The Periodic Table is simply a way of displaying chemical elements. One of the special things about the periodic table is how it is arraged, elements are listed in order of the increasing atomic number in rows. The atomic number is derived from the number of protons in the atoms nucleus. The columns in the periodic table are elements that are arranged with similar properties to other elements 
For example group 1 is Alkali metals. The Alkali metals are very reactive! This is because the 'outer ring' of each element has 1 electron and so this element will do anything to get rid of its electron making it very unstable. (Here's a quick video showing some of the elements reacting with water in a bath tub). They are so reactive that when cut with a knife they react with the atmosphere to form compounds (they are soft metals and so are easily cut with a knife). On the other hand group 8 or the 'Halogen Group' all have a full outer ring of electrons and so are very stable. An example of a Halogen is Neon (Ne), you may recognise this element as it is commonly used to create colourful lettering that light up - Neon Lights - it is used for this purpose and can be set-up outside shops without reacting and so will not cause harm to passers by.
The History
In 1869, a Russian chemist named Dmitri Mendeleev came up with a way of organizing the elements into a table - this was obviously the "Periodic Table" He set them out in order of the weight of the atom, and then grouped them into rows and columns based on their chemical and physical properties.
One of the things which made it even more incredible is that he was able to place these elements in the periodic table with out the aid of any modern equipment, but what I find quite amusing is that he played a sort of game to place these elements. What he did was he wrote the elements on a piece of card and played a sorting game with them ( their size, how much electrons each element had. etc) This then led to the shape of the periodic table.
The periodic table to left of Dmitri Mendeleev was his own version of the periodic table. As you can see from todays periodic table there are similarities but noticeable differences.
For example group 1 is Alkali metals. The Alkali metals are very reactive! This is because the 'outer ring' of each element has 1 electron and so this element will do anything to get rid of its electron making it very unstable. (Here's a quick video showing some of the elements reacting with water in a bath tub). They are so reactive that when cut with a knife they react with the atmosphere to form compounds (they are soft metals and so are easily cut with a knife). On the other hand group 8 or the 'Halogen Group' all have a full outer ring of electrons and so are very stable. An example of a Halogen is Neon (Ne), you may recognise this element as it is commonly used to create colourful lettering that light up - Neon Lights - it is used for this purpose and can be set-up outside shops without reacting and so will not cause harm to passers by.The History
In 1869, a Russian chemist named Dmitri Mendeleev came up with a way of organizing the elements into a table - this was obviously the "Periodic Table" He set them out in order of the weight of the atom, and then grouped them into rows and columns based on their chemical and physical properties.
One of the things which made it even more incredible is that he was able to place these elements in the periodic table with out the aid of any modern equipment, but what I find quite amusing is that he played a sort of game to place these elements. What he did was he wrote the elements on a piece of card and played a sorting game with them ( their size, how much electrons each element had. etc) This then led to the shape of the periodic table. The periodic table to left of Dmitri Mendeleev was his own version of the periodic table. As you can see from todays periodic table there are similarities but noticeable differences.
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