Which of the following sets of quantum numbers represents the 19th electron in chromium? (Z= 24 for Cr)

Question

Which of the following sets of quantum numbers represents the 19th electron in chromium? (Z= 24 for Cr) (A) (4,1,-1,+(1/2)) (B) (4,0,0,+(1/2)) (C) (3,2,0,-(1/2)) (D) (3,2,-2,+(1/2))

Tardigrade Admin · Accepted Answer

The ground state electronic configuration of

C r

is as

_{24} C r = [A r] 3 d^{5}, 4 s^{1}

∵

The

1 9^{th}

electron enters in

4 s^{1}

subshell.
For

4 s^{1}

n = 4, l = 0

[For

s

orbital,

l = 0

]

m = 0 [∴ m = - l to + l]

s = + 1/2

Q. Which of the following sets of quantum numbers represents the $1 9^{t h}$ electron in chromium? ( $Z = 24$ for $C r$ )

$(4, 1, - 1, + \frac{1}{2})$

$(4, 0, 0, + \frac{1}{2})$

$(3, 2, 0, - \frac{1}{2})$

$(3, 2, - 2, + \frac{1}{2})$

The ground state electronic configuration of $C r$ is as
$_{24} C r = [A r] 3 d^{5}, 4 s^{1}$
$∵$ The $1 9^{th}$ electron enters in $4 s^{1}$ subshell.
For $4 s^{1}$
$n = 4, l = 0$ [For $s$ orbital, $l = 0$ ]
$m = 0 [∴ m = - l to + l]$
$s = + 1/2$

Q. Which of the following sets of quantum numbers represents the 19th electron in chromium? (Z=24 for Cr)

(4,1,−1,+21​)

(4,0,0,+21​)

(3,2,0,−21​)

(3,2,−2,+21​)