AP Chemistry Unit 1 Review: Atomic Structure and Properties

Introduction

• Presenter: Jeremy Krug
• Focus: Key concepts from AP Chemistry Unit 1, covering atomic structure and properties.

1. Moles and Grams Conversion

• Concept: Convert between moles and grams using atomic mass.
• Example:
  • Convert 10.00 grams of CO₂ to moles:
    • Use atomic masses: CO₂ = 44.01 g/mol (12.01 + 16.00 + 16.00)
    • Calculation: 10.00 g x (1 mol/44.01 g) = 0.2272 mol
• Particles to Moles:
  • Avogadro’s number: 6.022 x 10²³ particles/mol
  • Example: Convert 0.2272 mol CO₂ to molecules = 1.368 x 10²³ molecules

2. Mass Spectrum Interpretation

• Concept: Analyze mass spectrum graphs to determine isotopic abundance.
• Example:
  • Element with isotopes of 107 amu and 109 amu
  • Abundance: 107 amu (52%) and 109 amu (48%)
  • Average Atomic Mass ≈ 108 amu, identifying the element as Silver (Ag)

3. Empirical Formula Determination

• Definition: Simplest whole number ratio of elements in a compound.
• Example:
  • Given: 40.05% sulfur, 59.95% oxygen
  • Convert to moles and divide by smallest mole value
  • Empirical formula: SO₃
  • Law of Definite Proportions: Consistent composition ratios

4. Mixtures vs. Pure Substances

• Concept: Analyze samples for purity; identify impurities.
• Example:
  • Potassium chloride sample with impurities
  • Focus on common ion (chloride) to determine purity
  • Percent mass calculation

5. Electron Configurations

• Concept: Write and interpret electron configurations.
• Example:
  • Scandium: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹
  • Valence electrons: Electrons in the outermost shell
• Coulomb’s Law: Describes force between charged particles
  • Charge and distance influence attraction

6. Photoelectron Spectroscopy (PES)

• Concept: Identify elements using PES graphs.
• Example:
  • Label peaks with sublevels (1s, 2s, 2p, etc.)
  • Relative peak heights correspond to electron numbers

7. Periodic Table Trends

• Trends:
  • Ionization energy and electronegativity increase right and up
  • Atomic radius increases left and down
• Explanations:
  • Effective nuclear charge influences horizontal trends
  • Distance of valence electrons influences vertical trends

8. Valence Electrons and Ionic Compounds

• Concept: Number of valence electrons influences ion formation
• Group Patterns:
  • Group 1: +1 charge
  • Group 2: +2 charge
  • Group 17: -1 charge
• Examples:
  • MgCl₂ (Magnesium Chloride): +2 and -1 charges
  • Al₂S₃ (Aluminum Sulfide): +3 and -2 charges

Conclusion

• Summary of key Unit 1 concepts related to atomic structure and properties.
• Encouragement to explore further resources for comprehensive understanding.