Question

Which of the following set of quantum number is correct for an electron in 5f orbital?

• A. $n=5,l=3,m=+4,s=+\frac{1}{2}$
• B. $n=5,l=4,m=-4,s=-\frac{1}{2}$
• C. $n=5,l=2,m=-1,s=+\frac{1}{2}$
• D. $n=5,l=3,m=+1,s=+\frac{1}{2}$

Answer 1

Answer: (D)

Any sub-orbit is represented as nl such that n is the principle quantum number (in the form of values) and l is the azimuthal quantum number (its name).

Value of $l<n$	$l$	$0$	$1$	$2$	$3$	$4$
		s	p	d	f	g

Value of m: -l to +l including 0,

Value of s: $+\frac{1}{2}$ or $-\frac{1}{2}$

for 5f: n = 5, l = 3, m = any value between -3 to +3.

Hence n = 5, l = 3, m = +1, s = $+\frac{1}{2}$ is the correct set. In other options these conditions are not satisfied so they are incorrect.