L4: Half Life

• HALF LIFE

  • time required for half of the atoms of a radioactive substance to become disintegrated
• half life (t 1/2) = ln2 / k
• k = ln2 / t 1/2 (half life)
• DECAY CONSTANT

  • probability per unit time that any individual nucleus will decay
• NUMBER OF REMAINING NUCLEI

  • N1 = N0e^(-kt)