Basics of Elements and Atomic Structure

Sep 18, 2024

Lecture Notes

Introduction to Substances and Elements

  • Humans have observed different substances with varying properties for thousands of years.
    • Substances reflect light differently, exist in different states (solid, liquid, gas), and react with each other under certain conditions.
  • Examples of substances:
    • Carbon in graphite form
    • Lead
    • Gold
  • Substances can be broken down into smaller units, leading to the question of the smallest unit retaining the properties of the substance.

Elements and Atoms

  • Elements are pure substances with specific properties and reactions.
    • Carbon, Lead, Gold are elements.
    • Water, historically considered an element, is made of oxygen and hydrogen.
  • Periodic Table of Elements lists all known elements.
    • C for Carbon, O for Oxygen, N for Nitrogen, Si for Silicon, Au for Gold, Pb for Lead.
  • The smallest unit of an element retaining its properties is the atom.
    • Examples: carbon atom, gold atom, lead atom.

Properties of Atoms

  • Atoms are incredibly small; approximately 1 million carbon atoms span the width of a human hair.
  • Atoms are the building blocks of elements and consist of even more fundamental particles.

Protons, Neutrons, and Electrons

  • Protons define the element by their number.
    • Atomic number = number of protons.
    • Hydrogen has 1 proton, Helium has 2, Carbon has 6, and so on.
  • Atoms consist of:
    • Protons (positive charge)
    • Neutrons (neutral)
    • Electrons (negative charge)
  • Nucleus of an atom contains protons and neutrons.
    • Example: Carbon-12 has 6 protons, 6 neutrons.

Atomic Structure and Electron Behavior

  • Electrons move around the nucleus, can be conceptualized as orbiting or buzzing.
  • Electrons are bound to nucleus due to attraction between unlike charges (positive proton, negative electron).
  • Neutrons affect properties but are neutral in charge.

Chemistry and Reactions

  • Chemistry involves interactions of electrons between atoms.
    • Atoms may lose electrons resulting in a net charge.
    • Electron configurations influence how atoms react or bond.

Conclusion

  • Understanding atomic structure and elements is fundamental to chemistry.
  • Atoms are composed of protons, neutrons, and electrons which determine the properties and interactions of elements.