Question

what element does this pes represent?
photoelectron spectrum
a. sc
b. ca
c. ne
d. mg
enter the answer choice letter.

Explanation:

1. Analyze the PES peaks: The peak heights (relative number of electrons) correspond to electron counts in subshells. From left to right (lowest to highest binding energy), the peaks represent 2, 6, 2, 6, 2 electrons.
2. Sum the electrons: $2 + 6 + 2 + 6 + 2 = 20$. This equals the atomic number of the element.
3. Match to options: Calcium (Ca) has an atomic number of 20, with the electron configuration $1s^22s^22p^63s^23p^64s^2$, which matches the electron counts from the PES peaks.

Answer:

B. Ca