CH. 13 | Nuclear Reactions

Nuclear radioactivity

Spontaneous emission of particles or energy from an unstable nucleus

3 Types of Radioactive decay

• Alpha decay

• Beta decay

• Gamma decay

Nuclear equations

Atomic number = number of protons in nucleus

Isotopes: same atomic number; different number of neutrons

Nuclear reactions

• Represented by balanced equations

• Charge conserved

• Mass number conserved

Nature of the Nucleus

Strong nuclear force

• Binds protons and neutrons

• Very short ranged, less than

• Overcomes proton-proton Coulomb repulsion

Nuclear shell model

• Nucleon quantum energy levels

• Maximum stability for nucleon number = 2 , 8 , 20 , 28 , 50 , 82 , or 126
  → Filled + half-filled orbitals are more stable

Band of stability

Generalizations: Nuclear Stability

Types of Radioactive Decay

Alpha emission

• Expulsion of helium nucleus

• Least penetrating: stopped by paper

• Beta emission

Beta emission

• Expulsion of an electron

• More penetrating: 1 cm of aluminum

Gamma decay

• Emission of a high-energy photon

Most penetrating: 5 cm of lead

Cont…

Half life

Measurement of Radiation

Ionization counters

• Detect ions produced by radiation

• i.e., Gelger counter

Scintillation counters

• Rely on flashes of light produced as radiation strikes a phosphor

• Zinc sulfide

Radiation Units

Nuclear Energy

Nuclear Fission

Nuclear Fusion