Overview
This lecture discusses Dmitri Mendeleev's creation of the periodic table, highlighting his predictive genius and the impact of his scientific achievements.
The Periodic Table and Its Origins
- The periodic table is a widely recognized scientific tool organized by Dmitri Mendeleev.
- Mendeleev was not the first to list or group elements by properties.
- Earlier attempts at arranging elements did not achieve the predictive power of Mendeleev's table.
Mendeleev's Scientific Insight
- Mendeleev's genius lay in leaving intentional gaps for undiscovered elements.
- He used the properties of surrounding elements to predict the properties of missing ones.
- For the gap later known as "eka-aluminum," he predicted atomic weight, physical state, appearance, conductivity, malleability, melting point, and density.
Verification of Predictions
- Gallium, discovered by Paul Emile Lecoq de Boisbaudran, matched Mendeleev's predictions for eka-aluminum.
- Gallium's atomic weight (69.72) and density (5.9 g/cm³) closely matched Mendeleev's estimates.
- Other elements predicted included scandium, germanium, rhenium, and technetium (formerly eka-manganese).
Mendeleev's Legacy
- Mendeleev died in 1907 without a Nobel Prize.
- In 1955, element 101 was discovered and named Mendelevium in his honor.
- Only 15 scientists have elements named after them, highlighting the rarity of this recognition.
Key Terms & Definitions
- Periodic Table — An organized chart of chemical elements arranged by atomic number and similar properties.
- Atomic Weight — The average mass of atoms of an element, measured relative to hydrogen.
- Eka-aluminum — Mendeleev’s predicted element one place beyond aluminum, later discovered as gallium.
- Technetium — Rare element predicted as eka-manganese, first synthesized in 1937.
Action Items / Next Steps
- Review properties and trends of the periodic table’s groups and periods.
- Read more about the discovery and confirmation of predicted elements.