Question

The orbital angular momentum quantum number of the step ${{S}_{2}}$ is:
A. 0
B. 2
C. 1
D. 3

Answer 1

Hint: Orbital quantum number is called azimuthal quantum number, which is denoted by l. It basically determines orbital angular momentum and also gives description about the shape of the orbital.

Complete Step by step solution:
- Let’s see some of rules of writing electronic configuration-
Afbau principle: according to this principle the lower energy orbitals are filled before higher energy orbitals.
Hund’s rule: It says that one electron goes into each subshell until all of them are half full before pairing up.
Pauli Exclusion principle: no two electrons can be identified by the same set of quantum numbers
- We know that K, L, M, N are the shells and the numbers. And s, p, d, f are the subshells and l represents the number of subshells. Orbital quantum number is called azimuthal quantum number, which is denoted by l.
- State ${{S}_{2}}$represents 3p subshell. Let’s discuss about M shell:
- For M shell, n=3, number of subshell is $l=0\text{ }to\text{ }(n-1)$
$\begin{align}
& l=0\text{ }to\text{ }(n-1) \\
& l=0\text{ }to\text{ }(3-1) \\
& l=0\text{ }to\text{ }(2) \\
& l=0\text{ }to\text{ }2 \\
& \\
\end{align}$
So, we get l=0 to 2, that is there are three values that are 1,2,3. Therefore M shell has three subshells that are s- subshell, p subshell and d-subshell. And we can say that the value of l=1, is showing 3p subshell.

- Hence, we can conclude that the option (c) is correct, that is the orbital angular momentum quantum number of the step ${{S}_{2}}$is 1.

Additional information:
Let’s see some basic information of Electron Shell (Orbitals)-
- An atom consists of a number of shells around its nucleus. These shells contain the electrons of the atom. The electron shells mostly consist of one or more subshells. The electronic configuration of the atom is decided by the subshells. The number of electrons that can be accommodated in each shell is given by the formula where, n is the number of the electron shell.
- The electron shells are known as K, L, M, N, O, P, Q going from the innermost electron shell to the outermost shell.

Note: - The electronic configuration must be written by the rules of aufbau principle, hund's rule and Pauli exclusion principle. There are some elements that are having exceptions to electronic configuration like chromium, copper.