Unstable Nuclei and Radioactive Decay Objectives: 9.0 Distinguish between chemical and nuclear reactions. 9.3 Identifying types of radiation and their properties AOD C.9.4 Identify nuclear reactions as those types involving nuclear particles, including alpha particles, beta particles, and gamma rays.

Radioactivity In chemical reactions, atoms recombine, but maintain their identity. If an atom loses or gains a proton, it becomes a different element. This is what happens in nuclear reactions, because they involve a change in the nucleus.

Radioactivity (cont.) Some unstable, radioactive atoms change this way when they emit radiation (both rays and particles), until they reach a stable, nonradioactive form. What is this process called? Answer: Radioactive decay

Types of Radiation Three-Tab Foldable: –Alpha radiation –Beta radiation –Gamma radiation

Alpha Radiation Alpha particles contain 2 protons and 2 neutrons. What would its charge be? What would its mass be? It is equivalent to a helium-4 atom, so what would its symbol be? Symbol: 4 He 2 Example: Radium-226 →Radon He 2

Beta Radiation Beta particles are fast-moving electrons. What would its charge be? What would its mass be? Symbol: 0 β Example: Carbon-14 → nitrogen β

Gamma Radiation These are high-energy RAYS with no mass and no charge! Symbol: 0 γ 0 Gamma radiation USUALLY accompanies alpha or beta radiation. Example: uranium-238 → thorium He γ 2 0

Check Your Understanding P.107: 27 Complete the following reactions: – 60 Co → 60 Ni + ? – 241 Am → 237 Np + ? 95 93