Question

The number of nodal planes in ${p_x}$ orbital is?
a.) 1
b.) 2
c.) 3
d.) 0

Answer 1

Hint: Before answering this question, we must recall the concepts of nodes and nodal planes of the different subshells. The number of radial and angular nodes can be easily calculated from the principal quantum number and from the azimuthal quantum number of an orbital.

Complete step by step solution:
We also should know that there are three p orbitals namely ${p_x},\,{p_{y\,}}and\,{p_z}$.
Firstly, we must understand that all three orbitals of the p subshell possess equivalent energy and hence, they have similar relation to the nucleus. But they differ in their direction and distribution of charge.
These three orbitals are situated at right angles to each other and are directed along x, y and z axes.
Every p orbital is dumbbell shaped with the two lobes separated by a point of zero probability we call node. Along this node there is a plane of zero electron density. This is the nodal plane also known as angular node.
The azimuthal quantum number determines the number of nodal planes with the general rule:
$No.\,of\,angular\,node = \ell$
Since, for a p orbital, azimuthal quantum number = 1
We can say that the number of nodal planes will also be 1. For ${p_x}$ specifically, the direction is the Y-Z plane.
Hence, the correct answer is Option (A) 1.

Additional information:
The total number of nodes of an orbital is one less than its principal quantum number. The number of radial nodes is the difference between the total number of nodes and the number of nodal planes.

Note: We should note that Radial nodes are present inside the orbital lobes which can be easily understood by looking at the s orbital, which only has radial nodes. But from the p orbital we can understand that angular nodes are not internal contours of 0 electron probability and are rather a plane that goes through the orbital.