Question

Which set of quantum numbers ($n,l,m,s$) represents the outermost electron in a gaseous aluminium atom?

• A. $2,1,0.+\frac{1}{2}$
• B. $2,1,-1.+\frac{1}{2}$
• C. $3,0,0.+\frac{1}{2}$
• D. $3,1,-1.+\frac{1}{2}$

Answer 1

The correct option is D $3,1,-1.+\frac{1}{2}$

Electronic configuration of aluminum is $1s^{2}2s^{2}2p^{6}3s^{2}3p^1$ hence, the outermost electron enters in M shell i.e $n=3$. The outermost electron enters into the p subshell i.e $l=1$. As the electron enters in $p_x$ orbital hence, $m=-1$. For first electron $s=+\frac{1}{2}$.

Set of quantum numbers ($n,l,m,s$) for outermost aluminium gaseous atom is $(3,1,-1,+\frac{1}{2})$.