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Alpha Decay - Concept

Teacher/Instructor Kendal Orenstein
Kendal Orenstein

Rutger's University
M.Ed., Columbia Teachers College

Kendal founded an academic coaching company in Washington D.C. and teaches in local area schools. In her spare time she loves to explore new places.

Alpha decay is a type of radioactivity in which the nucleus of an atom loses an alpha particle. Alpha particles are composed of two protons and two neutrons, so they can also be called He2+ nuclei. The result of alpha decay is the transformation of an element into an element found two boxes before it on the periodic table.

Hi so when de- when you're dealing with nuclear reactions uou're dealing with the things inside the nucleus so with protons and neutrons what we're talking about mostlt, and so sometimes when the protons where too many protons are in the nucleus, it becomes a really [IB] really unstable and it's going to want to actually release these these protons so when does that happen?

All nuclei with more more than 83 protons in the nucleus decay spontaneously so they're actually going to automatically without even doing anything start releasing those protons and neutrons to make it smaller and much more stable nucleus so let's look at polonium not only does polo- polonium might now see like the proton neutron to proton ratio it's actually okay for higher atomic numbers 84 is relatively high a 1.5 ratio for neutrons and protons is actually pretty okay. However, we have 84 protons within our nucleus not okay too many so what's going to happen is it's going to release a helium atom a helium nucleus so it's going to release 2 protons and 2 neutrons to try and get that back down to be a little more stable and it's going to in this particular reaction it's going to end up as lead 82 so it transmutate from polonium to lead.

Let's look at the neutron and proton ratio for lead, this is 1.51 it might continue to decay this is actually is a little bit high it's not crazy high but little high so might it continue to decay because it's high might go into beta decay but this might be this might be stable enough to stay where it is so notice also when you're dealing with nuclear reactions that the mass number have to equal if we're going to continue if we're going to use say this arrow is a equals number 210 is equal to 206+204 and 84 is equal to 82+2 so when you're dealing with nuclear reactions make sure that your mass number is equal up and make sure the atomic number is equal up also. But anything with the proton of 83 is going to decay automatically and that's called alpha decay it's going to release an alpha particle.