Question

An orbital with l = 0 is:
(A) Symmetrical about X axis only
(B) Symmetrical about Y axis only
(C) Spherically symmetrical
(D) Unsymmetrical

Answer 1

Hint: ‘l’ represents the subshell or the Azimuthal quantum number which is associated with the angular momentum of the electron. It also determines the shape of the subshell in which the electron is present.

Complete answer:
The position of any electron in an atom is described with the help of quantum numbers. There are 4 types of quantum numbers used:
1) Energy or principal quantum number (n): It identifies the shell in which the electron lies. With increase in the value of n the size and the number of allowed orbitals also increases.
For n = 1 the shell is ‘K’, n = 2 it is ‘L’, n = 3 it is ‘M’, n = 4 it is ‘N’ and so on.
2) Azimuthal quantum number or orbital angular momentum (l): It is associated with the angular momentum of an atomic electron and is also known as the second quantum number. It determines the shape of the electron's orbital or the subshell.
For a given shell number (n), l can have n values ranging from 0 to (n-1). The possible values of l are 0, 1, 2, 3…. (n-1).
Example: n = 1 has l = 0, n = 2 has l = 0,1 , etc.
Every value of l corresponds to a different subshell. The value of l = 0 represents ‘s’ subshell, l = 1 represents ‘p’ subshell, l = 2 represents ‘d’ subshell, l = 3 represents ‘f’ subshell and so on.
Each of these orbitals has a different shape. ‘s’ subshell is spherical in shape, ‘p’ is dumbbell shaped, ‘d’ is double dumbbell, etc.
3) Magnetic quantum number (${m_l}$): It describes the energy levels available within a subshell and tells us about the projection of the orbital angular momentum along a specific axis.
The value of ${m_l}$ ranges from l to (-l).
Example: l = 1 is p subshell and for it ${m_l}$= -1, 0 , 1. This means that the p subshell has 3 orbitals.
4) Spin quantum number (${m_s}$): It describes the spin or intrinsic angular momentum of an electron within the orbital and gives the projection of its spin angular momentum along the axis.
The value of ${m_s}$= ± 1/2
Now the question is asking about l = 0. It represents the ‘s’ subshell. Since the shape of ‘s’ subshell is spherical, it will be spherically symmetrical.

So, the correct option is: (C) Spherically symmetrical.

Note: Azimuthal quantum number represents the subshell and is associated with the angular momentum of the electron and also the shape of the subshell. For every value of n, l = 0 to (n-1). Values of l = 0, 1, 2, 3, 4…. (n-1).