Question

ap® chemistry: pes
analyzing data from pes

1. which of the following elements might this spectrum represent?

(a) he
(b) n
(c) ne
(d) ar

1. given the spectrum above, identify the element and its electron configuration:

(a) b
(b) al
(c) si
(d) na

Explanation:

Question 1

Step1: Analyze PES peaks (electron counts)

The PES graph has peaks with relative electron numbers: 84.0 (core), 4.7, and 2.0. Sum or analyze shell counts. Neon (Ne) has electron config \(1s^2 2s^2 2p^6\). The core peak (1s) should have 2 electrons? Wait, no—wait, binding energy: higher binding energy is inner shells. Wait, the first peak (84.0) is high binding energy (inner), then two lower (valence). Wait, He has 2 electrons (1s²), N has 7 (\(1s^2 2s^2 2p^3\)), Ne has 10 (\(1s^2 2s^2 2p^6\)), Ar has 18. Wait, the peaks: the high binding energy peak (84.0) is 1s (2 electrons? No, 84.0 is relative, maybe scaled. Wait, the other peaks: 4.7 and 2.0? Wait, no—wait, the y-axis is relative number of electrons. Wait, maybe the first peak (84.0) is 1s (2 electrons), then 2s (2) and 2p (6)? No, 4.7 + 2.0 = 6.7? No. Wait, Ne: 1s² (2), 2s² (2), 2p⁶ (6). So three peaks? Wait, the graph has three peaks? Wait, the first peak (84.0) is 1s (2), then 2s (2, peak ~4.7), then 2p (6, peak ~2.0? No, 2.0 is too low. Wait, maybe the scaling: 84.0 is 2 (1s), 4.7 is 2 (2s), 2.0 is 6 (2p)? No, 2.0 would be 6? No, relative. Wait, He has 2 electrons (1s²), so one peak. N has 7: 1s², 2s², 2p³ (three peaks: 2,2,3). Ne has 10: 1s², 2s², 2p⁶ (three peaks: 2,2,6). Ar has 18: 1s², 2s², 2p⁶, 3s², 3p⁶ (more peaks). The graph has three peaks, matching Ne's shell structure (1s, 2s, 2p). So Ne (C) is correct.

Step2: Eliminate other options

He (A) has 2 electrons (one peak), N (B) has 7 (peaks 2,2,3), Ar (D) has 18 (more peaks). So Ne (C) fits.

Step1: Analyze PES peaks (electron counts)

The PES graph has peaks: 151 (core, 1s²), 12.1 (2s²/2p?), 7.9 (2p?), 1.09 (3s²), 0.58 (3p¹)? Wait, no—binding energy: higher is inner. The peaks: 151 (1s²), 12.1 (2s²), 7.9 (2p⁶)? No, 12.1 + 7.9 = 20? No. Wait, the element options: B (5: \(1s^2 2s^2 2p^1\)), Al (13: \(1s^2 2s^2 2p^6 3s^2 3p^1\)), Si (14: \(1s^2 2s^2 2p^6 3s^2 3p^2\)), Na (11: \(1s^2 2s^2 2p^6 3s^1\)). Let's count electrons from peaks: 151 (1s²), 12.1 (2s²), 7.9 (2p⁶), 1.09 (3s²), 0.58 (3p¹). Sum: 2 + 2 + 6 + 2 + 1 = 13. So Al (13 electrons) has config \(1s^2 2s^2 2p^6 3s^2 3p^1\), matching the peaks (1s, 2s, 2p, 3s, 3p). B has 5 (no 3s/3p), Si has 14 (3p²), Na has 11 (3s¹, no 3p). So Al (B) is correct.

Step2: Confirm electron configuration

Al's electron config is \(1s^2 2s^2 2p^6 3s^2 3p^1\), which matches the five peaks (1s, 2s, 2p, 3s, 3p) with electron counts (2,2,6,2,1) (relative numbers scaled).

Answer:

C. Ne

Question 2