Yahoo Answers is shutting down on May 4th, 2021 (Eastern Time) and beginning April 20th, 2021 (Eastern Time) the Yahoo Answers website will be in read-only mode. There will be no changes to other Yahoo properties or services, or your Yahoo account. You can find more information about the Yahoo Answers shutdown and how to download your data on this help page.
Trending News
I REALLY NEED help in earth science!!!?
I really need answers to these questions.
A. When an alpha particle is emitted, how do the mass number and the atomic number change, if at all?
2. When three-quater of a radioactive isotope has decayed to become the stable daughter product,---------- half lives have occured.
1 Answer
- Howard HLv 71 decade agoFavorite Answer
1. An alpha particle consists of two protons and two neutrons (equivalent to a helium nucleus). A proton has a mass number of +1. A neutron has a mass number of +1. Therefore a nucleus that emits an alpha particle loses 4 mass numbers. A proton has an atomic number of +1. A neutron has an atomic number of 0. Therefore, the nucleus that emits an alpha particle will lose 2 atomic numbers.
After one half-life, half the isotope has decayed. After another half-life, half of the rest has decayed, so in total 3/4 has decayed. After a third half-life, 7/8 has decayed. Etc.
