Question

The correct set of quantum numbers for valence electron of $Rb$ (atomic number $37$ ) is:

• A. $5,0,0,-\frac{1}{2}$
• B. $5,1,0,\frac{1}{2}$
• C. $6,0,1,\frac{1}{2}$
• D. $5,1,1,\frac{1}{2}$

Answer 1

Answer: (A)

Electronic configuration of $Rb=[Kr]5s^1$
$Rb$ is alkali metal with valence electron in $5s$ subshell.
Hence, $n=5$
For $s$ electron, $1=0$ and $m=0$.
s can have value $\pm \frac{1}{2}$.
Thus, the correct set of quantum numbers for $Rb$ (atomic number $37$ ) is
$5,0,0,-\frac{1}{2}$.