will be in the same orbit and same energy level, but they vary only in spin quantity number. 

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What are the Nodes?

Nodes are defined as the region where the probability of finding the electrons are nil. The nodal plane refers to the plane that goes through the nucleus on which the probability of spotting an electron is zero. The number of nodal planes is equal to the azimuthal quantum number in the orbital. 


Generally, there are two kinds of nodes, radial nodes, and angular nodes. Radial nodes represent the spheres at a fixed radius which occurs because of the principal quantum number increases. Angular nodes are fixed at a certain angle. 


The total number of nodes in an orbital is the sum of radial and angular nodes provided in terms of n and l quantum number. 


N=n-l-1


What are the Types of Orbitals and Their Shapes?

The shape of atomic orbitals can be classified into different types like s,p,d,f, g,h. However, only the first four categories of orbital shapes occur in the ground state of the atom. Following are the types of orbitals and their shapes. 


Given the number of l, the total values permitted gives the orbital a type within a subshell. Four types of atomic orbits go with values of l = 0,1,2,3. 

  • The orbital with the value l=0 represents the s orbitals and these are spherical. 

  • The orbital with the value l=1 represents the p orbitals. It incorporates the nodal plane with a nucleus and these are dumb-bell in shape. 

  • The orbital with the value l=2 represents the d orbitals having a complex structure with two nodal planes. The shape of d orbital is typically the cloverleaf shapes and some are elongated dumb-bells with doughnuts in the centre. 

  • The orbitals with value l=3 represent the f orbitals having a more complex structure. 

The energy of electrons depends on the average distance from the nucleus. The different types of orbitals in atoms with a given set of quantum numbers are associated with specific energy which is known as orbital energy. 


What is the Shape of s Orbital?

The shape of s orbital is spherically symmetrical around the nucleus of an atom like a hollow ball made of fluffy material. The probability of finding the 1s electron is high around the nucleus and decreases as the distance increases from the nucleus. The probability of founding the 2s electron is high around the nucleus and decreases as the distance increases from the nucleus.


The only difference between a 1s and 2s electron is that the 2s electron consists of a node in it. 


Did You Know?

The s orbital of 1s has the highest level of energy. It mainly indicates the energy that is taken out of the electrical bubble of the atom. With the increase in energy, the electrons are located at a distance from the nucleus. 

FAQs (Frequently Asked Questions)

Q1. What is the Shape of the p Orbital?

Ans: The probability of discovering the electrons are maximum on the two lobes of a p orbital on the opposite sides of the lobes. The plane passing through the nucleus has zero possibilities of finding an electron. It gives rise to a dumb-bell shape of p orbital. As l=1, the p orbital has three different orientations known as Px Py and Pz which depends on where the electron density is the maximum such as the x-axis, y-axis, and z-axis. The direction characteristics of p orbital enable it to predict the shape of its molecules. As the principal quantum n increases the p orbitals become larger having high energies (4p > 3p > 2p).

Q2. What is the Shape of the d Orbital?

Ans: The value of l=2, so d orbital will have five different orientations “dxy, dxz,dyz, dx2–y 2, and dz2. The first group contains dxy, dxz, and dyz with each lobes aiming between the two of the axes. The second group contains dx2–y 2, and dz2 with lobes pointing at different axes. It determines the concentration of electron density based on these five axes. The shape of the d orbitals, four out of the fives are similar. These four take the shape of a cloverleaf while the fifth one dz2 assumes the shape of a doughnut with the electron cloud in the centre. However, it has been established that the energy level of the five d orbitals is the same.