The periodic table isn't just a nice layout of information, the position of each element in the table provides further information about it. For example, we know gold (Au) is pretty a pretty good conductor of electricity. By looking at the other elements in its group (the column), we can guess that copper (Cu) and silver (Ag) are also good electrical conductors (in fact, some of the best).
Beyond that simple case, there are loads of other bits of information encoded in the position. The image on the Wikipedia article gives a good overview of some of the trends.