1. Radioactive Decay Series Worksheet Init 5/11/2012 by Daniel R. Barnes based on a years-old worksheet U 238 92  mass number = # of protons + # of neutrons atomic number = # of protons

2. Radioactive Decay Series Worksheet U 238 92  ?? ??? 4 2 He 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.

3. He Radioactive Decay Series Worksheet U 238 92  4 2 ?? ??? 234 90 Th Alpha decay make a nucleus’ mass number go down by four. Alpha decay also makes a nucleus’ atomic number go town by two.

4. 90 234 Th He Radioactive Decay Series Worksheet U 238 92  4 2  ?? ??? 0 e 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

5. 90 234 Th He Radioactive Decay Series Worksheet U 238 92  4 2 ?? ??? 234 91 Pa  0 e 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.

6. Almost. The atomic number is the same, but the mass number has changed. 90 234 Th Radioactive Decay Series Worksheet U 238 92  234 91 Pa   234 92 U 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.

7. 90 234 Th Radioactive Decay Series Worksheet U 238 92  234 91 Pa   234 92 U  230 90 Th 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.