1The periodic tableDEVELOPMENT OF I

1
The periodic table
DEVELOPMENT OF IDEAS
METALS AND NON-METALS
We now know of the existence of over one hundred elements. A century
ago, more than sixty of these were already known, and naturally
attempts were made to relate the properties of all these elements in
some way. One obvious method was to classify them as metals and
non-metals; but this clearly did not go far enough.