Lecture Notes: Crash Course Chemistry - The Periodic Table of Elements

Introduction

Background:
- Born in Siberia; family faced hardships due to father's blindness and death.
- Mother opened a glassmaking factory to support his education.
- Factory burned down; mother took Mendeleev on a 1200-mile journey to Moscow, then St. Petersburg.
- He was eventually accepted to a university in St. Petersburg.
- Despite hardships, including his mother's death, he pursued science passionately.

Time Period: 1860s
Known Elements: About 60, with known atomic weights.
Insight: Noticed periodic relationships between elements beyond simple atomic weight order.

Approach:
- Arranged elements by atomic weights initially.
- Observed repeating patterns (periodicity) in elements' properties.
- Gaps in the table indicated undiscovered elements.
- Predicted properties of undiscovered elements accurately.

Groups Identified by Mendeleev:
- Alkali Metals: Highly reactive, stored in inert gases/oil.
- Alkaline Earth Metals: Less reactive, form cations with two positive charges.
- Transition Metals: Conductive, malleable, mostly metals like iron and gold.
- Halogens: Reactive gases, form anions with negative charges.
- Noble Gases: Non-reactive, discovered later.
- Lanthanides & Actinides: Similar metals, hard to separate, discovered later.

Unique Aspects:
- Obsessive commitment to his research.
- Recognized the broader implications of periodicity.
Beliefs:
- Saw potential divine patterns in chemistry.

Challenges with Current Table:
- Lanthanides and actinides should be integrated into the main table.
- Ideal table would wrap around, connecting elements like fluorine and sodium.

Impact: Mendeleev's table was a guide for future discoveries in chemistry.
Future Episodes: Next episode will discuss the electron's role in periodicity.