Lecture Notes: Basics of Chemistry

Atoms and Their Composition

• Atoms: Basic units of matter
  • Made of a core (protons + neutrons) and electrons
  • Number of protons defines the element
• Electron Shells: Multiple layers around the nucleus
  • Valence Electrons: Electrons in the outermost shell

Periodic Table

• Lists all elements
• Groups: Vertical columns with same number of valence electrons
  • Main group elements' valence electrons equal group number (1-8)
• Periods: Horizontal rows with same number of electron shells
  • Increases top to bottom

Chemical Bonds

• Valence Electrons: Drive chemical behavior
• Types of Bonds:
  • Covalent: Sharing of electrons
  • Ionic: Transfer of electrons
  • Metallic: Delocalized electrons in metal grid
• Electronegativity: Measure of an atom's pull on electrons
  • Increases bottom left to top right in periodic table

Molecules and Compounds

• Molecule: Two or more atoms bonded
• Compound: Molecule with at least two different elements
• Isomers: Molecules with same formula but different arrangement

States of Matter

• Solid: Particles packed tightly, fixed structure
• Liquid: Particles move freely, fixed volume
• Gas: Particles move freely, fill volume
• Plasma: Ionized gas at high temperatures

Chemical Reactions

• Types: Synthesis, decomposition, single and double replacement
  • Driven by energy reduction to stable states
• Stoichiometry: Ratios based on conservation of mass
• Activation Energy: Energy needed to start a reaction
• Catalysts: Lower activation energy without being consumed

Thermodynamics

• Enthalpy (H): Internal energy/heat content
• Entropy (S): Measure of disorder
• Gibbs Free Energy (G): Combines enthalpy and entropy to determine spontaneity
  • Exergonic: Spontaneous, releases energy
  • Endergonic: Non-spontaneous, absorbs energy

Acids, Bases, and pH

• Acids: Proton donors
• Bases: Proton acceptors
• pH Scale: Measures acidity/basicity
  • pH and pOH always add up to 14

Quantum Mechanics and Electron Configuration

• Quantum Numbers: Describe electrons
  • N: Principal quantum number (shell)
  • L: Subshell shape
  • ML: Orbital orientation
  • MS: Electron spin
• Aufbau Principle: Order of filling electron shells
• Electron Configuration: Describes electron arrangement

Key Terminologies

• Valence Electrons, Electronegativity, Isomers, Ions
• Lewis Dot Structure, Covalent and Ionic Bonds
• Molecular Formula, Intermolecular Forces (IMFs), Hydrogen Bonds, Van der Waals Forces

These notes summarize the key concepts discussed in the lecture on chemistry basics, including atomic structure, periodic table organization, chemical bonding, states of matter, and foundational principles of quantum mechanics.