Unstable Nuclei and Radioactive Decay

1
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.

2
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.

3
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

4
Types of Radiation

• Three-Tab Foldable
• Alpha radiation
• Beta radiation
• Gamma radiation

5
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 4He
• 2
• Example Radium-226 ?Radon-222 4He
• 
  2

6
Beta Radiation

• Beta particles are fast-moving electrons.
• What would its charge be?
• What would its mass be?
• Symbol 0ß
• -1
• Example Carbon-14 ? nitrogen-14 0ß
• 
  -1

7
Gamma Radiation

• These are high-energy RAYS with no mass and no
  charge!
• Symbol 0?
• 0
• Gamma radiation USUALLY accompanies alpha or beta
  radiation.
• Example uranium-238 ? thorium-234 4He 2 0?
  
• 2 0

8
Check Your Understanding

• P.107 27
• Complete the following reactions
• 60Co ? 60Ni ?
• 27 28
• 241Am ? 237Np ?
• 95 93