Positrons, Alpha Particles, and Gamma Rays
That's the case with beryllium 7, 7Be4.
Click on it in the applet and see what happens.
It decays to lithium 7--so a proton turns into a neutron. That makes sense...but how do you deal
with the electric charge problem now? Going from Be to Li, you lose charge; emitting an
electron would just make things worse.
Right...so instead you emit a positron--a particle that's just like an electron except
that it has opposite electric charge. In nuclear reactions, positrons are written this way:
So the reaction looks like this:
Good. The applet will show you many other decays that produce either electrons or positrons;
it's easy to tell which, by the "direction" in which the decay moves. Sometimes it even takes
more than one decay to arrive at a stable isotope; try 18Ne or 21O, for
So all radioactive isotopes decay by giving off either electrons or positrons?