Mass Spectrometry and Identifying Elements

Overview

• Mass spectrometry (or mass spectroscopy) is a technique to determine the atomic masses of isotopes in a substance.
• It helps in identifying pure elements by analyzing their atomic masses and isotopes.

Given Data

• Mass spectrum for a pure element is provided.
  • 82% of sample: atomic mass = 88 universal atomic mass units (u)
  • 7% of sample: atomic mass = 87 u
  • 10% of sample: atomic mass = 86 u
  • 1% of sample: atomic mass = 84 u

Calculation of Average Atomic Mass

• Weighted Average Formula:
  • Average Atomic Mass = (0.82 * 88) + (0.07 * 87) + (0.10 * 86) + (0.01 * 84)
• Since 82% is the highest weight, the average atomic mass will be close to 88 but slightly lower due to other isotopes.

Estimation and Element Identification

• Estimate average atomic mass slightly less than 88.
• Comparing with elements:
  • Yttrium: 88.91 (Rejected, isotopes should be below 88)
  • Strontium: Looks promising, slightly less than 88
  • Rubidium: Too low, much less than 88
• Conclusion: Based on the estimated average atomic mass, the mystery element is Strontium.