Radioactive Decay Series WorksheetInit 5/11/2012 by Daniel R. Barnes based on a years-old worksheet

U23892

mass number = # of protons + # of neutrons

atomic number = # of protons

Radioactive Decay Series Worksheet

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???42He

alpha particle

An alpha particle has a mass number of 4 and an atomic number of two.

Because of its atomic number, an alpha particle is, essentially, a helium nucleus.

He

Radioactive Decay Series Worksheet

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42

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90Th

Alpha decay make a nucleus’ mass number go down by four.

Alpha decay also makes a nucleus’ atomic number go town by two.

90234Th

He

Radioactive Decay Series Worksheet

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42

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???0-1e

An beta particle has a mass number of 0 and an atomic number of negative one.

A beta particle is, essentially, an electron that gets shot out of a radioactive nucleus at very high speed.

beta particle

90234Th

He

Radioactive Decay Series Worksheet

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42

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91Pa

0-1e

During beta decay, a neutron in the nucleus of the atom splits into a proton and an electron.

The proton remains in the nucleus, causing its atomic number to increase by one, while the electron is ejected as a beta particle.

Almost. The atomic number is the same, but the mass number has changed.

90234Th

Radioactive Decay Series Worksheet

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234

91Pa

23492U

It looks like the uranium atom has turned back into uranium again, but is it exactly the way it was at the beginning?

The atom is now the same element it used to be, but it is a different isotope of uranium.

90234Th

Radioactive Decay Series Worksheet

U23892

234

91Pa

23492U

230

90Th

Alpha decay causes mass number to go down by four and atomic number to go down by two.

Beta decay causes mass number to stay the same and atomic number to go up by one.

SUMMARY:

A gamma particle might come out during alpha or beta decay, but when it does, it does not affect the mass number or the atomic number.