Question

the complete photoelectron spectrum of an element is given above. which of the following electron configurations is consistent with the spectrum?
a 1s²2s²2p¹
b 1s²2s²2p⁶3s²3p³
c 1s²2s²2p⁶3s²3p⁶
d 1s²2s²2p⁶3s²3p⁶4s²3d⁵

Explanation:

Step1: Analyze peaks in spectrum

The photoelectron spectrum shows 5 distinct peaks, which correspond to different sub - shells of electrons. Each peak represents electrons in a particular sub - shell with a characteristic binding energy.

Step2: Check number of sub - shells in options

• Option A: $1s^{2}2s^{2}2p^{1}$ has 3 sub - shells ($1s$, $2s$, $2p$).
• Option B: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{3}$ has 5 sub - shells ($1s$, $2s$, $2p$, $3s$, $3p$).
• Option C: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}$ has 5 sub - shells, but the relative intensities of electrons in sub - shells do not match the spectrum.
• Option D: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{5}$ has 6 sub - shells ($1s$, $2s$, $2p$, $3s$, $3p$, $4s$, $3d$).

Answer:

B. $1s^{2}2s^{2}2p^{6}3s^{2}3p^{3}$