AP Chemistry Review - Unit 1: Atomic Structures and Properties

Introduction

• Presenter: Cara
• Focus: Atomic structures and properties in AP Chem curriculum
• Main Topics: Moles, molar mass, atomic mass, isotopes, Dalton’s laws, electron configurations, ions, periodic trends

Moles and Molar Mass

• Moles
  • Concept similar to dozen (12), mole represents Avogadro's number: 6.02 x 10^23
  • Converts atomic mass units (amu) to grams
  • Example: 1 molecule of nitrogen = 14 amu, 14 grams of nitrogen = 1 mole
• Molar Mass
  • Expressed as grams per mole (mass over mole)
  • Example Calculation: 25 grams of calcium / 40.08 grams per mole = 0.624 moles
• Conversions
  • Moles to molecules using Avogadro's number

Isotopes

• Definition: Atoms of the same element with different numbers of neutrons (different masses)
• Average Atomic Mass
  • Weighted average of isotopes based on their abundance
  • Calculation Example: Carbon isotopes (Carbon-12 and Carbon-13) with abundance 98.9% and 1.1%

Mass Spectrometry

• Measures charge to mass ratio of ions
• Process: Ionization, acceleration through electric field, deflection in magnetic field
• Data: Plot showing relative abundance against mass/charge ratio

Dalton’s Laws

• Atoms are the smallest unit of matter
• Mass is conserved in reactions
• Law of constant composition: Compounds have a fixed ratio of atoms

Compounds and Mixtures

• Compounds: Pure substances made of two or more elements
• Mixtures: Combination of compounds not chemically bonded
• Chemical Formulas
  • Structural, chemical, empirical

Ions and Ionic Compounds

• Ions
  • Atoms gain/lose electrons to form ions (cations are positive, anions are negative)
• Ionic Bonds
  • Formed between cations and anions, example NaCl
• Naming Ionic Compounds
  • Transition metals: Use Roman numerals to denote charge (e.g., Iron II chloride)

Electron Configurations

• Quantum Numbers: Describe orbitals
  • Principal (n), azimuthal (l), magnetic (m), spin (s)
  • Orbitals: s, p, d, f with specific shapes and energy levels
• Filling Order: Aufbau principle, Hund's rule
• Periodic Table as a Guide
  • Zones for s, p, d, f orbitals
  • Noble gas notation for simplification
• Exceptions: Half-filled and fully-filled d sublevels (e.g., Chromium, Copper)

Periodic Trends

• Atomic Radii: Decreases across a period, increases down a group
• Ionization Energy: Energy required to remove electrons
• Electron Affinity: Energy change when gaining an electron
• Electronegativity: Atom's ability to attract electrons in a bond
• Metallicity: Increases towards Francium

Conclusion

• Understanding atomic structure and periodic trends is essential for mastering AP Chemistry
• Presenter encourages feedback and suggestions for future reviews