The periodic table
In the periodic table the elements are arranged in rows and columns, each row is called a period and each column is called a group.
In each group is a group of simalar elements, eg. group 1 has highly reactive metals and group 8 has non reactive gases.
All of the elements are in groups apart from the transition metals (the block in the middle), the lanthanide series and the actinide series.
You can find out how many protons, neutrons and electrons an element has by looking at it's proton number and relative atomic mass.