Question

An electron has a spin quantum number (s) +1/2 and the magnetic number is -1. It can be present in:
A. s-orbital
B. d-orbital
C. p-orbital
D. f-orbital

Answer 1

Hint: For this problem, we have to study the magnetic quantum number and its formula that is 2l +1. By using this formula, we can calculate the value of magnetic quantum number for each orbital i.e. s, p, d and f.

Complete step by step answer:
- In the given question, we have to explain the orbital which has the magnetic number as -1 and spin quantum number as +1/2.
- As we know that there are four types of quantum numbers among which anyone differs in each electron.
- Now, the magnetic quantum number defines the orientation of the orbital in the space and it is denoted by 'm'.
- To calculate the value of 'm' we use the formula i.e. 2l + 1. Here, l is the azimuthal quantum number.
- So, now firstly we have to calculate the value of 'l' by using the formula l = -n to 0 to +n and where n is the principal quantum number which is equal to the shells in which the electron is present.
- So, for s - orbital, the value of 'n' is only 1 and thus the value of l will be:
l = -1, 0, +1.
- Now, we can calculate the value of magnetic quantum number of the s-orbital i.e.
$\text{M = 2l + 1}$by putting the value of l as -1, 0 and 1 we will get three values i.e.
$\text{M = 2 }\times \text{ -1 + 1 = -1}$
$\text{M = 2 }\times \text{ 0 + 1 = 1}$
$\text{M = 2 }\times \text{ 1 + 1 = 3}$
- So, as we can see that the s-orbital can have the value of magnetic quantum number as -1 and also the value of spin quantum number can also be +1/2 and -1/2.
So, the correct answer is “Option A”.

Note: In the question, the azimuthal quantum number is responsible for determining the shape of the orbital whereas the principal quantum number determines the energy and size of the orbitals.