CHEMISTRY  SSS2 First Term

WEEK 1

Periodic Table I

Performance objectives

Students should be able to:

1. State the periodic law.
2. Arrange common elements into groups and periods.
3. Identify at least two characteristic features of each of the families of these elements.

Content

Historical development of the periodic table         

In chemistry, classification of elements began with Lavoisier, whose classification was essentially into metals and non-metals. Between 1869-1871, a Russian scientist called Dmitri Mendeleev devised the periodic law. He developed the periodic law, which states that the properties of an element varied periodically with their relative atomic masses. He arranged elements in increasing order of relative atomic mass. This, elements having similar properties kept on reoccurring t regular intervals or periods, forming families of relative elements.

    Mendeleev's periodic table had.... View More