Nuclear Chemistry Flashcards

Nuclear Chemistry

Basics

• Nuclear chemistry studies reactions involving changes in the nucleus of an atom.
• Focuses on protons and neutrons, not electrons.
• Unstable nuclei are radioactive and decay spontaneously by emitting particles and energy.
• Elements with atomic # > 83 are radioactive.
• Stable nuclei are not radioactive.
• Transmutation: one element changes into another through radioactive decay.

Types of Radiation

• Alpha (\alpha): charge of +2, mass of 4.
• Beta (\beta): charge of -1, mass of 0.
• Gamma (\gamma): no charge, no mass.

Characteristics of Radiation

• Alpha (\alpha) emission:
  • Greatest change in atomic number due to +2 charge.
  • Greatest change in mass number due to mass of 4.
  • Stopped by thin paper or air.
• Beta (\beta) emission:
  • Can travel through paper but stopped by aluminum.
• Gamma (\gamma) emission:
  • Least change in atomic number due to no charge.
  • Least change in mass number due to no mass.
  • Most dangerous outside the body.
  • Travels through thick lead.

Symbols and Shielding

• Alpha particle: \alpha or ^4_2He, shielded by paper/plastic.
• Beta particle: \beta^- or ^0_{-1}e, shielded by plastic/metal foils.
• Gamma radiation: \gamma, shielded by heavy lead/concrete.
• Neutron: ^1_0n, shielded by water/heavy metal.
• Positron: ^0_{+1}e or \beta^+

Penetrating Power

• Alpha < Beta < Gamma, neutron

Natural Transmutations

• Unstable nucleus emits alpha, beta, or positron.

• Total mass number and atomic number must be the same on both sides of the reaction.

• Example:

  • Alpha Decay of Radium-226: \begin{aligned} ^{226}{88}Ra \rightarrow ^42He + ^{222}_{86}Rn \end{aligned}
  • Beta Decay of Lead-214: ^{214}{82}Pb \rightarrow \ ^{0}{-1}e + ^{214}_{83}Bi