Crash Course Chemistry: The Periodic Table

Introduction

• Hosted by Hank Green
• Focus: The periodic table of elements
  • Described as an information-dense catalog of atoms
  • Considered one of the crowning achievements of human thought

The Story of Dmitri Mendeleev

• Background

  • Born in Siberia to a large family
  • Father was a professor who went blind; family faced destitution
  • Mother reopened a glassmaking factory to support the family
  • Factory burned down; mother saw potential in Dmitri's scientific mind
  • Travelled 1200 miles to Moscow, then 400 miles to St. Petersburg
  • Accepted into the university at St. Petersburg; mother died shortly after

• Scientific Contributions

  • Became a prominent chemist, studying elements and their properties
  • In the 1860s, about 60 elements were known, and Mendeleev sought to organize them
  • Initially sorted elements by atomic weight, noticed periodic relationships
  • Key insight: Repetition of characteristics every seven elements
  • Realized some elements were missing and inserted gaps in his periodic table
  • Predicted properties of undiscovered elements, some confirmed later

Characteristics of the Periodic Table

• Alkali Metals

  • Soft, shiny, extremely reactive
  • Form positive ions (cations), require storage in inert gases/oil

• Alkaline Earth Metals

  • Reactive but less so than alkali metals
  • Form cations with two positive charges

• Transition Metals

  • Middle section of the table
  • Less reactive, good conductors of heat and electricity
  • Malleable and important in chemistry

• Halogens

  • Reactive gases forming negative ions (anions)
  • Love to react with alkali and alkaline earth metals

• Noble Gases

  • Unreactive, discovered after Mendeleev's table

• Lanthanides and Actinides

  • Separate island on the table, similar metals difficult to separate

Mendeleev's Legacy and Impact

• Mendeleev's periodic table was more comprehensive than others at the time
• Obsessed with perfection and the cosmic importance of periodicity
• Believed the periodic table held divine patterns
• Many contemporaries published similar theories, but Mendeleev's was most impactful

The Evolution of the Periodic Table

• Continual development and improvement
• Alternative models exist, such as a cylindrical periodic table
• Current table could be reimagined for better physical representation
• Mendeleev's table set the stage for future discoveries, including electrons

Conclusion

• Mendeleev's work provided a framework for understanding chemical properties and predicting undiscovered elements
• Modern periodic table remains a vital tool in chemistry

This episode was created by Hank Green and the Crash Course team. For further questions, feel free to explore the comments and resources provided by the Crash Course Chemistry series.