The quantum numbers of the last electron of arsenic could be: A)n = 4,ℓ = 2,m_ℓ = 1,m_s = +1/2 B)n = 4,ℓ = 1,m_ℓ = 1,m_s = +1/2 C)n = 3,ℓ = 1,m_ℓ = 1,m_s = +1/2 D)n = 4,ℓ = 3,m_ℓ = 1,m_s = +1/2 E)n = 4,ℓ = 1,m_ℓ = 1/2,m_s = 0

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Quizplus · Accepted Answer

The electron configuration of arsenic is [Ar]3d104s24p3, indicating that the last electron is in the 4th energy level (n=4) and in the p-subshell (ℓ=1). The value of mS does not depend on the quantum numbers n and ℓ, so it can be any value of +1/2 or -1/2. Therefore, option B is the best choice, since it correctly specifies n=4, ℓ=1, and mS=+1/2. Options A, C, and D are incorrect because they have either the wrong value of n or ℓ, or an incorrect value of mS. Option E is incorrect because it states that ℓS = 1/2, which is not a valid value for the angular momentum quantum number.

The Quantum Numbers of the Last Electron of Arsenic Could