Based on its position relative to the band of stability, will 80Zn undergo positron decay?

1 Answer
Jun 25, 2014

Based on its position relative to the band of stability, 80Zn will not undergo positron decay.

The band of stability is shown below.

www.quarkology.com

8030Zn has 30 protons and 50 neutrons. The coordinates (30, 50) are above the band of stability.

Elements in this region become more stable by β emission.

8030Zn8031Ga + 01e

The coordinates for 8031Ga are (31, 49). These are closer to the belt of stability, so Zn-80 becomes more stable by β emission.

Ga-80 is itself unstable and decays to Ge-80 by β emission. Ge-80 decays to As-80 by β emission. As-80 decays by β emission to Se-80, which is in the band of stability.

If Zn-80 had undergone positron emission, the equation would have been

8030Zn8029Cu+01e

The coordinates for 8029Cu are (29, 51). These are even further from the band of stability, so positron emission does not occur.

Hope this helps.