- #1

lost_in_phys

- 8

- 0

(A) 2, 1, -1, 1/2

(B) 4, 2, 2, -1/2

(C) 3, 0, 0, -1/2

(D) 3, 2, -2, 1/2

(E) 4, 1, 0, 1/2

Solution:

Electron configuration for arsenic:

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3

2, 1, -1, 1/2 represents a 2 p electron, possible.

4, 2, 2, -1/2 represents a 4 d electron, NOT possible for As.

3, 0, 0, -1/2 represents a 3 s electron, possible.

3, 2, -2, 1/2 represents a 3 d electron, possible.

4, 1, 0, 1/2 represents a 4 p electron, possible.

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I don't understand why its the second one, I do know that all of the numbers are allowed for n, l, ml, ms, but i don't understand how it changes when the element As comes into play.

Thanks for any help