PES Provides explanation for shells and orbitals in quantum theory Photoelectric effect — Utilization of photons to remove electrons from atoms Photons have been energized, analyzing the energy needed to remove electrons from an atom/compound Photoelectric spectrum — Energy on x-axis Number of electrons in a subshell on y axis
Photoelectric SpectrumPhotoelectric Spectrum Peaks — Number of subshells/orbitals Peak heights — Number of electrons in subshell Electrons within the same subshell have similar energy values but different orbital energies, energy values vary among subshells Shells with high energies indicate electrons located close to nucleus
Example 1: NaExample 1: Na
Example 2:Example 2: A third period element in the periodic table forms a PES spectrum with three peaks, in the ratio 2:2:1. Name this element. A)Aluminum B)Boron C)Carbon D)Sodium
Example 3:Example 3: Aluminum has the following electron configuration: 1s 2 2s 2 2p 6 3s 2 3p 1 A)How many peaks should be expected in a PES spectrum for Al? B)Which electrons will show the highest energies? Why?
Example 3: (cont.)Example 3: (cont.) Aluminum has the following electron configuration: 1s 2 2s 2 2p 6 3s 2 3p 1 C) Which peak on the spectrum will be the most intense/largest? Why? D) Explain why the peaks for the 3s and 3p electrons would be closely grouped and why they are different than electrons in the 2s and 2p orbitals.