Lecture on Atomic Theory

Introduction to Atomic Theory

• Atomic Theory: Understanding elements and atoms, periodic chart.
• Elements: Defined by unique atomic numbers and properties.
• Originally 92 naturally occurring elements on Earth; now considered 96-98 due to new trace elements.

Structure of an Atom

• Atom: Smallest unit retaining properties of an element.
• Major Atomic Particles:
  • Protons: Positive charge, mass of 1 AMU.
  • Neutrons: No charge, mass slightly more than protons.
  • Electrons: Very small mass, negative charge.
• Quarks: Particles making up protons and neutrons.

Atomic Definitions

• Atomic Number: Number of protons in nucleus, defines the element.
• Atomic Mass: Total number of protons and neutrons.
• Atomic Weight: Average of atomic masses of an element's isotopes.

Isotopes

• Isotopes: Variants of elements with different neutron counts.
  • Approximately 1700 known isotopes; 264 are stable.
  • Stable Isotopes: Formed during Earth's formation, some with long half-lives.
• Radiogenic Isotopes: Created in labs or through events like nuclear reactions.

Chemical Bonding

• Bonding: Exchange or sharing of electrons to form compounds.
  • Covalent Bonding: Sharing electrons (e.g., water formation).
  • Ionic Bonding: Exchange of electrons to form ions (e.g., sodium chloride).
• Compounds: Formed through ionic and covalent bonds (e.g., calcite).

Hydrogen and Isotopes

• Hydrogen:
  • Most abundant element.
  • Atomic Number: 1, with isotopes hydrogen-1 and deuterium (hydrogen-2).
  • Tritium: Unstable isotope with a short half-life, results from nuclear reactions.

Application of Isotopes

• Isotopes used for scientific research and environmental studies (e.g., tracking water cycles).
• Carbon Isotopes: Carbon-12 and carbon-13 used to study ecological and geological changes.
• Nitrogen and Oxygen Isotopes: Used to explore natural processes.

Einstein's Mass Defect

• Mass Defect: Difference in calculated vs. actual atomic weight, explained by Einstein.
  • E=mc²: Mass-energy equivalence.
• Practical Implications: Understanding atomic binding energy.

Conclusion

• Introduction to isotopes and atomic theory.
• Example questions on isotopes for exams.
• Importance of isotopes in scientific research and applications.

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These notes summarize the main concepts and details from the lecture on atomic theory and isotopes. The goal is to provide a concise review for further study and understanding.