🔎 🌎 EN Class code 🔑 Log in Subscription

Mendeleev (Historical) HTML5


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

Select the time-period you want to select.

Click an element to read its name.

Learning goals

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

Learn more

Each element in the table is represented by a symbol and by two numbers, the first  being the atomic number (number of protons) and the second the atomic weight (number of protons + neutrons). The…

Subscribe now to read more about this topic!