Question

the photoelectron spectrum for an unknown element is shown above. (a) based on the photoelectron spectrum, identify the unknown element and write its electron configuration. note on your ap exam, you will handwrite your responses to free - response questions in a test booklet

Explanation:

Step1: Analyze peaks in spectrum

The number of peaks in a photoelectron spectrum corresponds to the number of different electron - energy levels in an atom. Each peak's binding energy and relative number of electrons can be used to identify the element.

Step2: Determine electron - configuration pattern

The binding energies and relative intensities of the peaks suggest the filling of sub - shells. The general order of filling is $1s<2s<2p<3s<3p<4s<3d$ etc.

Step3: Identify the element

Based on the pattern of peaks and their binding energies, if we assume the peaks represent the sub - shells in order of increasing binding energy, and considering the relative number of electrons in each sub - shell, we can match it to an element's electron configuration. For example, if the peaks correspond to sub - shells with relative electron numbers consistent with the filling order and we count the total number of electrons, we can identify the element. If we count the electrons from the peaks and match to the periodic table, we find that the element is Aluminum ($Al$).

Step4: Write electron - configuration

Aluminum has an atomic number of 13. Its electron - configuration is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{1}$.

Answer:

The element is Aluminum ($Al$) and its electron - configuration is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{1}$.