Radioactivity Chp 43

The early years… Mysterious “energy emanations” from some elements 3 different forms: a which Lord Rutherford showed to be helium nuclei b which were shown to be electrons g which were shown to be high energy photons

Decay Series… Alpha Decay Beta Decay emits alpha particle at a precise energy beta decay does not occur at a precise energy but over a continuous range

Conditions for decay…  

Why some nuclei are stable (and others not) Consider either: Minimum mass for a given A,Z Maximum Eb for a given A,Z Far away from the critical point suggests unstable nucleus via b- decay via b+ decay, or EC Example: A = 200, what stable nucleus does the above graph suggest?

Alpha decay occurs when which occurs A > 150

Decay Series…

Uranium-238 Decay Series

Understanding a-Decay