Easy way to memorize Radioactive Decay methods??

[axp107]

No matter how many times I study radioactive decay, the answer just eludes me on problems...

Its partially because every time I see a problem, they use different terminology. Sometimes they just say "beta" particle. How're you supposed to know if its positron or not?

Anyone have any good mnemonics?

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[MedChic]

What helps me remember these is that the charge in the universe must always remain constant...so when a positive charge is created, then a negative charge must also be created. Therefore, if you have a proton emitted, you must add a -1 to the atomic number of the element to equalize the charge.

 

[vicinihil]

What helps me remember these is that the charge in the universe must always remain constant...so when a positive charge is created, then a negative charge must also be created. Therefore, if you have a proton emitted, you must add a -1 to the atomic number of the element to equalize the charge.

so this is how I remember it.

Beta emission, unless otherwise specified, will always refer to an ELECTRON. Therefore the electron released, during beta emission, must come from the nucleus. Well, how do you get an electron from the nucleus, YOU MAKE IT...by breaking down a nucleus into a proton and an electron (charges and mass add up to that of a neutron). So now, the electron goes out and proton is added to the overall mass of the "nucleons" so mass doesn't change but atomic number increases.

For positron emission, the opposite occurs. A proton--> positron + neutron

Positron goes out, neutron is added to other nucleons, therefore the mass, again, doesn't change, but the atomic number DECREASES because you broke down a proton.

Make sense?

 

[Hindiana_Jones]

The easiest way for me to do this was memorize the "chemical equation (?) for each, showing how they decay.

Alpha Decay: The nucleus loses a Helium atom. So Atomic mass decreased by 4, and atomic number decreases by 2.

Beta Decay: Beta decay involves an electron. In Beta positive decay you form a proton and lose a neutron. This is because a neutron breaks down into a proton, electron and anti neutrino. Your mass number stays the same, and the atomic number increases by 1 (one more proton). You also release an electron and an anti neutrino.

In Beta negative decay, you lose a proton, so the mass number remains constant and the atomic number decreases by 1. A proton becomes a neutron, a positron, and a neutrino.

EK also discusses electron capture and positron emission. These are both forms of Beta decay. In electron capture a orbital electron and a proton form a neutron. You do not form an ion, because the atom has lost both an electron and a proton.

In positron emission a proton forms when a neutron is broken down into a proton, positron and neutrino.

Gamma decay does not involve the loss of any nucleons. In Gamma decay, an excited proton releases a high energy photon. This is the Gamma particle that is released. Alpha or Beta decay can result in Gamma decay.