Unstable Isotopes

Basic Definitions

Isotopes: Atoms of a single element that have the same number of protons but vary in their number of neutrons.

• They reside at the same position on the periodic table due to their identical atomic numbers.
• This concept is significant in disciplines such as nuclear chemistry and environmental science.

Characteristics of Isotopes

• Isotopes share positions on the periodic table because of the identical number of protons.
• Their chemical behaviour is largely the same due to sharing the same electron configuration.

Isotope Stability

Stable Isotopes

• Stable Isotopes: These do not undergo radioactive decay.
  • They are applied in medicine and environmental monitoring because of their enduring stability.

Unstable Isotopes (Radioisotopes)

• Unstable Isotopes: These emit radiation as they decay.
• Example: Carbon-14 decays into stable Nitrogen-14.

Neutron-to-Proton Ratio and Isotope Stability

• The Neutron-to-Proton (n/p) Ratio is crucial for assessing the stability of an isotope.
• The Zone of Stability denotes naturally stable isotopes based on their n/p ratios.

Introduction to Radioactivity

• Radioactivity entails the release of energy and particles as atoms transition from an unstable state to a stable state.
  • Instability often results from an imbalance between protons and neutrons.

Half-Life:

• The period required for half of the atoms in a radioactive sample to decay.
• It is essential in areas such as archaeology and medicine.

Decay Processes in Unstable Isotopes

Alpha, Beta, and Gamma Decay

Alpha Decay

• Expulsion of an alpha particle (2 protons, 2 neutrons).
  • Example: Uranium-238 decays to Thorium-234.

Beta Decay

• Involves the conversion of a neutron into a proton, releasing a beta particle.
  • Example: Carbon-14 converts to Nitrogen-14.

Gamma Decay

• Emission of gamma rays, which typically occur after alpha or beta decay.
  • Utilised in medical imaging due to non-ionisation of mass.

Types of Radiation

Alpha Radiation

• Composed of 2 protons and 2 neutrons.
• Possesses a large mass and a positive charge.
• Exhibits low penetration power; can be stopped by paper.

Beta Radiation

• Comprises high-speed electrons or positrons.
• Has medium penetration power and is suitable for medical diagnostics like PET scans.

Gamma Radiation

• Composed of high-energy photons without mass or charge.
• Exhibits high penetration power, requiring dense materials for shielding; widely applied in cancer treatment.

Safety Considerations and Shielding

• Protective Measure: Implement appropriate shielding and minimise exposure time.

Balanced Nuclear Reactions

Studying nuclear reactions reveals fundamental differences from chemical reactions, concentrating on transformations within the atomic nucleus.

Types of Nuclear Reactions

Alpha, Beta, and Gamma Processes

• Adheres to principles of conservation of mass and atomic numbers in reactions.
• Accurate calculation of daughter nuclei post-transitions is crucial.

Diagrammatic Explanations

• Alpha Decay: Uranium-238 transitions to Thorium-234.
• Beta Decay: Carbon-14 transitions to Nitrogen-14.
• Offers comprehensive visuals detailing each decay process.

Illustrative Examples

• Decay Chain of Uranium-238: Provides insights into transformation into stable lead through multiple decay phases.

• Geiger Counter: Essential device for monitoring nuclear activity around isotopes.