Introduction to Mendeleev’sPeriodic Table of Elements

Mrs. Coyle

“The Elements” Song by

Tom Lehrer

• http://www.privatehand.com/flash/elements.html

Organizing Information

• What criteria can be used?

• Activity “Organizing Cards”

How are days organized?

Dmitri Mendeleev

Russian

1860’s

The Person Who Organized the Elements

Mendeleev

• Teacher at St. Petersburg University.

• Was working on a textbook for his Chemistry students.

• He organized the 63 elements known at the time.

His Criteria

• Increasing atomic mass.

• Physical and Chemical Properties.

Sodium’s Reaction with H2O

Potassium’s Reaction with H2O

Periodicity

• Reoccurrence (repetition) of properties at regular intervals.

Mendeleev’s Periodic Table

Like A Calendar

Mendeleev’s Predictions

• He left spaces on the table for undiscovered elements.

• He predicted the properties of elements that had not yet been discovered.

• How?

Example: Eka-aluminum

• He placed this undiscovered element below aluminum.

• He predicted the melting point to be low and the density to be 5.9g/cm3.

• It was later found and named Gallium with a density of 5.91g/cm3 and melting point of 29.7oC.

Gallium

A brief comparison of the modern periodic table to Mendeleev’s

• What is the main criterion used to organize elements in the modern periodic table?

Recap

• Mendeleev’s Criteria

• Periodicity

• Prediction