AP Chemistryeasymcq1 pt
In a PES spectrum, the 1s peak appears at a much higher binding energy than the 2s peak. Why?
A.1s electrons are closer to the nucleus
B.1s holds more electrons
C.1s electrons are moving slower
D.1s electrons are spin-paired
Explanation
Core Concept
Core 1s electrons feel nearly the full nuclear charge with no shielding, so ejecting them requires the most energy. PES measures exactly that removal energy, placing 1s at the high-binding-energy end.
Correct Answer
A1s electrons are closer to the nucleus
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