Lecture on Newlands' Law of Octaves

Introduction

• Lecture Objective: Discussion on the predictive classification of elements for 10th-grade science students.
• Previous Lecture: Discussion on Dobereiner's Triads.

Newlands' Law of Octaves

• Newlands: An English scientist in 1866 who arranged elements in order of increasing atomic mass.
• Meaning of Octave: Group of eight.

Newlands' Method

• Principle: Every first and eighth element have similar chemical properties.
• Examples:
  • Lithium and Sodium
  • Beryllium and Magnesium
  • Fluorine and Chlorine

Limitations and Problems

• Limited to Calcium: Newlands' law was valid only up to calcium.
• Discrepancies:
  • Cobalt, nickel, etc., included in the halogen group.
  • Not all pairs had similar chemical properties.
• 56 Boxes: It was impossible to fit all elements.

Conclusion

• Success and Failure: After initial success, Newlands' law of octaves failed.
• Next Step: Study of Mendeleev's theory.

Closure

• Newlands' method was effective to a limit but not entirely successful.
• The next lecture will discuss Mendeleev's methods.

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