1. NUCLEAR CHEMISTRY Chapter 20

2. Nuclear Chemistry Radioactivity is the emission of subatomic particles or high- energy electromagnetic radiation by the nuclei of certain atoms. These atoms are considered radioactive. Types of radioactivity: Alpha Decay: an unstable nucleus emits a particle composed of two protons and two neutrons – which is essentially what element? Beta Decay: an unstable nucleus emits an electron. A neutron changes into a proton and an electron and the electron is emitted. It is known as a “beta β particle” Gamma Ray Emission: the emission of electromagnetic energy.

3. Nuclear Chemistry

4. Nuclear Chemistry

5. What is a half life, t 1/2 ? (page 688) PRACTICE: Phosphorus-32 has a half-life of 14.3 days. How many milligrams of phosphorus-32 remain after 57.2 days if you start with 4.0 mg of the isotope? How many half-lives have occurred after 57.2 days?__________ (# of t 1/2 ’s that have occurred)(original mass of substance) = ______ KEEP THIS CALCULATION ATTEMPT IN YOUR NOTES. I WILL CHECK IT ON THE NEXT NOTEBOOK CHECK! For help, refer to page 689, sample problem B.