Unit 6 - Periodic Table
All matter is composed of elements, of which there are about 110 different kinds. A few elements have been known for thousands of years, including copper, silver, and gold. Yet only 13 elements had been identified by the year 1700. As more and more elements were discovered, scientist needed a way to orgainize them. Chemists used the porperties of the elements to sort them into gorups and the periodic table was established.
