The Periodic Table

The first periodic table was invented by a man named Dimitri Mendeleev (1834-1907) who was the first to arrange the elements by their increasing atomic mass.

It all started while he was studying with flashcards and he noticed a pattern in the elements, so he put the elements most similar side by side and in columns. This produced a periodic table that worked but had blanks in it, simply because there were no know elements with the appropriate properties at the time.

The second periodic table was invented by a young British physicist named Henry Moseley (1887-1915). He figured out an elements nuclear charge and called it its atomic number. His periodic table was arranged by atomic number just as the periodic table is today.

Todays periodic is arranged in seven horizontal rows called periods (arranged in increasing atomic number). The vertical rows are called groups or families and there are 18 groups. The types of elements in the groups are, starting from the left going to the right are Alkali Metals, Alkaline Earth Metals, Transition Metals, Aluminum, Carbon, Nitrogen, Oxygen, Halogens, Noble Gases. Elements with similar chemical properties are all in the same group; this is due to the Periodic Law: when the elements are arranged in order of increasing atomic number, there is a periodic pattern in their physical and chemical properties.

Oh and here is a really cool periodic table...... http://i.imgur.com/5FVE8.jpg