MediumChemistryHigh School (11–12)Structure of the Atom › Quantum Mechanical Model of the AtomConceptualBoard Exam
Give two reasons, one from de Broglie and one from Heisenberg, why we cannot say that an electron…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Give two reasons, one from de Broglie and one from Heisenberg, why we cannot say that an electron moves in a circular orbit with a known speed.
Need a reminder? The key ideaShow
De Broglie: . Heisenberg: . Both matter only for very small particles such as electrons, and together they rule out a fixed path.
The worked solution
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Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. De Broglie. The electron is a wave, spread out around the nucleus, not a point travelling along a line.
Step 2. Heisenberg. To follow an orbit we would need its position and speed exactly at every moment. The uncertainty principle forbids knowing both.
Answer: the electron is a spread-out wave, and its position and speed cannot both be known.
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