HardChemistryHigh School (11–12)Structure of the Atom › Subatomic Particles and Atomic ModelsNumericalJEE Main NEET BITSAT WBJEE Board Exam

Alpha particles of 6.0 MeV are fired straight at a silver nucleus, with Z = 47 and A = 108…

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Alpha particles of $6.0\ \text{MeV}$ are fired straight at a silver nucleus, with $Z = 47$ and $A = 108$ . Find the distance of closest approach, and compare it with the radius of the nucleus. What energy would an alpha particle need to just reach the nucleus's surface?

Need a reminder? The key ideaShow

A small, dense, positive nucleus turns back the few alpha particles that come close. Closest approach: $d = \dfrac{2Z}{KE} \times 1.44\ \text{MeV fm}$ . Nuclear radius: $R = 1.2\ \text{fm} \times A^{1/3}$ . An atom is about $10^{5}$ times wider than its nucleus.

The worked solution

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