Textbook 1B 25

[Ruiyu Li 3I]

QUESTION: What is the minimum uncertainty in the speed of an electron confined within a lead atom of diameter 350pm?
ANSWER: 1.65 x 10^5m/s
Hi! I'm a bit confused about this question. Why delta x should be the diameter 350pm instead of the radius 175pm?

[radhika singh 1A]

Hello,

I believe we use the diameter, 350 pm, because of the way we use to model the atom, like an electron within a box. The length of the box is the diameter of the atom. The uncertainty of the position of the electron within that box is at a maximum, 350 pm, which is the diameter of the atom.

hope this helps!

[Maxwell Yao]

Hi,

We use the diameter because the problem states that the electron is confined in the lead atom with a diameter of 350pm. The problem doesn't say anything about using the radius at all, so you should assume that the electron's uncertainty in position is just the 350pm length of the lead atom.

I hope this helps.

[Ruiyu Li 3I]

Thank you!