Fundamentals of Atoms and Chemistry

Sep 19, 2024

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Lecture Notes: Introduction to Atoms and Chemistry

Atoms and Elements

  • Atoms: Made of a core (protons and neutrons) and electrons.
    • Core determines different elements based on the number of protons.
  • Elements: Listed on the periodic table, categorized by groups and periods.
    • Group number = Number of valence electrons (1-8, except He with 2).
  • Valence Electrons: Electrons in the outermost shell, crucial for chemical reactions.

Structure and Behavior of Atoms

  • Electron Shells: Multiple shells with electrons; valence electrons are in the outermost shell.
  • Periodic Table: Organized by:
    • Groups: Same number of valence electrons = similar chemical behavior.
    • Periods: Same number of electron shells.

Chemical Bonds and Reactions

  • Types of Bonds:
    • Covalent Bonds: Sharing of electrons; low potential energy state.
    • Ionic Bonds: Transfer of electrons; formation of cations and anions.
    • Metallic Bonds: Delocalized electrons, properties of metals.
  • Electronegativity: Varies across the periodic table; affects bond type.
  • Intermolecular Forces (IMFs): Include hydrogen bonds, Van der Waals forces.

Molecules and Compounds

  • Molecules: Atoms bonded together.
  • Compounds: Molecules with at least two different elements.
    • Compounds have different properties from their constituent elements.
  • Isomers: Same molecular formula, different structure.

States of Matter and Energy

  • States: Solid, liquid, gas, and plasma.
  • Temperature & Entropy:
    • Temperature: Average kinetic energy.
    • Entropy: Amount of disorder; high in gases, low in solids.
  • Phase Transitions: Depend on temperature and pressure.

Chemical Reactions

  • Types of Reactions: Synthesis, decomposition, single and double replacement.
  • Stoichiometry: Ensures conservation of mass in reactions.
  • Moles: Measure of particles, useful for stoichiometry.
  • Activation Energy: Energy required to start a reaction.
  • Catalysts: Lower activation energy, reusable.

Acids, Bases, and pH

  • Acid-Base Chemistry:
    • Acids donate protons, bases accept them.
    • Amphoteric substances can act as both.
  • pH Scale: Measures acidity (lower = more acidic).

Redox Reactions

  • Redox: Reduction (gain of electrons) and oxidation (loss of electrons).
  • Oxidation Numbers: Help track electron flow.

Advanced Atomic Theory

  • Quantum Mechanics:
    • Electrons described by quantum numbers (N, L, ML, MS).
    • Explain electron shells and subshells.
  • Electron Configuration: Order of filling orbitals.

Practical Chemistry

  • Mixtures: Homogeneous (solutions) and heterogeneous (suspensions).
  • Colloids and Emulsions: Intermediate mixtures, like milk.
  • Chemical Equilibrium: Balance in reversible reactions.

Each section provides foundational knowledge for understanding more complex chemical concepts and phenomena. Review these notes to reinforce your grasp on basic chemistry principles and the behavior of atoms and molecules.