The periodic table is a way of organizing known elements into groups with
similar properties. Mendelev was a Russian scientist who was first to
recognise that elements can be grouped together according to atomic mass.
The modern periodic table has elements arranged in order of electronic
configuration. The table is divided into groups(columns) and periods(rows). Elements in the same group display similar chemical properties and trends emerge as we go along a period and down a group.
All elements in a particular group share similar chemical properties. All
elements in group 1 are very reactive metals, with the exception of hydrogen
gas. These metals react readily with other compounds and elements to give away some of their outer shell (valence) electrons. These metals react with water to produce hydrogen gas. Click on the blue writing below to see the reactions.