Atomic Mass and Weighted Averages

Introduction

• Atomic Mass: A key characteristic of elements.
  • Sometimes referred to by other names.
• Importance: Determines the mass of elements like Copper, Oxygen, Sulfur.

Location on Periodic Table

• Found beneath the element's symbol.
• Atomic mass is an average of different atoms' masses.

Weighted Averages

• Definition: A special kind of average that considers the abundance of each component.
• Different from regular averages learned in math.

Analogy: Cars

• Model Example: Lemona cars (GX and GXL).
  • GX: Blue, lighter weight, common features.
  • GXL: Red, heavier, luxury features.
• Comparison to Isotopes: Different models are like isotopes.
  • Isotopes have the same number of protons but different neutrons.

Calculating Regular Averages

• Example Cars:
  • GX: 4000 pounds
  • GXL: 5000 pounds
• Regular Average: (4000 + 5000) / 2 = 4500 pounds.

Importance of Weighted Averages

• Takes into account the abundance of each model or isotope.
• Example:
  • 95% GX and 5% GXL.
  • Weighted Average: (4000 * 0.95) + (5000 * 0.05) = 4050 pounds.
• Result: Closer to the weight of the more abundant model (GX).

Application to Atomic Mass

• Copper Isotopes: Copper 63 and Copper 65.
  • Copper 63: 63 amu, 69% abundance.
  • Copper 65: 65 amu, 31% abundance.
• Weighted Average Calculation:
  • Copper 63: 63 * 0.69 = contribution
  • Copper 65: 65 * 0.31 = contribution
  • Total: 63.62 amu.

Conclusion

• Atomic Mass on the periodic table reflects this weighted average.
• Note: Real atomic mass values may include more precise numbers than used in examples.
• Understanding weighted averages helps comprehend atomic mass on the periodic table.

Further Study

• Practice problems on atomic mass and weighted averages are available in other videos.