Average Atomic Mass Lecture Notes

Introduction to Average Atomic Mass

• Topic: Average atomic mass and isotopes
• Analogy: Using M&Ms to demonstrate concepts
• Objective: Determine the average mass that goes on the periodic table

Isotopes and M&Mium

• Different isotopes of an element (M&Mium)
• Example: Comparing bigger isotopes vs. smaller ones
• Process involves calculating average mass due to inconsistencies in candy size

Weighing the Isotopes

1. Weighing Methodology

   • Use of a balance to measure mass in grams (G)
   • Importance of using a weigh boat to avoid contamination
   • Taring the balance to exclude the weigh boat's mass

2. Mass Measurements for Plain M&Ms:

   • Yellow: 0.96 grams
   • Blue: 0.86 grams
   • Orange: 0.86 grams
   • Brown: 0.91 grams
   • Red: 0.82 grams

3. Mass Measurements for Peanut M&Ms:

   • Yellow: 3.62 grams
   • Blue: 3.15 grams
   • Orange: 2.51 grams
   • Red: 3.08 grams
   • Green: 2.65 grams

4. Mass Measurements for Skittles:

   • Orange: 1.14 grams
   • Purple: 1.12 grams
   • Green: 1.10 grams
   • Red: 1.07 grams
   • Yellow: 1.13 grams

Calculating Average Mass

• To find the average mass:
  1. Add all individual masses together
  2. Divide the total by the number of samples (5)
• Example: Average calculation for each type of candy
  • Plain, Peanut, Skittles each calculated separately

Percent Abundance Calculation

• Definition: Percent = (part/whole) x 100
• Formula for Percent Abundance:
  • For Plain: (Number of Plain M&Ms / Total M&Ms) x 100
  • For Peanut: (Number of Peanut M&Ms / Total M&Ms) x 100
  • For Skittles: (Number of Skittles / Total M&Ms) x 100

Overall Average Atomic Mass Calculation

• Average Atomic Mass Equation:
  • (Percent Abundance of Plain x Average Mass of Plain) +
  • (Percent Abundance of Peanut x Average Mass of Peanut) +
  • (Percent Abundance of Skittle x Average Mass of Skittle)
  • Divide total by 100 to obtain average atomic mass of M&Mium

Error Analysis in Experiment

• Importance of error evaluation in scientific experiments
• Determining Error:
  • Weigh all candies together for total mass
  • Calculate accepted value (average weight of candy)
  • Compare experimental value (from M&M averages) to accepted value
  • Formula: Percent Error = (|Experimental Value - Accepted Value| / Accepted Value) x 100

Conclusion

• Importance of showing work in calculations
• Review and practice error analysis for further understanding
• Encouragement for students to engage with the activity and calculations

Good Luck!

• Reminder to enjoy the experiment and learning process.