Question

The probability density plots of $1s$ and $2s$ atomic orbitals are given in figures.
The density of dots in a region represents the probability density of finding electrons in the region.
On the basis of the above diagram, which of the following statements is incorrect?

• A. $1s$ and $2s$ orbitals are spherical in shape.
• B. The probability of finding the electron is maximum near the nucleus.
• C. The probability of finding the electron at a given distance is equal in all directions.
• D. The probability density of electrons for 2s orbital decreases uniformly as distance from the nucleus increases.

Answer 1

The correct option is D The probability density of electrons for 2s orbital decreases uniformly as distance from the nucleus increases.

s-orbitals are spherically symmetric orbitals. Thus, the probability of finding the electron at a given distance is equal in all directions.

Since the number of angular nodes $=l=0(l=s)$, the probability of finding an electron is maximum near the nucleus.

And, total number of nodes $=n-l$

For 1s-orbital, the number of nodes = 0. Thus the probability density is maximum at the nucleus and decreases sharply with the distance from the nucleus.

In case of $2s$-orbital, number of nodes = 2-1 = 1. Thus it has two maxima separated by a region of a nodal surface. The probability density is maximum near the nucleus and decreases sharply to zero and then start increasing again and after reaching a maxima falls abruptly.