Beta Decay (how many kinds and what kind is this?)

[wormboge]

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What kind of Beta Decay is the following?

Th with a mass of 234 and 90 protons ---> Pa with a mass of 234 and 91 protons + an electron

Also, how many kinds of beta decay are there? (Electron capture, positron emission, and this?)

Is a neutrino emitted in EVERY kind of beta decay?

This is for the MCAT, so if you are 100% sure that we don't need to know the answer to one of these questions please let me know.

 

[sapientnarwhal]

What kind of Beta Decay is the following?

Th with a mass of 234 and 90 protons ---> Pa with a mass of 234 and 91 protons + an electron

Also, how many kinds of beta decay are there? (Electron capture, positron emission, and this?)

Is a neutrino emitted in EVERY kind of beta decay?

This is for the MCAT, so if you are 100% sure that we don't need to know the answer to one of these questions please let me know.

Electron capture and positron emission are essentially the same thing. Beta (-) decay is the emission of an electron, Beta (+) decay is the emission of a positron (simple explanation is a proton loses its + charge which is approx the mass of an electron, thus leaving a neutron). Electron capture is the acquisition of a negative charge by the nucleus, thus “converting a proton to a neutron”. Atomic number decreases by 1 for e- capture and beta (+) emission.

Beta (-) decay results in the “conversion of a neutron to a proton” / “emission of an electron” (again, this is the simplest way to think about this). Atomic number increases by 1.


Correct me if I am wrong, but larger atoms typically undergo beta (+), electron capture, and alpha, while isotopes of smaller atoms typically undergo beta (-) decay?

Also note that only alpha decay results in appreciably reduced mass of the sample.