Development of the periodic table
The Early Periodic Table
The periodic table of the elements developed as an attempt to classify the elements. It arranges them in a pattern according to their properties. Early versions of the periodic table failed to take account of the fact that not all the elements were known at the time. Mendeleev's table took account of unknown elements, and so provided the basis for the modern periodic table.
The Modern Periodic Table
The group that an element is in is determined by its atomic (proton) number. The number of electrons in the highest energy level of an atom determines its chemical…