2: Background

The first Periodic Table dates back over 100 years! Ancient civilizations have used elements such as gold, silver, tin, copper, lead, and mercury for tools. But, it was not until 1869 when a Russian chemist named Dimitri Mendeleev created the first chart to organize the 63 elements discovered by this date. As the number of known elements grew, scientists began to recognize patterns in properties and to develop additional ways to classify them.