Ages

Introduction

Summary

In 1869 the Russian chemist D. I. Mendeleev discovered that pure chemical elements (containing a single kind of atom) could be classified in a table,  in families,  according to the number of protons in their nuclei. This number, called the atomic number, increases from top to bottom and from left to right on this table. The elements arranged in the same column have similar chemical properties.

This animation shows which elements were known at different periods of history:

1700 (the death of Boyle)

1787  (Lavoisier)

1871 (Mendeleev)

At the present time

Goals

• To show how the rate of discovery of new elements has increased during the last several centuries.

Features

Click on the time-period you want to select.

Roll over the elements to see their names.

Student sheet

You have to subscribe to access the student sheet!

Tags

Mendeleev chemistry elements Lavoisier Boyle discovery